WO2005076592A1 - 所定領域内に形成されるドット個数の情報に基づいて画像を出力する画像出力システム - Google Patents
所定領域内に形成されるドット個数の情報に基づいて画像を出力する画像出力システム Download PDFInfo
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- WO2005076592A1 WO2005076592A1 PCT/JP2005/002527 JP2005002527W WO2005076592A1 WO 2005076592 A1 WO2005076592 A1 WO 2005076592A1 JP 2005002527 W JP2005002527 W JP 2005002527W WO 2005076592 A1 WO2005076592 A1 WO 2005076592A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/40—Picture signal circuits
- H04N1/405—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
- H04N1/4051—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a dispersed dots halftone pattern, the dots having substantially the same size
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/21—Ink jet for multi-colour printing
- B41J2/2121—Ink jet for multi-colour printing characterised by dot size, e.g. combinations of printed dots of different diameter
- B41J2/2128—Ink jet for multi-colour printing characterised by dot size, e.g. combinations of printed dots of different diameter by means of energy modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/41—Bandwidth or redundancy reduction
- H04N1/4105—Bandwidth or redundancy reduction for halftone screened pictures
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/41—Bandwidth or redundancy reduction
- H04N1/411—Bandwidth or redundancy reduction for the transmission or storage or reproduction of two-tone pictures, e.g. black and white pictures
- H04N1/413—Systems or arrangements allowing the picture to be reproduced without loss or modification of picture-information
- H04N1/415—Systems or arrangements allowing the picture to be reproduced without loss or modification of picture-information in which the picture-elements are subdivided or grouped into fixed one-dimensional or two-dimensional blocks
Definitions
- Image output system for outputting images
- the present invention relates to a technique for outputting an image based on image data, and more particularly, to a technique for outputting an image by performing predetermined image processing on image data and generating dots at an appropriate density.
- Image output devices that output images by forming dots on various output media such as print media and liquid crystal screens are widely used as output devices for various types of image equipment.
- images are handled in a state where they are subdivided into small areas called pixels. Dots (or even formed in these pixels. When dots are formed in pixels, it is of course possible to see each pixel) For example, it is only possible to determine whether a dot is formed or not, but if we look at a region with a certain size, it is possible to cause the density of the formed dot to vary. By changing the dot formation density, it is possible to output multi-tone images.
- An object of the present invention is to provide a simple image processing technology that can be executed without using a device having a high processing capability such as a personal computer.
- the present invention provides an image processing apparatus that performs predetermined image processing on image data, and an image output that outputs an image on an output medium by forming dots based on the result of the image processing.
- “number data” is transferred between the image processing device and the image output device.
- the “number of pieces of data” is data representing the number of dots to be formed for each pixel group in which a plurality of pixels constituting an image are grouped by a predetermined number.
- the invention of the present application handles the number data exchanged between the two devices. I. It has a common feature here and has the feature on the image processing device side (first mode), and outputs the feature to an image. This was realized as one with the device (second mode) and one with both devices (third mode). Hereinafter, these features will be briefly described. First, a first embodiment of the present invention will be described.
- the first image output system of the present invention employs the following configuration. That is,
- An image output system comprising: an image processing apparatus that performs predetermined image processing on image data; and an image output apparatus that outputs an image on an output medium by forming a dot based on a result of the image processing.
- the image processing device includes:
- Correspondence storage means for storing a correspondence between a combination of a classification number assigned to each pixel group and a pixel group gradation value of the pixel group, and number data representing the number of dots formed in the pixel group.
- a number data supply unit that generates a number data for each of the pixel groups and supplies the generated number data to the image output device by referring to the correspondence relationship;
- the image output device is the image output device
- Pixel position determining means for determining the pixel position
- a dot forming means for forming a dot on the output medium based on the determined pixel position
- the image output method of the present invention corresponding to the first image output system described above performs a predetermined image processing on image data, and forms a dot on an output medium based on the obtained result.
- a pixel group gradation value that is a gradation value representing the pixel group is determined based on image data of each pixel in the pixel group.
- a second relationship storing a combination of a combination of a classification number assigned to each pixel group and a pixel group gradation value of the pixel group, and a number data representing the number of dots formed in the pixel group.
- a fifth step of forming a dot on the output medium based on the determined pixel position is performed in the image output system and the image output method according to the present invention.
- an image is divided into a plurality of pixel groups, and number data representing the number of dots formed in the pixel groups is generated and supplied to the image output device.
- the order of the pixels at which dots are formed in the pixel group is stored in advance.
- the image output device determines a pixel position where a dot is formed in the pixel group based on the supplied number data and the order of the pixel, and outputs an image by forming a dot.
- the data representing the number of dots for each pixel group can be much smaller than the data representing the presence or absence of dot formation for all pixels of an image. For this reason, if the number data is supplied to the image output device, the data can be supplied quickly, and the image can be output quickly.
- the correspondence between the combination of the pixel group classification number and the pixel group gradation value and the number data is stored in advance, and the number data is referred to by referring to this correspondence. Generate.
- the process of generating the number data by referring to the correspondence is an extremely simple process.
- the pixel group tone value of the pixel group can be obtained very easily.
- the classification number can be determined very easily.
- the processing can be a very simple process. For this reason, it is possible to quickly generate the number data, and furthermore, it is possible to quickly supply the image data to the image output device and quickly output the image. Furthermore, if the number data can be generated by such an extremely simple process, it is possible to quickly generate the number data even in a device such as a computer that does not have a high processing capability. . Therefore, for example, the image data can be directly
- the image data it is also possible to supply the image data to the image output device, generate the number data inside the image output device, and output the image.
- a plurality of sets of pixel sequences are stored: When the number data is received, one pixel sequence is selected from each of the plurality of sequences to determine a pixel position. It may be. The pixel position in the pixel group is determined based on the pixel order and the number data. Therefore,
- the classification number of the pixel group may be given by classifying each pixel group into a plurality of types according to the position in the image. In this way, a classification number can be appropriately assigned as necessary without assigning a classification number to the pixel group in advance. Also, by assigning according to the position in the image, the classification number is assigned appropriately.
- a dither matrix in which a plurality of thresholds are two-dimensionally arranged is assumed, and a classification number set based on the dither matrix, the number data, and a pixel sequence are used to obtain an image. May be output.
- a description will be given focusing on a certain pixel group.
- a classification number of a pixel group is given based on the relative position of the pixel group with respect to the matrix when dither matrix is applied to the image.
- the number of dots formed in the pixel group is obtained by applying a dither method using dither matrix.
- the number data representing the number of dots thus obtained is stored in association with the combination of the classification number and the pixel group gradation value. Further, when the dither matrix is applied to the image, the order of the pixels in the pixel group is determined according to the magnitude of the threshold value set in the area corresponding to the pixel group,
- the obtained order is stored for each classification number.
- the classification number, the number of pixels, and the pixel order are set based on the same dither matrix, a dot is formed for each pixel using the dither method. It is possible to output an image with exactly the same image quality as when judging the presence or absence of the image.
- the image data of the pixels grouped as a pixel group has the same gradation value
- the presence or absence of dot formation is determined for each pixel using the dither method, and a dot is formed from the individual data.
- a dot is formed at exactly the same pixel position.
- the first image processing apparatus of the present invention has the following configuration. That is, An image processing apparatus that generates control data used by an image output device that forms a dot and outputs an image to control the formation of the dot by adding predetermined image processing to image data that represents the image And
- Pixel group tone value determining means For each pixel group in which a plurality of pixels constituting the image are grouped by a predetermined number, a pixel group gradation value that is a gradation value representing the pixel group is determined based on image data of each pixel in the pixel group. Pixel group tone value determining means,
- Correspondence storage storing a correspondence between a combination of a classification number assigned to each pixel group and a pixel group gradation value of the pixel group, and number data representing the number of dots formed in the pixel group.
- the present invention is characterized in that it comprises: a number data output unit that generates number data for each of the pixel groups by referring to the correspondence relationship and outputs the number data as the control data. Further, the first image processing method of the present invention corresponding to the first image processing apparatus is used in an image output apparatus for forming a dot and outputting an image reward for controlling the formation of the dot. An image processing method for generating control data by adding predetermined image processing to image data representing the image,
- a pixel group gradation value that is a gradation value representing the pixel group is determined based on image data of each pixel in the pixel group.
- the image is divided into a plurality of pixel groups by grouping a plurality of pixels constituting the image by a predetermined number and forming each pixel group.
- Number data representing the number of dots formed in the pixel group is generated, and the number data obtained for each pixel group is output as control data.
- the data representing the number of dots for each pixel group can be much smaller than the data representing the presence or absence of dot formation for all pixels of the image. By doing so, it becomes possible to output control data quickly.
- the correspondence between the combination of the pixel group classification number and the pixel group gradation value and the number data is stored in advance, and the number is determined by referring to the correspondence. Generating data.
- the process of generating the quantity data by referring to the correspondence is an extremely simple process, so that it is possible to output the control data quickly.
- the image processing apparatus of the present invention can be configured by incorporating it into a device that does not have a high processing capability, such as a convenience store. It is also possible to carry out the image processing method of the present invention using a device having no ability.
- the classification number of the pixel group may be given by classifying each pixel group into a plurality of types according to the position in the image. In this way, it is not necessary to assign a classification number to a pixel group in advance, and it is also possible to appropriately assign a classification number by assigning a classification number according to a position in an image.
- the number of pixels can be reduced without explicitly forming a pixel group by grouping a predetermined number of pixels.
- Data may be generated. That is, the image data is changed to a resolution such that the size of the pixel after conversion matches the size of the pixel group.
- one of the pixels whose resolution has been adjusted is treated as a pixel group to assign a classification number, and the gradation value of the image data for each pixel is treated as a pixel group gradation value.
- the number data of the pixel group is generated without explicitly grouping the plurality of pixels into the pixel group. Due to the demands on image quality, it is common to print images at a higher resolution than the resolution of the image data. In such a case, if the number data is generated by the above-described method, the image data can be converted to a resolution lower than the resolution to be printed, and the number data can be generated. In general, the higher the resolution, the larger the amount of data becomes, and the more difficult it becomes to handle.
- the number data representing the number of dots formed in the pixel group data representing a combination of the number of dots for a plurality of types of dots with different gradation values to be expressed is generated. You may do it.
- the plurality of types of dots expressing different gradation values may be, for example, a plurality of types of dots having different dot sizes, or a plurality of types of dots having different dot densities. You can also. Furthermore,
- pixels of four pixels in the main scanning direction and two or four pixels in the sub-scanning direction are grouped as a pixel group, and the pixel group gradation value is assigned to each pixel group. It may be determined. As a group of pixels ⁇ ) As the number of pixels decreases, the types of classification numbers increase, so the correspondence is complicated. Therefore, from this viewpoint, it is preferable that the number of pixels grouped into a pixel group is large. On the other hand, since the gradation values of the pixels included in the pixel group are combined into the pixel group gradation values, if the number of pixels combined in the pixel group is too large, the image quality may be deteriorated.
- the first image output device of the present invention has the following configuration. That is,.
- An image output device that outputs an image corresponding to the image data by forming a dot on an output medium according to the image data, For each pixel group in which a plurality of pixels constituting the image are grouped by a predetermined number, a pixel group gradation value that is a gradation value representing the pixel group is determined based on image data of each pixel in the pixel group. Pixel group tone value determining means,
- Correspondence storage storing a correspondence between a combination of a classification number assigned to each pixel group and a pixel group gradation value of the pixel group, and number data representing the number of dots formed in the pixel group.
- Number data generating means for generating number data for each of the pixel groups by referring to the correspondence relationship
- Pixel position determining means for determining a pixel position at which a pixel is formed
- Dot forming means for forming a dot on the output medium based on the determined pixel position.
- the image is divided into a plurality of pixel groups, and the number data representing the number of dots formed in the pixel group is generated.
- the pixel group tone value of the pixel group is obtained, and then generated by referring to the correspondence relationship between the combination of the pixel group classification number and the pixel group tone value and the count data. I do.
- a pixel position where a dot is to be formed in the pixel group is determined from the number data, and an image is output by forming a dot at the determined pixel.
- the pixel group gradation value of the pixel group can be obtained very easily. Therefore, if the correspondence between the combination of the pixel group classification number and the pixel group gradation value and the number data is determined in advance, and the number data is determined by referring to such correspondence, the number data can be extremely easily determined. Can be generated. For this reason, an image output device can be used without using a device having a high processing capability such as a combination device. Forming the number data in the device, determining the pixel position, and then forming the dots is preferable because the image can be output quickly. Further, the present invention can be realized using a computer by reading a program for implementing the above-described image output method or image processing method into a computer. Therefore, the present invention also includes the following program or a recording medium on which the program is recorded. That is, the first image output program of the present invention corresponding to the above-described first image output method includes:
- a computer-implemented program for performing predetermined image processing on image data and forming a dot on an output medium based on the obtained result to output an image using a computer
- a pixel group gradation value that is a gradation value representing the pixel group is determined based on image data of each pixel in the pixel group.
- a fourth function for determining the pixel position where the dot is formed is stored, and the dots are arranged in the pixel group based on the number data supplied for each pixel group and the order of the pixels.
- a first image processing program of the present invention corresponding to the above-described image processing method includes: A method of generating control data used by an image output device for forming a dot and outputting an image to control the formation of the dot by applying predetermined image processing to the image data representing the image, A program for realizing using a computer, wherein for each pixel group in which a plurality of pixels constituting the image are grouped by a predetermined number, a pixel group gradation value which is a gradation value representing the pixel group is displayed. (A) determining based on image data of each pixel in the pixel group;
- the step (C) of generating the number data for each of the pixel groups by referring to the correspondence and outputting the number data as the control data is realized. Further, it is of course possible to grasp the present invention as a recording medium on which the first image processing and image output program is recorded. If such a program or a program recorded on a recording medium is read at the convenience of a computer, and the various functions described above are realized using the computer, image processing and data transfer can be performed at high speed, and a simple Image processing can be realized. Next, a second embodiment of the present invention will be described.
- the second image output system of the present invention is:
- An image output system comprising: an image processing apparatus that performs predetermined image processing on image data; and an image output apparatus that outputs an image on an output medium by forming a dot based on a result of the image processing.
- the image processing apparatus includes:
- the image is divided into a group of pixels in which a plurality of pixels are grouped by a predetermined number, and number data representing the number of dots formed in each of the pixel groups is generated based on the image data.
- Means for generating quantity data
- Number data supply means for supplying the number data generated for each pixel group to the image output device
- the image output device is the image output device
- Order value obtaining means for obtaining, for each pixel in the pixel group, an order value indicating an order in which dots are formed in the pixel group;
- Correspondence storage means for storing a correspondence between a combination of the order value and the number data and the presence or absence of dot formation in a pixel having the order value
- the presence / absence of dot formation for each pixel in the pixel group is determined by referring to the correspondence for each combination of the number data and the respective order values.
- Means for determining whether or not to form a dot
- the gist is to provide Further, the second image output method of the present invention corresponding to the second image output system,
- the gist is to provide In the second image output system and image output method according to the present invention, an image is divided into a plurality of pixel groups, number data is generated for each pixel group, and supplied to the image output device.
- the image output device obtains an order value indicating the order in which dots are formed for each pixel in the pixel group: ⁇ .
- a continuous integer value starting from “1” may be set in advance for each pixel in the pixel group, and this integer value may be read and replaced with the order value.
- a real value of a different value may be set in advance for each pixel, and the order value of each pixel may be determined according to the order of the magnitude of the real value.
- a context may be set between the pixels, and the order value of each pixel may be determined based on the context.
- the image output device also stores the correspondence between the combination of the order value and the number data and the presence or absence of dot formation in pixels having the order value. Then, when the number data for the pixel group is received, the correspondence relationship is referred to based on a combination of the number data and the order value for each pixel in the pixel group, so that a dot for each pixel in the pixel group is obtained. Determine the presence or absence of formation. An image is output by forming dots on an output medium according to the presence or absence of dot formation determined in this way.
- the data representing the number of dots for each pixel group is far smaller than the data representing the presence or absence of dot formation for all the pixels of the image. Small data. For this reason, if the number data for each pixel group is supplied to the image output device, the data can be supplied promptly, and the image can be output quickly.
- the image output device receives the number data output for each pixel group, the image output device refers to the correspondence relationship based on a combination of the number data and the order value of each pixel in the pixel group, thereby obtaining the number of pixels in the pixel group. Is determined for each pixel.
- the presence or absence of dot formation for each pixel in the pixel group can be immediately determined from the number data, so that it is extremely quick and It can be easily determined, and the image can be output quickly. Furthermore, the presence / absence of dot formation can be determined by such an extremely simple process. Even if the image output device does not have a high processing capability like an image processing device, the number of dots can be reduced. It is possible to quickly determine the presence or absence of dot formation for each pixel from the evening. In such an image output system, the order value of each pixel may be obtained as follows to determine whether or not to form dots.
- a plurality of sets of the order of pixels in which dots are formed in the pixel group are stored, and one order is selected for each pixel group from the plurality of sets. Then, an order value for each pixel in the pixel group may be obtained based on the selected order, and the presence or absence of dot formation for each pixel may be determined based on the obtained order value. Whether or not a dot is formed for each pixel in the pixel group is determined based on the number data and the order value.
- the number data is generated based on a dither matrix that associates a threshold value with each of the two-dimensionally arranged pixels, and is acquired based on the same dither matrix.
- the order value may be used to determine whether or not dots are formed for each pixel. That is, the dither matrix is divided into a plurality of pixel groups, and the number of dots formed in the pixel group is obtained to generate number data.
- the divided dither matrix By using the divided dither matrix to determine the presence or absence of dot formation for each pixel in the pixel group, data of the number of dots formed in the pixel group may be generated. Alternatively, in order to generate the number data, since it is not necessary to know the pixel position where the dot is formed, the following can be simplified. First, only the threshold set for the divided dither matrix is stored for each pixel group. Next, a gradation value (representative gradation value) representing the pixel group is determined. As the representative gradation value, the average value of the image data of each pixel can be used, or since the image data has an approximate value between adjacent pixels, the pixel at a predetermined position in the pixel group Can be used as the representative gradation value.
- the number of threshold values smaller than the representative gradation value can be obtained for each pixel group, and the obtained value can be used as the number of dots of the pixel group.
- the presence or absence of dot formation for each pixel in the pixel group is determined as follows.
- the dither matrix used for generating the number data is divided into a plurality of pixel groups in advance, and a plurality of sets of the pixel order determined based on the threshold value associated with each pixel in the pixel group are stored. .
- the order value of each pixel is determined for each pixel group based on the magnitude relationship of the threshold value associated with each pixel in the pixel group, and a plurality of sets of the obtained order values are stored as the pixel order. Then, when the number data of the pixel group is received, the order of 1 corresponding to the position of the pixel group on the image is selected, and the order value of each pixel is obtained based on the order, and then the dot form is obtained. It is also possible to determine the presence or absence of the configuration. As will be described in detail later, in this way, the number of pixels in the pixel group is generated based on the dither matrix, and whether or not dots are formed for each pixel in the pixel group is determined in the same dither matrix.
- the second image output device of the present invention has the following configuration. That is,
- An image output device that receives an image data on which predetermined image processing has been performed, and forms a dot on an output medium based on the image data, thereby outputting an image
- Number data representing the number of dots to be formed in the pixel group in a state where a plurality of pixels constituting the image are grouped into a predetermined number of pixels to divide the image.
- an order value obtaining means for obtaining an order value indicating an order in which dots are formed in the pixel group
- a correspondence relationship storage unit that stores a correspondence relationship between a combination of the order value and the number data, and whether or not dots are formed in pixels having the order value
- a dot formation presence / absence determining means for determining the presence / absence of dot formation by referring to the correspondence for each combination of the number data and the order value for each pixel in the pixel group receiving the number data;
- the gist is to provide A second image output method of the present invention corresponding to the second image output device described above receives image data on which predetermined image processing has been performed, and forms a dot on an output medium based on the image data.
- Step (A) In a state in which a plurality of pixels constituting the image are grouped into a pixel group by a predetermined number in order to divide the image, the number data representing the number of dots to be formed in the pixel group is received as the image data.
- Determining the presence or absence of dot formation by referring to the correspondence for each combination of the number data and the order value for each pixel in the pixel group that has received the number data; (E) forming a dot on the output medium in accordance with the determined presence or absence of the dot formation;
- the gist is to provide In the second image output apparatus and the second image output method, when the number data of the pixel group is received, the combination of the order value and the number data and the presence / absence of dot formation in the pixel having the order value are determined. The presence or absence of dot formation is determined for each pixel in the pixel group while referring to the correspondence. An image is output by forming dots on the output medium in accordance with the presence or absence of dot formation determined in this way. As will be described later, if the number data of the pixel group can be received quickly, the image can be output quickly.
- the presence or absence of the dot formation of 1: for each pixel can be determined by referring to the correspondence set for each combination of the number data and the order value, so that the determination can be made easily and quickly. it can. For this reason, it is possible to output an image quickly, and to output an image at a sufficiently practical speed even in an image output device that does not have a high processing capability.
- the second image output device a plurality of sets of pixels in which dots are formed in a pixel group are stored, and the order value of each pixel is stored for each of the pixels.
- one order is selected for each pixel group from the plurality of orders, and the presence or absence of dot formation for each pixel is determined using the order value obtained based on the order. It may be.
- the same is applied to a plurality of pixel groups. Since no dot is formed at the pixel position, it is possible to avoid that the area where the dot is formed in the same pattern becomes conspicuous and the image quality is deteriorated.
- a plurality of types of dots having different gradation values to be expressed can be output, and the number of various types of dots formed in the pixel group may be received as number data.
- the plurality of types of dots having different gradation values may be, for example, a plurality of types of dots having different dot sizes, or a plurality of types of dots having different dot densities. It can also be. Furthermore, when one dot is formed in a pseudo manner by forming fine dots at a predetermined density, it is possible to use a plurality of types of dots having different densities of fine dots. It is. When these various dots can be formed, a combination of the number of various dots is received as number data. Then, the correspondence between the combination of the order value and the number data and the type of dot formed in the pixel having the order value is stored, and when the count data is received, the correspondence is referred to.
- the type of dot formed in each pixel may be determined, and various dots may be formed on the output medium according to the determined presence / absence of dot formation. If the presence or absence of dot formation for each pixel in the pixel group is determined with reference to the correspondence, even if the number data is data indicating a combination of the number of dots for multiple types of dots, each pixel The presence or absence of dot formation for can be determined very easily, as in the case of data simply representing the number of dots. For this reason, it is preferable because the presence or absence of the dot formation can be quickly determined and the image can be quickly output. In such an image output device, it is necessary to receive the number data for a pixel group in which eight to sixteen pixels each having a predetermined positional relationship are put together.
- the number of pixels grouped as a pixel group increases, the number of pixel groups decreases, so that the number data can be received quickly.
- the number of pixels to be collected in the pixel group is too large, the image quality may be deteriorated.
- experience has shown that the best results can be obtained when 8 to 6 pixels are combined into a pixel group. That is, as will be described in detail later, if the number of pixels to be grouped into a pixel group is changed from 8 pixels to 16 pixels, the data amount of the number data is reduced to half of the data indicating the presence or absence of dot formation for each pixel. It can be reduced to the following, and data can be received quickly.
- the positional relationship of a plurality of pixels grouped into a pixel group may be, for example, a positional relationship such that each pixel forms a rectangular shape, such as four pixels in the main scanning direction and two pixels in the sub-scanning direction.
- the image processing output device of the present invention has the following configuration. That is,
- An image processing output device that outputs an image corresponding to the image data by forming a dot on an output medium in accordance with the image data
- the image is divided into a set of pixel groups in which a plurality of pixels are grouped by a predetermined number, and the number data representing the number of dots formed in each of the pixel groups is generated based on the image data.
- Data generation means
- an order value obtaining means for obtaining an order value indicating an order in which dots are formed in the pixel group
- a correspondence relationship storage unit that stores a correspondence relationship between a combination of the order value and the number data, and whether or not dots are formed in pixels having the order value
- the presence or absence of dot formation is determined by referring to the correspondence for each combination of the number data and the order value. Means for determining whether a dot is to be formed,
- the gist is to provide In the image processing output device of the present invention as well, the image is divided into a plurality of pixel groups, and number data representing the number of dots formed in the pixel groups is generated. Next, the presence or absence of the dot formation for each pixel in the pixel group is determined with reference to the correspondence between the combination of the order value and the number data and the presence or absence of the dot formation in the pixel having the order value. An image is output by forming dots on an output medium according to the presence / absence of dot formation determined in this way. If the presence or absence of dot formation for each pixel is determined with reference to the correspondence set for each combination of the number data and the order value in this way, it is possible to determine easily and quickly.
- the present invention can be realized by using a computer to read a program for implementing the above-described image output method or image processing output method into a computer. Therefore, the present invention includes an embodiment as a program or a recording medium on which the program is recorded. If such a program or a program recorded on a recording medium is read at the convenience of a computer and the various functions described above are realized using the computer, it is possible to easily and quickly output an image.
- a third embodiment of the present invention will be described. In the third embodiment, the image in the first embodiment
- the third image output system of the present invention employs the following configuration. That is, an image output system including an image processing apparatus that performs predetermined image processing on image data and an image output apparatus that outputs an image on an output medium by forming a dot based on the result of the image processing. So,
- the image processing device includes:
- Pixel group tone value determining means for determining For each pixel group in which a plurality of pixels constituting the image are grouped by a predetermined number, a pixel group gradation value that is a gradation value representing the pixel group is calculated based on image data of each pixel in the pixel group.
- a first correspondence which is a correspondence between a combination of a classification number assigned to each pixel group and a pixel group gradation value of the pixel group, and number data representing the number of dots formed in the pixel group is referred to.
- a number data supply unit that generates a number data for each of the pixel groups and supplies the generated number data to the image output device;
- the image output device is the image output device
- An order value storage unit that stores, for each pixel in the pixel group, an order value indicating an order in which dots are formed in the pixel group;
- a second correspondence relationship which is a correspondence relationship between the combination of the order value and the number data and the presence / absence of dot formation in the pixel having the order value
- the pixel group receiving the number data is referred to.
- a pixel group gradation value that is a gradation value representing the pixel group is determined based on image data of each pixel in the pixel group.
- each of the pixels in the pixel group that generated the number data is referred to.
- the gist is that it is provided.
- the image is divided into a plurality of pixel groups, and a number data representing the number of dots formed in the pixel groups is generated.
- the image output device supplies the supplied number data.
- the data representing the number of dots for each pixel group can be much smaller than the data representing the presence or absence of dot formation for all pixels of an image.
- the number data is supplied to the image output device, the data can be supplied quickly, and the image can be output quickly.
- the number data is generated by referring to the correspondence (first correspondence) between the combination of the pixel group classification number and the pixel group gradation value and the number data.
- the process of generating quantity data by referring to the correspondence is a very simple process.
- the pixel group gradation value of the pixel group can be obtained very easily.
- the classification number can be determined very easily, so that the process of generating the quantity data can be a very simple process.
- the image output device determines whether or not to form dots for each pixel in the pixel group as follows. First, an order value indicating the order in which dots are formed in the pixel group is stored in advance for each pixel in the pixel group. Then, by referring to the correspondence (second correspondence) between the combination of the order value and the count data and the presence / absence of dot formation at the pixel having the order value, the pixel group to which the count data is supplied is referred to. For each pixel inside, determine whether or not to form dots.
- the dot for each pixel in the pixel group can be determined. Since the presence / absence of formation can be determined immediately from the number data, it is possible to determine very quickly and easily, and furthermore, it is possible to output an image quickly. Furthermore, if the process of generating the number data and the process of determining the presence or absence of dot formation for each pixel in the pixel group from the number data can be executed by such a very simple process,
- the classification number of the pixel group may be given by classifying each pixel group into a plurality of types according to the position in the image. In this way, a classification number can be appropriately assigned as needed without assigning a classification number to a pixel group in advance. Also, by assigning according to the position in the image, the classification number can be assigned appropriately. From such a viewpoint, the present invention can be understood as the following image output device. That is, the third image output apparatus of the present invention corresponding to the third image output system or the third image output method described above,
- An image output device that outputs an image corresponding to the image data by forming a dot on an output medium in accordance with the image data
- Pixel group tone value determining means For each pixel group in which a plurality of pixels constituting the image are grouped by a predetermined number, a pixel group gradation value that is a gradation value representing the pixel group is determined based on image data of each pixel in the pixel group.
- Pixel group tone value determining means A first correspondence, which is a correspondence between a combination of a classification number assigned to each pixel group and a pixel group gradation value of the pixel group, and number data representing the number of dots formed in the pixel group is referred to.
- a number data generating means for generating number data for each of the pixel groups;
- An order value storage unit that stores, for each pixel in the pixel group, an order value indicating an order in which dots are formed in the pixel group;
- each of the pixels in the pixel group that generated the number data is referred to.
- the gist is to provide In the third image output device, the image is divided into a plurality of pixel groups, and the number data is generated for each pixel group by referring to the first correspondence. Next, by referring to the second correspondence, the presence or absence of dot formation for each pixel in the pixel group is determined from the number data. An image is output by forming dots on the output medium based on the result determined in this way. Thus, if the image data is converted while referring to these correspondences, it is possible to output the image easily and quickly. Furthermore, it is possible to configure an image output device capable of outputting an image at a sufficiently practical speed even in a device such as a computer that does not have a high processing capability.
- the present invention in the third aspect can be understood as an image processing control system that performs up to generation of dots to be formed. That is, A first image processing apparatus for performing predetermined image processing on image data, and control data used for controlling the formation of dots when forming dots on an output medium and outputting an image.
- An image processing control system comprising: a second image processing device that generates based on a result of the image processing.
- the first image processing device includes:
- Pixel group tone value determining means for determining For each pixel group in which a plurality of pixels constituting the image are grouped by a predetermined number, a pixel group gradation value that is a gradation value representing the pixel group is calculated based on image data of each pixel in the pixel group.
- a first correspondence relationship which is a correspondence relationship between a combination of a classification number assigned to each pixel group and a pixel group gradation value of the pixel group, and number data representing the number of dots formed in the pixel group.
- the second image processing device includes:
- Order value storage means for storing, for each element in the pixel group, an order value indicating the order in which dots are formed in the pixel group;
- Control data generating means for generating the control data by determining whether or not dots are formed for each pixel in the
- the image processing control method of the present invention corresponding to the above-described image processing control system includes a control data used for controlling the formation of the dot when forming the dot and outputting the image.
- An image processing control method generated by applying predetermined image processing to image data representing an image, For each pixel group in which a plurality of pixels constituting the image are grouped by a predetermined number, a pixel group gradation value that is a gradation value representing the pixel group is determined based on image data of each pixel in the pixel group. (A)
- a first correspondence relationship which is a correspondence relationship between a combination of a classification number assigned to each pixel group and a pixel group gradation value of the pixel group, and number data representing the number of dots formed in the pixel group, is referred to.
- a second correspondence relationship which is a correspondence relationship between the combination of the order value and the number data and the presence / absence of dot formation in a pixel having the order value
- the number data in the pixel group that generated the number data is referred to.
- the gist is to provide
- the image is divided into a plurality of pixel groups by forming a pixel group by grouping a plurality of pixels constituting the image by a predetermined number. Generates the number data representing the number of dots formed inside.
- control data is generated by determining the presence or absence of dot formation for each pixel in the pixel group based on the number data generated for each pixel group. As will be described later, data representing the number of dots for each pixel group is smaller than data representing the presence / absence of dot formation for all pixels of the image. Control data can be generated easily and quickly.
- the number data When generating the number data, the number data is generated by referring to the first correspondence, that is, the correspondence between the combination of the pixel group classification number and the pixel group gradation value and the number data. Therefore, the number data can be generated quickly and with extremely simple processing. Furthermore, when generating the control data from the number data, the second correspondence, that is, the correspondence between the combination of the order value and the number data and the presence / absence of dot formation in the pixels having the order value is also considered. Because it is generated by reference, it is quick and extremely simple processing,
- Control data can be generated from the number data. As a result, control data can be easily and quickly generated from the image data, and further, by using the generated control data, an image can be output quickly. Furthermore, since control data can be generated from image data by extremely simple processing, control data can be generated at a sufficiently practical speed even for devices that do not have high processing capabilities such as computers. It is possible.
- the present invention can be understood as the following image processing control device. That is, the image processing control system of the present invention corresponding to the image processing control system or the image processing control method described above includes:
- An image output device that forms a dot and outputs an image generates control data used to control the formation of the dot by performing predetermined image processing on the image data representing the image.
- Pixel group tone value determining means For each pixel group in which a plurality of pixels constituting the image are grouped by a predetermined number, a pixel group gradation value that is a gradation value representing the pixel group is determined based on image data of each pixel in the pixel group. Pixel group tone value determining means,
- a first correspondence which is a correspondence relationship between a combination of a classification number assigned to each pixel group and a pixel group gradation value of the pixel group, and number data representing the number of dots formed in the pixel group
- a number data supply unit for generating number data for each of the pixel groups by referring to the relationship
- Order value storage means for storing, for each pixel in the pixel group, an order value indicating an order in which dots are formed in the pixel group;
- the gist is to provide In such an image processing control device, after an image is divided into a plurality of pixel groups, number data is generated for each pixel group from the image data by referring to the first correspondence relationship, and then the second correspondence relationship is generated. By reference, control data is generated from the number data for each pixel group. As described above, by performing conversion while referring to these correspondences, it is possible to easily and quickly generate control data. Furthermore, it is possible to configure an image processing apparatus that can generate control data at a sufficiently practical speed even for a device that does not have a high processing capability, such as a convenience store. In such an image processing control system, image processing control method, or image processing control device, the following may be performed.
- a plurality of sets of the order of the pixels in which the dots are formed in the pixel group are stored, and the order value of each pixel in the pixel group is stored for each order of each pixel.
- an order of 1 is selected for each pixel group from the plurality of sets, and the presence or absence of dot formation for each pixel in the pixel group is determined using the order value stored in the selected order.
- This generates control data.
- the presence or absence of dot formation for each pixel in the pixel group is determined by the number data of the pixel group. It is determined based on the order value of each pixel in the pixel group.
- the order value of each pixel is different for each pixel group. Therefore, even when the same number data continues over a plurality of pixel groups, dots are not formed at the same pixel positions in these pixel groups because the order values are different. For this reason, it is possible to reliably avoid the region where the dots are formed in the same pattern from being conspicuous and the image quality deteriorating.
- the classification number of the pixel group can be assigned in the same manner as in the first embodiment of the present invention.
- a dither matrix in which a plurality of thresholds are two-dimensionally arranged is assumed, and a classification number set based on the dither matrix is set.
- the control data may be generated using the data, the count data, and the order value.
- description will be made focusing on a certain pixel group.
- a pixel group classification number is assigned based on the relative position of the pixel group with respect to the matrix when dither matrix is applied to the image.
- the number of dots formed in the pixel group is obtained by applying a dither method using a dither matrix.
- the number data representing the number of dots thus obtained is stored as a first correspondence in association with the combination of the classification number and the pixel group gradation value. Further, when the dither matrix is applied to the image, the order value for each pixel in the pixel group is determined according to the threshold value set in the region corresponding to the pixel group, and the obtained order value is obtained. Are stored as the order of a plurality of sets of pixels. Then, when the number data of the pixel group is generated, the order of 1 corresponding to the position of the pixel group is selected on the image, and the order value set in the order is used to select each pixel. Control data is generated by judging the presence or absence of all dot formation.
- the presence or absence of dot formation for each pixel using the dither method It is possible to output an image with exactly the same image quality as that in the case of judging.
- the image data of the pixels grouped as a pixel group has the same gradation value
- the presence or absence of dot formation for each pixel is determined by using the dither method, and the number data is used for each pixel.
- the presence or absence of dot formation is determined, a dot is formed at exactly the same pixel position.
- the classification number, the number data, and the order value may be set based on a dither matrix having a so-called blue noise mask characteristic.
- the “dither matrix having the blue noise mask characteristic” in this specification refers to the following matrix.
- the dots are generated irregularly, and the spatial frequency component of the set threshold value is the dither matrix having the largest component in the high frequency region where one cycle is 2 pixels or less.
- dots may be formed in a regular pattern near a specific brightness, such as a bright (high brightness) image. If the classification number, quantity data, and ordinal value are set based on such a dither matrix having a blue noise mask characteristic, an image can be output with a dot distribution reflecting the blue noise mask characteristic.
- the classification number, the number data, and the order value may be set based on a dither matrix having so-called green noise mask characteristics.
- the “dither matrix having a green noise mask characteristic” in this specification refers to the following matrix.
- the dots are generated irregularly, and the set spatial frequency component of the threshold is a dither matrix having the largest component in an intermediate frequency region in which one cycle is from two pixels to more than ten pixels.
- a dot may be formed in a regular pattern near a specific brightness.
- image output equipment such as the so-called laser printer
- the use of dither matrices having such a green noise mask characteristic allows the isolated Dot generation can be suppressed. As a result, images with stable image quality can be output quickly. Note that such a method can be adopted in the first and second aspects of the present invention. Of course.
- a predetermined number of pixels are explicitly collected by adjusting the resolution of image data to the following resolution.
- the number data may be generated without forming a pixel group. That is, the image data is changed to a resolution such that the size of the pixel after conversion matches the size of the pixel group.
- a classification number is assigned by treating each of the pixels whose resolution has been adjusted as a pixel group, and the gradation value of the image data for each pixel is treated as a pixel group gradation value. Generate count data for each pixel.
- the number data of the pixel group is generated without explicitly grouping the plurality of pixels into the pixel group.
- the image data can be converted to a resolution lower than the resolution to be printed, and the number data can be generated.
- the higher the resolution the greater the data volume and the more difficult it becomes to handle the image data.
- Generating the number data at a lower resolution generally facilitates the handling of the data. Even the process of generating evening can be speeded up.
- image processing control method, or image processing control device as the number data representing the number of dots formed in the pixel group, a plurality of types of dots having different gradation values are expressed.
- the plurality of types of dots expressing different gradation values may be, for example, a plurality of types of dots having different dot sizes, or a plurality of types of dots having different dot densities. You You can also. Furthermore, by forming fine dots at a predetermined density,
- a plurality of types of dots having different densities of fine dots can be used.
- the number data for each pixel group can be calculated. Generate. Then, by referring to a second correspondence relationship indicating a correspondence relationship between the combination of the order value and the number data and the dot type formed in the pixel having the order value, the number generated for each pixel group is obtained. Control data is generated by determining whether or not various dots are formed for each pixel from the data.
- the number data is data indicating a combination of the number of dots for a plurality of types of dots, but simply data representing the number of dots As in the case of, the number data can be generated very easily.
- S always, when judging the presence or absence of dot formation for each pixel, as the number of types of dots increases, the process of making judgments becomes more complicated, and it tends to be complicated, so refer to the first correspondence.
- By generating the number data it is preferable to increase the number of types of the dots because the number can be relatively quickly generated.
- the process of determining the presence or absence of dot formation for each pixel tends to be complicated as the number of types of dots increases, but the presence or absence of formation of various dots is determined by referring to the second correspondence. Once determined, it can be easily determined even if there are many types of dots. That is, it is possible to relatively quickly determine whether or not to form dots. After all, the larger the number of types of dots, the faster the control data can be generated from the image data, which is preferable. Further, the above-described image processing control system, image processing control method, or image processing In the control device, four to sixteen pixels having a predetermined positional relationship with each other may be grouped as a pixel group to determine a pixel group gradation value.
- the number of pixel groups increases as the number of pixels grouped as a pixel group decreases, the first correspondence becomes complicated. Therefore, from this viewpoint, it is preferable that the number of pixels grouped into a pixel group is large.
- the gradation values of the pixels included in the pixel group are combined into the pixel group gradation values, if the number of pixels combined in the pixel group is too large, the image quality may be deteriorated. Based on these points, the best experience can be obtained from a case where 8 to 16 pixels are grouped together into a pixel group, but 4 to 16 pixels are collected. Sufficient results can be obtained even when grouped.
- the positional relationship of a plurality of pixels combined into a pixel group may be, for example, a positional relationship that forms a rectangular shape with respect to each other, such as four pixels in the main scanning direction and two pixels in the sub-scanning direction. From experience, it is possible to obtain good image quality.
- the present invention can be realized by using a computer to read a program for implementing the above-described image output method or image processing control method. Therefore, the present invention also includes the following program or an embodiment as a recording medium on which the program is recorded.
- FIG. 1 is an explanatory diagram illustrating a first embodiment of the present invention using a printing system as an example.
- FIG. 2 is an explanatory diagram illustrating a configuration of a computer as an image processing apparatus according to the present embodiment.
- FIG. 3 is an explanatory diagram illustrating a schematic configuration of a color printer according to the present embodiment.
- FIG. 4 is an explanatory diagram showing an arrangement of inkjet nozzles in the ink ejection head.
- FIG. 5 is a flowchart showing the overall flow of the image printing process of the first embodiment.
- FIG. 6 is an explanatory diagram conceptually illustrating a part of the dither matrix.
- FIG. 7 is an explanatory diagram conceptually showing a state in which the presence or absence of dot formation is determined for each pixel with reference to the dither matrix.
- FIGS. 8A to 8D are explanatory diagrams showing a state in which image data is converted into data representing the presence or absence of dot formation using the dither method.
- FIGS. 9A to 9D are explanatory diagrams showing how to generate data indicating the presence or absence of dot formation for each pixel from the data of the number of dots.
- FIG. 10 is a flowchart illustrating the flow of the count data generation process according to the first embodiment.
- FIG. 11a to FIG. 11c are explanatory diagrams showing a concept for determining a classification number for each pixel group. .
- FIGS. 12a to 12d are explanatory diagrams showing a method of determining the classification number of the pixel group.
- FIG. 13 is an explanatory diagram showing a specific method for determining a classification number of a pixel group.
- FIG. 14 is an explanatory diagram conceptually showing a conversion table referred to for obtaining the number data from the pixel group classification number and the pixel group gradation value.
- FIG. 15 is an explanatory diagram conceptually showing how appropriate number data is determined according to the combination of the pixel group classification number and the pixel group gradation value.
- FIG. 16 is a flowchart illustrating the flow of the pixel position determination process according to the first embodiment.
- FIG. 17 is an explanatory diagram showing the results of trial calculation of the data size of the conversion table under various conditions.
- FIG. 18 is a flowchart showing the flow of an image printing process according to a modification of the first embodiment.
- FIGS. 19a to 19c are explanatory diagrams showing the processing performed in the resolution adjustment processing.
- FIG. 20 is a flowchart showing the flow of the number data generation process performed in the image printing process of the modified example.
- FIG. 21 is a flowchart showing the flow of processing for determining the number of large, medium, and small dots formed in a pixel group using a so-called dither method.
- FIG. 22 is a flowchart showing the flow of processing for determining whether or not each of large, medium, and small dots is formed by performing halftone processing on a selected pixel.
- FIG. 23 is an explanatory view conceptually showing a dot density conversion table referred to when converting the gradation value of image data into density data for each of large, medium and small dots.
- FIG. 24 is an explanatory diagram conceptually showing a state in which the presence or absence of large, medium and small dots is determined while applying the dither method to each pixel in the pixel group.
- FIG. 25 is an explanatory diagram conceptually showing a state in which the number of large, medium, and small dots formed in the pixel group is obtained.
- FIG. 26 is an explanatory diagram showing a correspondence table in which combinations of the numbers of large, medium, and small dots formed in a pixel group are associated with coded number data.
- FIG. 27 is a flowchart illustrating the flow of the count data generation process according to the second embodiment.
- FIG. 28 is an explanatory diagram conceptually showing a conversion table referred to in the count data generation processing of the second embodiment.
- FIG. 29 is a flowchart illustrating the flow of the pixel position determination process according to the second embodiment.
- FIG. 30 is an explanatory diagram conceptually showing a decoding table referred to for decoding the number data coded in the pixel position determination processing of the second embodiment.
- FIG. 31 is an explanatory diagram conceptually showing how pixel positions for forming large, medium, and small dots are determined with reference to an order matrix.
- FIG. 32 is an explanatory view conceptually showing another mode of the decoding table referred to for decoding the encoded number data.
- FIG. 33 is an explanatory diagram showing the results of trial calculation of the data size of the conversion table under various conditions in the second embodiment.
- FIG. 34 is an explanatory diagram for describing the second embodiment of the present invention using a printing system as an example.
- FIG. 35 is a flowchart illustrating the overall flow of the image printing process according to the third embodiment.
- FIG. 36 is a flowchart illustrating the flow of the count data generation process according to the third embodiment.
- FIG. 37 is a flowchart showing the flow of the dot on-off state determination process of the third embodiment.
- FIGS. 38a to 38c are explanatory diagrams conceptually showing a state in which the presence / absence of dot formation is determined for each pixel in the dot formation presence / absence determination processing of the third embodiment.
- FIG. 39 is an explanatory diagram conceptually showing a conversion template referred to for determining whether or not a dot is formed for a target pixel.
- FIG. 40 is a flowchart showing the flow of a dot formation presence / absence determination process according to a modification.
- FIGS. 41a to 41d are explanatory diagrams showing a method of generating a plurality of order value matrices referred to in the dot formation presence / absence determination processing of the modified example.
- FIGS. 42a to 42d are explanatory diagrams showing a method of selecting an order value matrix corresponding to a pixel group.
- FIG. 7 is an explanatory diagram specifically showing a method of selecting.
- FIG. 44 is an explanatory diagram showing the results of trial calculation of the amount of memory required to store the order value matrix, assuming a dither matrix of various sizes and a pixel group of various sizes.
- FIG. 45 is a flowchart showing the flow of a process for determining the number of various large, medium, and small dots formed in the pixel group and generating the number data.
- FIG. 46 is a flowchart showing the flow of processing for determining whether or not various large, medium, and small dots are formed without referring to the conversion table.
- FIG. 47 is an explanatory diagram conceptually showing a conversion table referred to in the dot formation presence / absence determination processing of the fourth embodiment.
- FIG. 48 is an explanatory diagram summarizing the results of trial calculation of the amount of memory required to store the conversion table for each pixel group size.
- FIG. 49 is an explanatory diagram for describing the third embodiment of the present invention using a printing system as an example.
- FIG. 50 is a flowchart showing the flow of the count data generation process of the fifth example).
- FIG. 51 is a flowchart showing the flow of the dot formation presence / absence determination processing of the fifth embodiment.
- FIG. 52 is an explanatory diagram conceptually illustrating a dither matrix having a blue noise mask characteristic and a spatial frequency characteristic of a threshold set in the dither matrix having a green noise mask characteristic.
- FIG. 1 is an explanatory diagram illustrating a first embodiment of the present invention using a printing system as an example.
- the printing system includes a computer 10 as an image processing device, a printer 20 as an image output device, and the like.
- a predetermined program is loaded into the computer 10 and executed, the computer 10 10 and pudding 20 as a whole function as an integrated image output system.
- the printer 20 prints an image by forming dots on a print medium.
- the computer 10 performs predetermined image processing on the image data of the image to be printed, so that the printer 20 generates data for controlling the formation of dots for each pixel. Supply.
- a typical printing system prints an image as follows.
- image data is converted into data representing the presence or absence of dot formation on a pixel-by-pixel basis by performing predetermined image processing at a short time. Then, the obtained data is supplied to a printer, and the printer prints an image by forming a dot according to the supplied data.
- the printing system illustrated in Fig. 1 prints an image as follows.
- the computer 10 divides an image into a plurality of pixel groups by grouping pixels constituting an image into a predetermined number of adjacent pixels. Then, for each pixel group, number data representing the number of dots formed in the pixel group is generated and supplied to the printer 20.
- the printer 20 When the printer 20 receives the number data for each pixel group, it determines the pixel position for forming a dot for each pixel group with reference to the order storage module.
- the order storage module stores the order of pixels in each of which a dot is formed in a pixel group.
- the pixel position determination module determines a pixel position where a dot is to be formed, based on the order of the pixels and the number data of the pixel group.
- the image is printed by the dot forming module forming dots at the pixel positions determined in this way.
- the number data for each pixel group can be a much smaller data amount.
- the number data of the pixel group is generated in the computer 10 as follows. First, in a pixel group tone value determination module, pixel group tone values are determined for a plurality of pixel groups that divide an image. Pixel group gradation value is the gradation that represents the pixel group And is determined based on the image data of each pixel included in the pixel group. Also, the correspondence storage module contains
- the correspondence between the combination of the classification number assigned to the pixel group and the pixel group gradation value and the number data of the pixel group having the combination is stored.
- the classification number of the pixel group can be set by classifying each pixel group into a plurality of types according to the position in the image, or when the image is always divided in the same manner.
- An appropriate classification number can be assigned in advance to each pixel group.
- the counting data overnight supply module refers to the correspondence between the classification number and the pixel group gradation value and the number data to obtain the classification number and the pixel group gradation value of each pixel group.
- the number data is determined for each pixel group based on the pixel data, it is supplied to the printer 20.
- the pixel group gradation value of the pixel group can be easily obtained.
- the classification number of each pixel group can be easily determined and assigned.
- the number data can be easily obtained from the classification number and the pixel group gradation value.
- the printing system illustrated in FIG. 1 can generate the number data for each pixel group very quickly, and can supply the generated number data to the printer 20 very quickly. Therefore, even if the image has a large number of pixels, the image can be printed quickly.
- FIG. 2 is an explanatory diagram illustrating a configuration of a computer 100 as an image processing apparatus according to the present embodiment.
- the computer 100 is a well-known computer configured by connecting a ROM 104, an RA 106, and the like to each other via a bus 116, centering on a CPU 102.
- the computer 100 has a disk controller DDC 109 for reading data such as a flexible disk 124 and a compact disk ⁇ 26, and a peripheral device interface PIF 100 for exchanging data with peripheral devices.
- the video interface VIF 112 for driving the CRT 114 is connected.
- the PIF 108 is connected to a color printer 200 described later, a hard disk 118, and the like.
- FIG. 3 is an explanatory diagram illustrating a schematic configuration of the color printer 200 of the present embodiment.
- the color printer 200 is an inkjet printer that can form dots of four color inks of cyan, magenta, yellow, and black.
- a total of six ink dots including cyan (light cyan) ink with a low dye or pigment concentration and magenta (light magenta) ink with a low dye or pigment concentration, are used.
- a formable inkjet printer can also be used.
- the light cyan ink and the light magenta ink may be abbreviated as C ink, M ink, Y ink, K ink, LC ink, and LM ink, respectively.
- the color printer 200 has a mechanism for driving a print head 241, which is mounted on a carriage 240, to discharge ink and form dots.
- the carriage 240 is equipped with an ink cartridge 242 for storing K ink, and an ink cartridge 243 for storing various inks of C ink, M ink and ⁇ ink.
- each ink in the cartridge is discharged through an introduction pipe (not shown) to discharge ink for each color provided on the lower surface of the print head 241. Supplied to heads 2 4 4 to 2 4 7.
- the control circuit 260 includes a CPU, a ROM, a RAM, a PIF (peripheral device interface), and the like, which are interconnected by a bus. The control circuit 260 controls the operation of the carriage mode 230 and the paper feed mode 230 by controlling the operation of the carriage mode.
- the main scanning operation and the sub-scanning operation of the cartridge 240 are controlled, and the control of ejecting ink droplets from each nozzle at an appropriate timing is performed based on the print data supplied from the computer 100.
- the color printer 200 can print a color image by forming ink dots of each color at appropriate positions on the print medium under the control of the control circuit 260. Also, by controlling the drive signal waveform supplied to the nozzles to eject ink droplets,
- the color printer 200 having the hardware configuration as described above drives the carriage motor 230 so that the ink discharge heads 24 4 to 24 7 of each color are printed on the printing paper P.
- the printing paper P is moved in the sub-scanning direction by moving it in the main scanning direction and driving the paper feed module 235.
- the control circuit 260 synchronizes with the main scanning and sub-scanning movements of the carriage 240,
- the color printer 200 prints a color image on printing paper by driving the nozzles to discharge ink droplets at the timing.
- the color printer 200 also has a CPU, RAM, ROM, etc. in the control circuit 260, the processing performed by the computer 100 is performed in the color printer 200. It is also possible. In such a case, the image data of the image captured by the digital camera 120 or the like is directly supplied to the color printer 200, and the necessary image processing is performed in the control circuit 260, so that the color data can be obtained. It is also possible to print an image directly from the printer 200.
- the first half of the image printing process is performed by the computer 100, and the second half is performed by the color printer 200. It can be implemented inside the printer 200 or inside a device that generates image data, such as a digital camera 120. That is, according to the image printing process of the present embodiment, as will be described in detail later, the first half of the process can be made very simple, so that a CPU that does not have high processing capability is used. But it can be done quickly. Therefore, even when the first half of the image printing process is incorporated in the color printer 200, digital camera, or the like, a sufficiently practical printing system can be configured.
- step S100 the computer # 100 starts reading image data
- the image data is RGB color image data
- the present invention is not limited to color image data, but can be similarly applied to monochrome image data.
- the present invention can be similarly applied to a monochrome printer as well as a color printer.
- a color conversion process is performed (step S102).
- Color conversion processing refers to RGB color image data represented by a combination of R, G, and B gradation values, and an image represented by a combination of gradation values for each color of ink used for printing. This is the process of converting to data. As described above, the color printer 200 prints an image using four color inks of C,, ⁇ , and K. Therefore, in the color conversion processing of the first embodiment, the image data represented by each of the RGB colors is converted into data represented by the gradation values of each of the colors C,, ⁇ , and K. The color conversion process is performed by referring to a three-dimensional numerical table called a color conversion table (LUT).
- LUT three-dimensional numerical table
- the gradation values of each color of C, M, ⁇ , and K obtained by the color conversion for the RGB image data are stored in advance.
- RGB color image data can be rapidly converted into C, M, Y, and K image data.
- the resolution conversion processing is started (step S104).
- the resolution conversion process is a process of converting the resolution of the image data into a resolution at which the printer 200 prints an image (print resolution). If the resolution of the image data is lower than the print resolution, interpolation is performed to generate new image data between pixels.
- the computer # 100 starts the number data generation process (step S106).
- the number data generation process one image is divided into a plurality of pixel groups by grouping a predetermined number of adjacent pixels into a pixel group. Then, data representing the number of dots to be formed in each pixel group, that is, number data, is determined for each pixel group. In general, whether or not a dot is formed at a certain pixel depends on the image data of that pixel.
- the number data representing the number of dots formed in the pixel group is Can be determined based on the image data.
- the number data determined for each pixel group is output to the color printer 200.
- the count data generation process the count data is generated for each pixel group based on the image data of each pixel in this way, and then the color data is supplied to the color printer 200.
- the CPU incorporated in the control circuit 260 of the color printer 200 receives the number data supplied from the computer 100, it starts a pixel position determination process (step S108). Although the details of the processing will be described later, the following processing is roughly performed in the pixel position determination processing.
- the number data supplied from the computer 100 is data representing the number of dots to be formed in the pixel group, and the number of dots to be formed in which pixel in the pixel group is determined. Is uncertain It is in a stable state. Therefore, when printing an image, it is necessary to determine the pixel positions where dots are actually formed in the pixel group from the supplied number data.
- the pixel position determination processing an order indicating the ease of dot formation for each pixel in the pixel group, in other words, an order of pixels indicating the order in which dots are formed among a plurality of pixels in the pixel group is stored. By referring to this order, a process of determining pixel positions for forming dots based on the number data is performed.
- step SI10 a process of forming the dot at the determined pixel position is performed. That is, as described with reference to FIG. 3, the ink ejection head is driven to eject ink droplets while repeating the main scanning and the sub-scanning of the carriage 240, so that the ink is printed on the printing paper. Form dots. By forming the dots in this manner, an image corresponding to the entire image is printed. As described above, in the image printing process of the first embodiment, only the data of the number of dots to be formed in the pixel group is supplied from the computer 100 to the color printer 200.
- the number of dots formed in a pixel group obtained by combining a plurality of pixels can be expressed with a much smaller data amount.
- the number of dots formed in the pixel group can be any of nine from zero to eight. If there are 9 patterns, 4 bits can be used for expression, so the number of dots formed in a pixel group can be expressed with a data length of 4 bits. In this way, the number of dots formed in the pixel group can be represented by a much smaller amount of data than the data indicating the presence or absence of dot formation for each pixel. It is possible to supply data to the pudding 200 very quickly. In addition, as will be described in detail later, if the pixel positions for forming the dots are properly determined, the image quality does not deteriorate even when only the data of the number of dots is supplied.
- the dither method is a typical method used to convert image data into a data representing whether dots are formed or not for each pixel.
- a threshold value is set for a matrix called dither matrix, and the tone value of the image data is compared with the threshold value set in the dither matrix for each pixel to obtain the tone value of the image data.
- FIG. 6 is an explanatory diagram conceptually illustrating a part of the dither matrix.
- the matrix shown in the figure has 128 pixels in the horizontal direction (main scanning direction) and 64 pixels in the vertical direction (sub-scanning direction), for a total of 8192 pixels.
- the threshold value uniformly selected from the range of 255 is randomly stored.
- the reason why the gradation value of the threshold value is selected from the range of ⁇ to 255 is
- the image data is 1-byte data that can take gradation values of 0 to 255
- the gradation value of the image data is equal to the threshold value
- dots are formed only in pixels whose tone value of the image data is greater than the threshold value (that is, dots are not formed in pixels whose tone value is equal to the threshold value)
- Dots are never formed on pixels having the same threshold value as the maximum possible gradation value.
- a threshold can be taken
- the range is a range obtained by removing the maximum gradation value from the range that the image data can take.
- the range in which the threshold can be set is a range obtained by removing the minimum gradation value from the range in which the image data can be set.
- the possible gradation values of the image data are 0 to 255, and dots are formed in the pixels having the same threshold value as the image data. It is set to 5 5.
- the size of the dither matrix is not limited to the size as illustrated in FIG.
- FIG. 7 is an explanatory diagram conceptually showing a state in which the presence or absence of a dot shape is determined for each pixel while referring to a dither matrix.
- determining whether or not a dot is formed first, a pixel to be determined is selected, and the gradation value of the image data for this pixel is compared with a threshold value stored at a corresponding position in the dither matrix. I do.
- the thin dashed arrow shown in FIG. 7 schematically shows that the gradation value of the image data is compared with the threshold value stored in the dither matrix for each pixel. .
- the tone value of the image data is 97, and the threshold value of the dither matrix is 1, so that it is determined that a dot is formed in this pixel.
- the arrow indicated by the solid line in FIG. 7 schematically shows a state in which it is determined that a dot is formed in this pixel, and the result of the determination is written in the memory.
- the tone value of the image data is 97, and the threshold of dither matrix is 177, which is larger than the threshold. Therefore, no dot is formed for this pixel.
- FIGS. 8A to 8D are explanatory diagrams showing a state in which image data is converted into data indicating the presence or absence of dot formation using the dither method.
- Fig. 8a is an enlarged view of a part of the image data. The small rectangles in the figure represent the pixels, and the numerical values displayed in each rectangle represent the gradation values of the image data. ing. As shown, the image data tends to be assigned similar (or identical) tone values between adjacent pixels.
- FIG. 8b shows that the threshold is set at the corresponding position in the dither matrix.
- adjacent pixels are grouped by a predetermined number into a pixel group, and the number of pixels determined to form dots in the pixel group is counted.
- a pixel group consisting of 4 pixels in the main scanning direction (horizontal direction in Fig. 8a) and 2 pixels in the sub-scanning direction (vertical direction in Fig. 8a), for a total of 8 pixels each I do.
- FIG. 8d shows the number of dots obtained by counting the pixels determined to form dots for each of the pixel groups thus grouped.
- FIGS. 9a to 9d are explanatory diagrams showing how to generate data indicating the presence or absence of dot formation for each image from the number data.
- FIG. 9A shows a value obtained by counting the number of dots formed for each pixel group in FIG. 8D.
- FIG. 9B shows a dither matrix referred to in FIG. 8C to determine whether or not dots are formed for each pixel.
- the gradation value of the image data is compared with the threshold value set at the corresponding pixel position of the dither matrix, and if the gradation value of the image data is larger, It is determined that a dot is to be formed in a dot, and the smaller the threshold of dither matrix, the easier it is to form a dot. From this, it can be considered that the dither matrix represents the order of pixels in which dots are formed. Focusing on such properties of the dither matrix, it is possible to determine a pixel position where a dot is formed from the number of dots formed in the pixel group. For example, to explain the pixel group at the upper left corner shown in FIG.
- the number of dots formed in this pixel group is three.
- the pixel position at the upper left corner that is, the pixel position where the threshold value “1” is set, is the pixel where dots are most easily formed. It can be said that there is. Therefore, one of the three dots formed in this pixel group can be considered to be formed in the pixel at the upper left corner. Similarly, the remaining two dots are the second most likely to form dots in this group of pixels (ie, the pixels for which the threshold ⁇ 42 in the dither matrix of FIG.
- a dot is formed on a pixel where a dot is likely to be formed (that is, a pixel for which the threshold value “58” is set).
- the presence or absence of dot formation is affected not only by the threshold value set in the dither matrix, but also by the gradation value of the image data, so if the gradation value of the image data is extremely large,
- a dot may be formed before a pixel for which a smaller threshold is set.
- image data tends to be assigned an approximate (or the same) gradation value to adjacent pixels. Therefore, in most cases, pixels in which dots are easily formed (that is, pixels in a dither matrix) are used. It can be considered that a dot is formed from (a pixel having a small set threshold value).
- the pixel positions at which dots are formed can be determined based on the number of dots and the threshold value of dither matrix. For example,
- the number of dots is three, so referring to the dither matrix in Fig. 9b,
- the three dots are a pixel with a threshold of “2 2”, a pixel with a threshold of “3 3”,
- the pixel is formed for each of the pixels for which the threshold “91” is set.
- the results shown in FIG. 9C can be obtained.
- the hatched pixels are pixels determined to form dots.
- the pixel position determined from the number data coincides with the pixel position determined for each pixel. This means that the presence or absence of dot formation is determined for each pixel with reference to the dither matrix, and the dot formed in the pixel group is determined.
- the result of comparing the tone value of the image data with the threshold value of the dither matrix to determine the presence or absence of dot formation for each pixel is completely the same as that of the pixel. It is guaranteed that a dot can be formed at the position.
- the first condition is that the gradation value of each pixel has the same value in the pixel group
- the second condition is whether or not dot formation is performed for each pixel on the computer 100 side.
- the dither matrix referred to when judging is the same as the dither matrix referenced to determine the pixel position from the number data on the color printer 200 side. In the dither method described with reference to FIG.
- the threshold value set in the dither matrix and the gradation value of the image data are compared, and the presence or absence of dot formation is determined based on which value is larger. Deciding.
- the explanation has been given using FIGS. 9a to 9d. In this way, the pixel positions at which dots are formed are determined in order from the pixel with the smallest threshold set in the dither matrix. That is, in order to determine the pixel position, it is not necessary to reach the threshold value, but it is sufficient that the order in which dots are easily formed in the pixel group is known. Therefore, instead of the dither matrix shown in Fig.
- a matrix in which values (order values) indicating the order in which dots are formed are set for each pixel in the pixel group as shown in Fig. 9d.
- a matrix is referred to as an order matrix.
- a pixel position is determined from the number data while referring to the order matrix for each pixel group. It is also possible.
- FIG. 10 is a flowchart illustrating the flow of the count data generation process according to the first embodiment.
- the description will be made assuming that the number data generation process is performed by the computer 100.
- the number data generation process can be an extremely simple process. It is also possible to carry out in the digital camera 120.
- description will be given according to the flowchart.
- the pixels to be grouped as a pixel group do not need to be pixels in which the vertical and horizontal positions are aligned in a rectangular shape as described above. good.
- a pixel group classification number and a pixel group gradation value are determined (step S202). The classification number of the pixel group can be determined extremely easily by using a method described later. Also,
- the pixel group gradation value can also be easily determined as follows. For example, the average value of the tone values assigned to each pixel in the pixel group can be obtained and used as the pixel group tone value, or the tone value assigned to the most pixels in the pixel group Further, the gradation value of a pixel at a specific position in the pixel group can be used as the pixel group gradation value.
- the number data is determined by referring to a conversion table described later (step S204). As will be described in detail later, in the conversion table, appropriate number data is stored in advance in association with the combination of the pixel group classification number and the pixel group gradation value.
- the number data can be immediately obtained by referring to the conversion table. This point will be explained in detail later.
- the process returns to step S200 to generate a new pixel group and repeat a series of subsequent processes. These operations are repeated, and when it is determined that the processing has been completed for all the pixels (step S206: yes), the number data obtained for each pixel group is output to the color printer 200 (step S202).
- FIG. 11a to FIG. 11c are explanatory diagrams showing a concept for determining a classification number for each pixel group.
- Fig. 11a conceptually shows how one pixel group was generated by combining 8 pixels in total at the upper left corner of the image, 4 pixels in the horizontal direction and 2 pixels in the vertical direction. Things.
- the gradation value of the image data assigned to the pixel is compared with the threshold value set at the corresponding position in the dither matrix, and the presence or absence of dot formation is determined for each pixel.
- a predetermined number of adjacent pixels are grouped together as a pixel group, so that the thresholds set in the dither matrix are generated by grouping the predetermined number of pixels corresponding to the pixel group together.
- FIG. 11b shows a state in which the thresholds set for the dither matrix shown in FIG. 6 are generated in groups of four in the horizontal direction and two in the vertical direction to generate a plurality of blocks.
- the dither matrix is divided into 32 blocks in each of the vertical and horizontal directions, for a total of 10 24 blocks. Now, as shown in FIG. 11b, these blocks are numbered sequentially from No. 1 to No. 124. Then, when dither matrix is applied to the image data, the pixel groups are classified according to the serial number of the block applied to the position of each pixel group. For example, as shown in Fig. 11c, the block with the serial number 1 in Fig. 11b is applied to the pixel group at the upper left corner of the image. It is classified into pixel groups.
- step S202 of FIG. 10 when dither matrix is applied to the image data, each pixel group is classified by the serial number of the block applied to the pixel group, and the corresponding classification number is A process of deciding and giving it to the pixel group is performed.
- FIGS. 12a to 12d are explanatory diagrams showing a method of determining the classification number of a pixel group.
- FIG. 12a shows one pixel group generated in the image.
- a method of determining a classification number by focusing on this pixel group will be described.
- the pixel group of interest for determining the classification number will be referred to as the pixel group of interest.
- the pixel at the upper left corner of the image is taken as the origin, and the pixel position is represented by the number of pixels in the main scanning direction and the sub-scanning direction from the origin.
- the position of the pixel group is represented by the pixel position of the pixel at the upper left corner of the pixel group.
- pixels indicating the position of the pixel group of interest are indicated by black circles. Assume that the pixel position of this pixel is (X, Y). Then, since the size of each pixel group is 4 pixels in the main scanning direction and 2 pixels in the sub scanning direction,
- n pixel groups are arranged on the left side of the pixel group of interest, and m pixel groups are arranged above the pixel group of interest.
- the pixel group is obtained by applying dither matrix to the image data.
- the classification is based on the serial number of the block applied to the pixel group of interest (see Figs. 11a to 11c). Thus, the same pixel group is classified into different classification numbers.
- any method can be applied to the image data while moving the dither matrix, but here, for convenience of explanation, the simplest method, namely, moving the dither matrix in the horizontal direction is also used. It will be described as.
- Fig. 12b conceptually shows how dither matrix is applied to image data repeatedly while moving it little by little in the horizontal direction.
- Fig. 12c conceptually shows how dither matrices are applied to the pixel group of interest shown in Fig. 12a while using dither matrices repeatedly as shown in Fig. 12 b.
- the dither matrix is moved in this manner, one of the blocks in the dither matrix is applied to the target pixel group.
- the block of the M-th row and the N-th column in the dither matrix is applied to the target pixel group.
- n pixel groups on the left side of the pixel group of interest there are n pixel groups on the left side of the pixel group of interest and m pixel groups on the upper side, so that between N and n and between M and m Respectively
- N n-i n t (n / 3 2) X 3 2 + 1
- int is an operator indicating that a value after the decimal point is truncated to be converted to an integer. That is, int (n / 3 2) represents an integer value obtained by truncating the value after the decimal point from the calculation result of ⁇ ⁇ 32.
- M and N are obtained from the above-described relational expression shown in FIG. It may be used as the classification number of the pixel group of interest.
- the values of M and N can be extremely small without performing calculations as shown in Figure 12d. Can be obtained easily. Hereinafter, this point will be described.
- FIG. 13 is an explanatory diagram specifically showing a method of determining the classification number of the pixel group of interest. Assume that the position of the pixel group of interest is (X, Y), and that X and Y are represented by ⁇ 0 bits.
- FIG. 13A conceptually shows 10-bit binary data representing the numerical value X. In the figure,
- a serial number from 1 to 10 is assigned from the most significant bit to the least significant bit.
- the number n of pixel groups on the left side of the pixel group of interest can be obtained by subtracting 1 from the numerical value X and dividing by 4.
- the division by 4 can be performed by shifting rightward by 2 bits, so that 1 is subtracted from the numerical value X, and the obtained binary data is 2 bits rightward. It is sufficient to shift the bits by a fraction.
- the numerical value X does not take an arbitrary value, it can only take a numerical value that can be expressed in the form of 4 n + 1, so without subtracting ⁇ , simply binary data is divided into two bits to the right. Just make it bit shift,
- the number n of pixel groups can be obtained.
- Fig. 13 (b) conceptually shows the number n of binary numbers obtained by bit-shifting the numerical value X in this way.
- int (n / 32) is calculated. That is, the operation of dividing the number n by 32 and rounding down the number after the decimal point is performed. Division by 32 can be performed by shifting the binary data bitwise by 5 bits to the right. I will.
- int (n / 32) binary data can be obtained by simply shifting the number n of binary data by 5 bits to the right.
- Figure 13 (c) shows the binary data of int (n / 32) obtained by bit-shifting the number n. The int (nZ32) obtained in this way is multiplied by 32.
- FIG. 13 (d) conceptually shows binary data of int (n / 3 2) X 32 obtained by bit-shifting the number n. Then, subtracting int (n / 32) X 32 from the number n yields the numerical value N described above.
- the binary data of the number n see Fig. 13 (b)
- the binary data of ⁇ nt (n / 32) X 32 see Fig. 13 (d)
- the upper 5 bits are common, and the lower 5 bits of the value on the subtraction side are all “0”. Therefore, if the lower 5 bits of the value to be subtracted (number n) are extracted as they are,
- the numerical value N can be obtained extremely simply by applying the mask data shown in Fig. 13 (.f) to the binary data shown in Fig. 13 (b). is there.
- the mask data shown in Fig. 13 (g) is applied to the binary data of the numerical value X indicating the position of the pixel group of interest shown in Fig. 13 (a), and the fourth to eighth bits are applied.
- the numerical value N can also be obtained by directly extracting the data. In FIG. 13, the case where the numerical value N indicating the block position in the dither matrix is obtained from the numerical value X of the coordinate value (X, Y) indicating the position of the pixel group of interest has been described. Can be obtained from the numerical value Y.
- the serial number of this block allows the pixel of interest As described above with reference to FIG. 10, the group number of the group can be quickly determined.
- the classification number and the pixel group of the pixel group thus obtained are obtained.
- the number data is obtained from the gradation values by referring to the conversion table (see step S204 in FIG. 10). In the following, a description will be given of a conversion table referred to in order to obtain the quantity data.
- FIG. 14 is an explanatory diagram conceptually showing a conversion table referred to to acquire the number data from the pixel group classification number and the pixel group gradation value.
- appropriate number data is stored in advance in association with the combination of the pixel group classification number and the pixel group gradation value.
- FIG. 15 is an explanatory diagram conceptually showing a state in which an appropriate number is determined in accordance with a combination of a pixel group classification number and a pixel group gradation value.
- the classification number of the pixel group is No. 1.
- the block with the serial number 1 in the dither matrix is applied to the pixel group with the classification number "I incense.
- Figure 15 (a) shows the threshold set for the port with the serial number 1
- the pixel group gradation value is 0.
- the gradation value of each pixel Ie
- FIG. 15 (b) conceptually shows how the number data is determined when the pixel group gradation value is 0. In this case, no dot is formed at any of the pixels in the pixel group, and thus the number data becomes zero.
- FIG. 15 (c) conceptually shows how the number data is determined when the pixel group gradation value is one. In this case, assuming that all the pixels in the pixel group have image data with a gradation value of 1, the gradation value of each pixel is compared with the threshold value shown in FIG. 5 (a). As a result, in the pixel at the upper left corner in the pixel group, it is determined that the tone value of the image data and the threshold value are equal to form a dot,
- the number data 1 is set for the combination having the classification number 1 and the pixel group gradation value 1.
- the number data is determined. For example, when the pixel group gradation value is 2, the count data becomes ⁇ as shown in FIG. 15 (d), and when the pixel group gradation value is 100, FIG. 15 (e) As shown in the figure, the number data is 3.
- FIGS. 15 (c) When the pixel group gradation value is 2, the count data becomes ⁇ as shown in FIG. 15 (d), and when the pixel group gradation value is 100, FIG. 15 (e) As shown in the figure, the number data is 3.
- 15 (f) and 15 (g) show that the number data is determined when the pixel group gradation value is 200 and the pixel group gradation value is 255. Is conceptually shown.
- Figure 14 In the row corresponding to the class number 1 (horizontal column shown in the table), the number of data set in association with each pixel group gradation value is determined in this manner. This is count data. If this operation is performed for all the classification numbers from No. 1 to No. 124, finally, the number data corresponding to all combinations of all the classification numbers and all the pixel group gradation values is determined. can do.
- corresponding number data is set in advance according to the combination of the classification number and the pixel group gradation value.
- FIG. 16 is a flowchart showing the flow of the pixel position determination process of the first embodiment. This process is a process executed by the CPU incorporated in the control circuit 260 of the color printer 200. In the following, referring to the flow chart shown in FIG.
- step S300 one pixel group to be processed is selected (step S300), and the number data of the pixel group is obtained (step S302).
- step S302 it is assumed that the number data as shown in FIG. 9A has been supplied. It is assumed that the pixel group at the upper left corner in FIG. 9A is selected as the pixel group to be processed. in this case,
- step S302 of FIG. 16 "3" is obtained as the number data of the selected pixel group.
- a pixel position where a dot is formed in the pixel group is determined by referring to the order matrix (step S304).
- the order matrix is a matrix indicating the easiness of dot formation for each pixel in the pixel group.
- the pixel group to be processed is the pixel group at the upper left corner in the image, and therefore the order matrix is also the matrix at the corresponding location (that is, the 8 pixels at the upper left corner in Fig. 9d). Matrix).
- the quantity data is "3"
- the pixel position forming the dot is the pixel at the upper left corner and the two pixels to the right Pixel and the lower right pixel.
- the pixels where the dots are formed are indicated by diagonal lines.
- the pixel position at which a dot is to be formed is determined based on the number data while referring to the order matrix in this manner.
- the description has been made assuming that the pixel position is determined with reference to the order matrix.
- the dither matrix is the same as the order matrix in that the order of each pixel in the pixel group is indicated. Therefore, it goes without saying that a dither matrix may be referred to instead of the order matrix.
- a dither matrix may be referred to instead of the order matrix.
- step S306 when the processing has been completed for all the pixel groups (step S306: yes), the pixel position determination processing shown in FIG. 16 is completed, and the processing returns to the image printing processing shown in FIG.
- the details of the number data generation processing (step S106 in FIG. 5) and the pixel position determination processing (step S108 in FIG. 5) performed during the image printing processing of the first embodiment are described above in detail. did.
- a pixel group is generated by grouping a predetermined number of pixels, and a classification number and a pixel group gradation value are determined for the pixel group, and then the number data is generated.
- the pixel group classification number and the pixel group gradation value can be obtained very easily as described above.
- the number table can be generated extremely easily by referring to the conversion table described above.
- the quantity data generated in this way has a much smaller amount of data than data representing the presence or absence of dot formation for each pixel. Data can be output very quickly. That is, in the above-described number data generation processing, the generation and output of the number data can be performed at high speed, and the image can be printed quickly by that amount.
- the process of generating the count data is not merely a process of referring to the conversion table, and the classification number and pixel group gradation value used to refer to the conversion table can be obtained by extremely simple processing.
- processing can be performed at a sufficiently practical speed even when a device such as a computer 100 that does not have high data processing capability is used. Furthermore, since the processing content is extremely simple, most of the processing is performed not by software using a CPU but by hardware using an IC chip incorporating a dedicated logic circuit. It is easy to do this, and it is possible to process at extremely high speed. Therefore, even when a device that generates image data such as a digital camera 120 and a color printer 200 are directly connected, the count data generation processing is performed inside the digital camera 120 and the color printer 200. By doing so, it is also possible to print images quickly.
- FIG. 17 is an explanatory diagram showing the results of trial calculation of the data size of the conversion table under various conditions. As shown in Fig.
- the number data is set for each combination of the classification number and the pixel group gradation value, so the data size of the conversion template is It is determined by the number, the range of possible pixel group gradation values, and the data length per piece of number data.
- the number of classification numbers is equal to the number of blocks generated by dividing the dither matrix, and is ultimately determined by the size of the dither matrix and the size of the pixel group.
- the size of the dither matrix is 64 ⁇ 64 (ie, 64 pixels in the main scanning direction and 6 pixels in the sub-scanning direction).
- ⁇ 28 x 64 (128 pixels in the main scanning direction, 64 pixels in the sub-scanning direction), 128 x 128 (128 pixels in the main scanning direction, 128 in the sub-scanning direction) It is assumed that there are three sizes of (1 2 8 pixels).
- the pixel group sizes are 2 x 2 (2 pixels in the main scanning direction, 2 pixels in the sub-scanning direction), 4 x 2 (4 pixels in the main scanning direction, 2 pixels in the sub-scanning direction), 4 x 4 (4 pixels in the main scanning direction,
- the pixel group gradation value can take 256 values from 0 to 255, and that the data length of the number data is 1 byte.
- the dither matrix size is 128 ⁇ 64
- the pixel group size is 4 ⁇ 2
- the trial calculation result is shown in FIG. It is shown.
- the calculation result of the conversion table size will be described using this condition as a representative example.
- the number of blocks is the number of blocks obtained by dividing the dither matrix into the same size as the pixel group.
- the pixel training (128 ⁇ 64) of the dither matrix is calculated by dividing the number of pixels per pixel group (4 X 2) divides by 10 24.
- This value is the number of classification numbers in the conversion table.
- the pixel group tone value can take 256 values from 0 to 255, so the combination of the classification number and the pixel group tone value is 10 24 X 25
- the data amount of the conversion table is eventually calculated to be 256 bytes. As is clear from the above calculation method, the data amount of the conversion table tends to increase as the size of the dither matrix increases and the number of classification numbers increases. "Mouth ⁇ 1 (this,
- the data amount of the conversion table tends to increase.
- the size of the conversion table is about 64 x 64 to 128 x 128, so from the calculation results shown in Fig. 17, the data amount of the conversion table is 1 M except for extremely special cases. It does not exceed the byte, and it is about 256 KB! ⁇ ⁇ It is about 512 KB.
- a matrix larger than the dither matrix used in the estimation in Fig. 17 may be used, but even in this case, the amount of data in the conversion table will not be large enough to reduce the memory capacity. .
- the column labeled “Number of states Z pixel group” in the second column from the right end indicates the number of states that the pixel group can take (that is, the type of number of dots that can be formed in one pixel group).
- the number of bits required to represent the number of states is shown in the column labeled “Number of bits used” at the right end.
- the number data is 1-byte data
- the smaller the size of the pixel group the larger the data amount of the conversion table.
- the smaller the size of the pixel group the smaller the number of bits used. Therefore, the reduction rate of the data amount in consideration of this point increases.
- the amount of data in the conversion table is even smaller than the result of the trial calculation in Fig. 17, and it is considered that a maximum of about 256 KB is sufficient in practice.
- the data amount of the color conversion table (LUT) referred to in the color conversion process (step S102 in FIG. 5) during the above-described image printing process is usually 1.5 M or more, The data volume of 56 Kbytes is not a large data volume.
- FIG. 18 is a flowchart showing a flow of an image printing process according to a modification of the first embodiment.
- the image printing process of the modified example is different from the image printing process of the first embodiment shown in FIG. 5 in that the resolution of the image data is not converted to the printing resolution, but the data having a lower resolution than the printing resolution is used. There is a great difference between the point that conversion is made and the point that pixel groups are not explicitly formed in the count data generation process, but the other points are almost the same.
- the image printing process according to the modified example will be described focusing on the difference from the image printing process according to the first embodiment.
- the image printing process of the modified example similarly to the image printing process of the first embodiment, when the process is started, first, the image data is read (step S400), and the color conversion process is performed (step S4). 0 2).
- FIGS. 19a to 19c are explanatory diagrams showing the processing performed in the resolution adjustment processing.
- FIG. 19a conceptually illustrates image data after color conversion
- FIG. 19b conceptually illustrates image data generated by the resolution adjustment processing.
- FIG. 19c shows image data of the print resolution.
- the image data generated by the resolution adjustment processing has lower resolution than the printing resolution. More specifically, the resolution of the image data generated by the resolution adjustment process is 1/4 of the printing resolution in the main scanning direction and 1/2 of the printing resolution in the sub scanning direction.
- the pixels generated by the resolution adjustment process are four times larger in the main scanning direction and twice as large in the sub-scanning direction as the pixels with the printing resolution shown in Fig. 19c. Converted to pixels.
- the resolution adjustment process of the modified example the resolution of the image data is converted so that the size of one pixel after the resolution conversion matches the size of the pixel group generated by collecting the printing resolution pixels. Yes, it does the processing.
- the number data generation process is started after the resolution of the image data after the color conversion is adjusted in this way (step S406 in FIG. 18).
- step S500 one pixel to be processed is selected (step S500).
- the pixel selected here is a pixel larger than the pixel of the printing resolution as shown in FIG. 9B. However, the size of this pixel matches the size of the pixel group generated by combining the pixels of the print resolution in the first embodiment described above. Then, the selected pixel is treated as if it were a pixel group in the first embodiment, and the classification number for this pixel is determined (step S502).
- the classification number can be determined according to the method in the first embodiment by replacing the pixel groups in FIGS. 11a to 13 with pixels. Next, by referring to the conversion table shown in FIG.
- the number data for the selected pixel is obtained (step S504).
- the gradation value of the image data assigned to the selected pixel can be used as it is. In this way, when the number data is obtained for the pixel selected as the processing target, it is determined whether or not the processing has been completed for all the pixels (step S506). Untreated If there is any pixel remaining (step S506: no), the process returns to step S500 to select a new pixel to be processed, and then performs a series of subsequent processes. These operations are repeated, and when it is determined that the processing has been completed for all pixels (step S506: yes), the number data obtained for each pixel is output to the color printer 200 (step S508).
- the number data generation process of the modification shown in FIG. 18 ends. Subsequent to the above-described number data generation processing, a pixel position determination processing is performed (step S408).
- the pixel position determination processing is the same as the image printing processing of the first embodiment described above in the image printing processing of the modified example. That is, the number data supplied from the computer 100 is received, and the pixel position where a dot is formed in the pixel group is determined by referring to the order matrix. Next, dots are formed at the pixel positions thus determined (step S410).
- the number data can be generated while the image data is data having a resolution lower than the printing resolution.
- the resolution decreases, the amount of image data decreases, so that the data can be handled quickly and the amount of memory temporarily required for processing can be reduced.
- simplification and speeding up of the process can be realized at the same time.
- high-resolution printing is effective for printing high-quality images, but it is not always necessary to increase the resolution of image data in accordance with the increase in printing resolution. It is not necessary. It is possible to improve print quality by simply receiving low-resolution image data and simply dividing large pixels into smaller pixels and increasing the apparent resolution. For example, low-resolution image data as shown in FIG. 19b is received, each pixel is divided into a plurality of pixels, and converted into a high-resolution image data as shown in FIG. 19c. In the image data obtained in this way, the apparent resolution is higher, but it is not possible to achieve a smooth gradation change corresponding to the resolution, and from the viewpoint of expressing the gradation change smoothly. There is no difference from low resolution image data.
- image data can represent multiple gradations for individual pixels. For example, when the image data is one byte data, 256 gradations can be expressed per pixel. On the other hand, when printing an image by forming dots, each pixel can take only two passes, whether or not to form a dot. The number of gradations that can be expressed per area is only a few at most. In other words,
- the image printing process of the modified example can be suitably applied to a case where image data of low resolution is received and an image is printed after the apparent resolution is increased.
- the resolution is adjusted as necessary, and then the individual pixels are treated as if they were a group of pixels, and the number data is generated.
- the size of the pixels of the received image data matches the size of the pixel group, the number data of each pixel can be generated as it is without adjusting the resolution. It is possible to print an image on a computer.
- the dot that can be formed by the color printer 200 is described as one type. But today, with the goal of improving print quality,
- Printers that can form various types of dots, such as dots with different sizes and dots with different ink densities, are widely used.
- the invention of the present application can provide a great effect even when applied to such multi-value dot printing.
- a second embodiment a case where the present invention is applied to a multi-valued dot printing will be described.
- the image printing process of the second embodiment is the same as the image printing process of the first embodiment shown in FIG. 5 for the flowchart.
- an outline of the image printing process of the second embodiment will be briefly described by using the flowchart of FIG.
- the image printing process of the second embodiment is started, first, the image data is read by the computer 100, and then the color conversion process is performed (corresponding to steps S100 and S102 in FIG. 5). .
- a resolution conversion process is performed to convert the resolution of the image data into a print resolution (corresponding to step S104), and then the number data generation process is started (corresponding to step S106).
- the color printer 200 can form only one type of dot.
- the number data generation process the number data representing the number of dots formed in the pixel group was generated for each pixel group and output to the color printer 200.
- the number data generation process the number data representing the number of dots formed in the pixel group was generated for each pixel group and output to the color printer 200.
- the color printer 200 can form three types of dots having different sizes, that is, large dots, medium dots, and small dots.
- number data indicating how many large dots, medium dots, and small dots are formed in each pixel group is generated. It will be. Although details will be described later, in order to efficiently output the number data with a small data amount, the number of large dots, medium dots, and small dots is not output as it is, but is output in a coded state. The details of the count data generation processing of the second embodiment will be described later.
- the CPU incorporated in the control circuit 260 of the color printer 200 receives the number data supplied from the computer 100, it starts a pixel position determination process (corresponding to step S108 in FIG. 5). .
- the number data supplied in a coded state is decoded into data indicating the number of large dots, medium dots, and small dots. After that, the pixel positions for forming these dots are determined. After determining the pixel positions at which various large, medium and small dots are to be formed, dots are formed at the determined pixel positions (corresponding to step S110 in FIG. 5). By forming a large dot, a medium dot, and a small dot in this way, an image corresponding to the image data is printed.
- the process of generating the number data in which the number of medium dots and small dots is coded will be described.
- the coded number data can be generated very easily by referring to the conversion table based on the pixel group classification number and the pixel group gradation value.
- a brief description will be given of a process of determining the number of large, medium, and small dots formed in a pixel group using a so-called dither method.
- a process of encoding the number of large, medium, and small dots will be described, and then, a detailed process performed in the number data generation process of the second embodiment will be described.
- FIG. 21 is a flowchart showing the flow of processing for determining the number of large dots, medium dots, and small dots formed in a pixel group by applying the dither method.
- the details of this processing are disclosed in Japanese Patent No. 3292210. Therefore, the processing shown in FIG. 29 can be regarded as a method in which the method disclosed in Japanese Patent Laid-Open No. 3922104 is performed for each pixel group.
- the number of large, medium, and small dots is determined, first, when the process is started, a predetermined number of pixels adjacent to each other are grouped to form a pixel group (step S600).
- a total of eight pixels that is, four pixels in the main scanning direction and two pixels in the sub-scanning direction, are collected as a pixel group.
- one pixel to be processed is selected (step S602) to determine whether or not to form a dot from the pixel group, and a large dot, a medium dot, and a small dot are selected for the selected processed pixel.
- the presence or absence of the formation is determined (step S604).
- the presence or absence of large, medium and small dots is determined as follows.
- FIG. 22 is a flowchart showing the flow of a process for determining whether or not large dots, medium dots, and small dots are to be formed by performing a half-I-one process on one selected pixel.
- the image data of the pixel to be processed is converted into density data of each dot of large dot, medium dot, and small dot (Step S65) 0).
- the density data is data indicating the density of dots to be formed.
- the density data indicates that the higher the gradation value, the higher the density of dots formed.
- the gradation value “255” of the density data indicates that the dot formation density is 100%, that is, that dots are formed in all pixels.
- a tone value of “0” indicates that the dot formation density is 0%, that is, no dot is formed at any pixel. Conversion to such density data can be performed by referring to a numerical table called a dot density conversion table.
- the dot density conversion table shows the density data for each of the small dot, medium dot, and large dot with respect to the gradation value of the image data obtained by color conversion. Is set. In the region where the image data is in the vicinity of the gradation value “0”, the density data of the medium dot and the large dot are both set to the gradation value “0”. The density data of small dots increases as the gradation value of the image data increases. When the image data reaches a certain gradation value, it starts to decrease this time,
- the density data of the medium dot begins to increase.
- the density data of the small dot becomes the gradation value “0”
- the density data of the medium dot starts to decrease, and instead, the large dot becomes large dot. Density data will gradually increase.
- the gradation value of the image data is converted into large dot density data, medium dot density data, and small dot density data while referring to this dot density conversion table. I do.
- step S654 This judgment is made by comparing the density data of the large dot with the threshold value of the dither matrix set at the corresponding position of the pixel to be processed. If the density data is larger, it is determined that a large dot is formed at the pixel to be processed (step S654: yes), and the process exits the half-toning process and is shown in FIG. The process returns to the number of dots determination process. Conversely, if the threshold value is larger than the large dot density data, it is determined that a large dot is not formed at the pixel to be processed (step S654: n0), and this time the middle dot is used. The process of determining the presence or absence of a bird is started.
- the density data of the large dot and the density data of the medium dot are added to calculate intermediate data for the medium dot (step S656). Then, the presence or absence of the formation of the medium dot is determined by comparing the obtained middle data for the medium dot with the threshold value of the dither matrix (step S6585). And
- step S660 If the intermediate data for the middle dot is larger, it is determined that a middle dot is to be formed in the pixel to be processed (step S660: yes), and the process exits the half-toning process. The process returns to the dot number determination process of 1. Conversely, if the threshold value is larger than the middle dot for the middle dot, it is determined that no middle dot is formed at the pixel to be processed (step S660: no), and the small dot is The process of determining the presence or absence of a bird is started. To determine whether or not a small dot is formed, the intermediate data for the medium dot and the density data for the small dot are added to calculate the intermediate data for the small dot (step S6662).
- the presence / absence of small dots is determined by comparing the obtained intermediate data for small dots with the threshold value of dither matrix (step S6664). If the intermediate data for the small dot is larger, it is determined that a small dot is formed at the pixel to be processed. Conversely, if the threshold is larger than the intermediate data for the small dot, Judge that neither dot is formed.
- the process returns from the halftone process shown in FIG. 22 to the dot number determination process shown in FIG.
- FIG. 24 is an explanatory diagram conceptually showing a state in which the presence or absence of large, medium, and small dots is determined for each pixel in the pixel group while applying the dither method.
- all the pixels in the pixel group have the same gradation value, and therefore, the density data of each of the large, medium and small dots has the same gradation value.
- Figure 24 (a) shows the density data of large, medium, and small dots obtained for each pixel in the pixel group.
- the density data of the large dot is “2” and the density data of the medium dot is Assume that “90” and the density data of the small dots are “32 j.”
- Figure 24 (b) is stored in the dither matrix at the position corresponding to the pixel group. Represents a threshold value. When determining whether or not a large dot is formed, the density of the large dot is compared with these thresholds. Here, it is assumed that the density data of the large dot is “2” for any of the pixels. Therefore, the only pixels that are determined to form a large dot are pixels for which the threshold value “1” is set. In Fig. 24 (b), the pixels determined to form large dots are:
- the intermediate data for medium dots is calculated by adding the density data “2” of the large dots and the density data “90” of the medium dots. 9 2 ”and the dither matrix threshold. As a result, it is determined that a medium dot is formed only in two pixels, a pixel for which the threshold value “4 2” is set and a pixel for which the threshold value “5 8” is set. In FIG.
- pixels for which it is determined that a medium dot is to be formed are displayed with slightly fine diagonal lines. Then, for a pixel in which neither a large dot nor a medium dot is formed, it is considered that either a small dot is formed or a dot is not formed.
- the small dot density data “3 2” is added to the intermediate data “9 2” for the medium dot
- the intermediate data for the small dot is calculated, and the obtained intermediate data “1 24 J” is compared with the threshold of the dither matrix. As a result, only the pixel for which the threshold ⁇ 09 is set is small dot. Is determined to be formed. In FIG. 24 (d), pixels for which small dots are determined to be formed are indicated by coarse diagonal lines.
- steps S602 to S606 of the number-of-dots determination process shown in Fig. 2 ⁇ the intermediate data is calculated for each pixel in the pixel group as described above, It is determined whether dots are formed. When the determination is completed for all pixels in the pixel group (step S606res), the number of large dots, medium dots, and small dots formed in the pixel group is obtained (step S6).
- the pixel group shown in Fig. 24 has one large dot, two medium dots, and one small dot.
- it is determined whether or not the above processing has been performed on all the pixels of the image (step S610). If unprocessed pixels remain, the process returns to step S600 to repeat a series of processes. If it is determined that the process has been completed for all pixels of the image, the process proceeds to step S600.
- the process of determining the number of dots by the dither method ends. As a result, the image data is divided into a plurality of pixel groups, and the number of large dots, medium dots, and small dots formed in each pixel group is obtained.
- Figure 25 shows a large dot for each pixel group.
- the obtained number of dots is output to the printer in a coded state.
- the number of dots for each pixel group is calculated three times. Must be output. In this case, the effect of rapidly outputting an image from the computer 100 to the color printer 200 to quickly print an image is diminished. Therefore, instead of outputting the number of each dot individually, a combination of the numbers of each dot, for example, a combination of (K large dots, L medium dots, and N small dots) is set for each combination.
- FIG. 26 is an explanatory diagram showing a correspondence table in which a combination of the numbers of large, medium, and small dots formed in a pixel group is set in association with a code sequence.
- the correspondence table illustrated in FIG. 26 for example, for a combination in which the number of large dots, medium dots, and small dots is 0,
- Code data “0” is associated.
- a combination of 0 large dots, 0 medium dots, and 1 small dot is associated with code data “1”.
- unique code data is set in advance for each combination of the number of dots.
- the combination number of the large, medium and small dots is as follows. Each of the pixels in the pixel group can form a large dot, a medium dot, or a small dot.However, since a single pixel does not have multiple dots, the total number of dots is The number of pixels does not exceed (8 in the above embodiment). Therefore, the combination of the numbers of these large, medium, and small dots overlaps among the four states of "form large dots", “form medium dots”, “form small dots", and "do not form dots”. Is equal to the number of combinations when selecting eight times,
- n H r is an operator for calculating the number of combinations (the number of overlapping combinations) obtained when selecting r times from n types of objects while allowing duplication.
- N C r is an operator for calculating the number of unions obtained when r selections are made r times from n types of objects without allowing duplication. It means that there are 1 65 combinations of the number of large, medium, and small dots as shown in the following. 1 6 5 ways If there is, it can be expressed if there is an 8-bit data length. After all, instead of outputting three times, the number of large dots, the number of medium dots, and the number of small dots, only one output of 8-bit coded number data is performed, and various dots are formed in the pixel group.
- FIG. 27 is a flowchart illustrating the flow of the count data generation process according to the second embodiment.
- the number data generation processing of the second embodiment is also performed by the computer 100.
- the number data generation processing of the second embodiment is extremely simple. Since the processing can be performed, the processing can be performed in the color printer 200 or the digital camera 120.
- Floatia When the number data generation process according to the second embodiment is started, which will be described first, first, a predetermined number of pixels adjacent to each other are grouped to generate a pixel group (step S700).
- a pixel group classification number and a pixel group gradation value are determined (step S702).
- the method of determining the pixel group classification number and the pixel group gradation value is the same as that of the first embodiment described above, and thus the description is omitted here. However, both the classification number and the pixel group gradation value are extremely simple. You can decide. Next, by referring to the conversion table from the pixel group classification number and the pixel group gradation value,
- FIG. 28 is an explanatory diagram conceptually showing a conversion table referred to in the count data generation processing of the second embodiment.
- the conversion table of the second embodiment stores in advance coded number data in association with the combination of the pixel group classification number and the pixel group gradation value. Therefore, in the count data generation processing of the second embodiment, the count data in a coded state is determined immediately by simply determining the pixel group classification number and the pixel group gradation value and referring to the conversion table. It is possible.
- the coded number data for one pixel group is obtained, it is determined whether or not the processing has been completed for all the pixels of the image data (step S 706).
- step S706 If unprocessed pixels remain (step S706: n0), the process returns to step S700 to generate a new pixel group, and repeats a series of subsequent processes. These operations were repeated, and it was determined that processing for all pixels was completed. (Step S 706: yes), the coded number data obtained for each pixel group is output to the color printer 200 (Step S 708), and the second data shown in FIG. The number data generation process of the second embodiment ends.
- C-1 Pixel position determination processing of the second embodiment:
- FIG. 9 is a flowchart illustrating a flow of a pixel position determination process according to the second embodiment.
- This processing differs from the pixel position determination processing of the first embodiment described above with reference to FIG. 16 in that the number data is decoded and converted to data indicating the number of large, medium, and small dots to be formed. The difference is that the pixel position is determined for each of the small and medium dots.
- the pixel position determination process of the second embodiment will be described while focusing on these differences.
- FIG. 30 is an explanatory diagram conceptually showing a decoding table referred to for decoding the number data coded in the pixel position determination processing of the second embodiment.
- the decoding table combinations of dot numbers of large dots, medium dots, and small dots corresponding to the coded number data are set. For example, if the coded quantity data is “1”, the large dot and medium dot The number is 0, and it is decoded to a combination of the number of dots where the number of small dots is 1.
- step S804 of FIG. 29 the encoded number data is converted into data representing the number of large, medium, and small dots by referring to such a decoding table.
- step S800 the order matrix stored at the position corresponding to the pixel group being processed.
- a process of determining the pixel positions for forming these dots from the number of large, medium, and small dots is performed (step S800). 6).
- the hierarchical matrix is a matrix indicating the easiness of dot formation for each pixel in the pixel group.
- FIG. 31 is an explanatory diagram conceptually showing how pixel positions forming large, medium, and small dots are determined with reference to an order matrix. For example, by decoding the count data,
- a pixel position at which a large dot is to be formed is determined.
- the number of large dots is one.
- a large dot is formed at a pixel whose order value is set to “ ⁇ ” in the order matrix.
- N the number of large dots
- a large dot is to be formed in a pixel for which the order value is set in the order matrix from “ ⁇ ” to “ ⁇ ”.
- pixel positions where large dots are formed are indicated by fine diagonal lines.
- the pixel position for forming the medium dot is determined. The number of medium dots is two, and a large dot is formed at the pixel position where the order value "1" is set, so the medium dot is the pixel position where the order value "2" is set and the order value Pixel position where "3" is set Formed with the device.
- pixel positions where medium dots are formed are indicated with a slightly rough diagonal line. Finally, the pixel position where a small dot is formed is determined. Since the number of small dots is one, a large dot is formed at the pixel position with an order value of “1” and a medium dot is formed at the pixel position with an order value of “2” and “3”. An order value “4” is formed at the set pixel position. In FIG. 31, pixel positions where small dots are formed are displayed with coarse hatching. In step S806 of FIG. 29, a process of determining a pixel position at which a dot is formed in the order of large dot, medium dot, and small dot is performed with reference to the order matrix.
- step S808 After decoding the coded number data for one pixel group and determining the pixel positions forming the large, medium, and small dots, it is determined whether or not the processing has been completed for all the pixel groups. Step 9 of step S808). If an unprocessed pixel group remains (step S808: n0), the process returns to step S800 and repeats a series of subsequent processes for the new pixel group. When it is determined that the pixel positions have been determined for all the pixel groups in this way (step S808: yes), the process exits the pixel position determination process of the second embodiment shown in FIG. 29 and returns to the image printing process. Then, various dots are formed on the printing paper. As a result, an image corresponding to the image data is printed.
- the encoded number data is decoded, it is decoded into data of the number of dots of various dots.
- the decoding may be performed to the total number of dots, medium dots, and small dots.
- the total of large dots and medium dots is three, and the large dot That is, the total of the middle, small, and small dots is four.
- FIG. 32 is an explanatory view conceptually showing a decoding table referred to for decoding the encoded number data in this way.
- the process of determining the pixel position can be speeded up as follows. For example, the case where the pixel position of the middle dot is determined in FIG. 31 is described. Since the total number of the large dot and the middle dot is decoded as three, the order value changes from “ ⁇ ” to “ Select up to 3 pixels. Then, it is determined that a medium dot is to be formed at the selected pixel, excluding pixels at which other dots (large dots) have already been formed.
- the order value of the pixels forming the medium dot differs depending on the number of large dots, and the order of the pixels forming the small dot The order value depends on the number of large and medium dots. For this reason, when determining the pixel positions for forming the medium dot and small dot, it is necessary to always select a pixel with an appropriate order value while considering the large dot or the number of large dots and medium dots. .
- a pixel having an appropriate order value can be selected without considering the number of large dots and medium dots, so that the process of determining a pixel position can be speeded up.
- the coded number data is immediately obtained by simply referring to the conversion table. Obtainable. Therefore, the coded quantity data Evening can be generated very quickly, and the processing content can be extremely simple. In this regard, while comparing with the case of generating piece data without using a conversion table,
- processing speed may be reduced by performing pipeline processing.
- coded number data when referring to the conversion table, coded number data can be obtained without any conditional branching as shown in Fig. 27, and therefore, the effect of the pipeline processing can be sufficiently achieved.
- the count data generation process of the second embodiment is not only a simple process, but can be said to be a process suitable for high-speed processing from such a point.
- the process of generating the coded count data is merely a process of referring to the conversion table, and is executed using a CPU without high data processing capability or a chip incorporating a dedicated logic circuit. It is also easy to do.
- FIG. 33 is an explanatory diagram showing the results of trial calculation of the data size of the conversion table under various conditions.
- the data size of the conversion table in the second embodiment is also determined by the number of classification numbers, the range of possible pixel group gradation values, and the per-number data. Determined by De Ichibancho.
- the number of classification numbers is determined by the size of the dither matrix and the size of the pixel group.
- the data length of the number data is determined by the number of states per pixel group, that is, the type of combination of the number of large, medium, and small dots that can occur in one pixel group. For example, as described above, one pixel group is composed of eight pixels, and one pixel is If there are four possible states: large dot formation, medium dot formation, small dot formation, and no dot formation, there are 1655 combinations of numbers of large, medium and small dots. I have. If there are 16 5 ways, it can be expressed if it has an 8-bit data length, so the data length per piece of data is 1 byte. Similarly, when one pixel group is composed of 16 pixels, a data length of 10 bits is required for each data item, so that the data length is 2 bytes.
- Figure 33 shows the results of trial calculation of the data amount of the conversion table for each combination of the size of the dither matrix and the size of the pixel group.
- the data length required for one piece of data is shown on the right side of FIG.
- the data amount of the conversion table in the second embodiment is also at most 1 M byte, and is actually 256 K bytes I ⁇ to 5 12 K bytes. It is considered to be in the order of bytes.
- the amount of data is small enough to fit in the cache memory of a general computer, and also to the memory of imaging devices such as digital cameras 120 and color printers 200. , And can be fully mounted.
- the data compression ratio is calculated as follows. For example, describing the case of the above-described embodiment, the number of pixels included in the pixel group is eight. Also, large dots, medium dots, small dots Since there are four states of formation and dot formation, a data length of 2 bits per pixel is required. Therefore, to express the type of dot formed for each pixel, a 16-bit data length is required for each pixel group.
- the data compression ratio is about 0.5, although it varies depending on the conditions. In other words, by encoding the combination of the number of large, medium, and small dots, the data amount can be reduced by almost half compared to the case of outputting the type of dot and the presence or absence of formation for each pixel. It can output to 200 quickly.
- FIG. 34 An example of the image output system according to the second embodiment of the present invention is shown in FIG. 34 as a printing system for printing an image.
- the configuration of each part in FIG. 34 is similar to the first mode described with reference to FIG. are doing.
- the printing system illustrated in FIG. 34 prints an image as follows. First, the computer OA divides an image into a plurality of pixel groups by grouping pixels constituting an image into a predetermined number of adjacent pixel groups. Then, for each pixel group, number data representing the number of dots formed in the pixel group is generated.
- the number data generation module provided in the OA converts the image into a The division is performed to generate number data for each pixel group.
- the generated quantity data is supplied from the quantity data supply module provided in the computer 1OA to the printer 20A.
- the dot formation presence / absence determination module provided in the printer 2 OA determines the presence / absence of dot formation for each pixel in the pixel group.
- the dot forming module prints an image by forming a dot on a print medium according to the presence or absence of the dot formation determined for each pixel.
- the number data for each pixel group can be a much smaller data amount. Therefore, computer ⁇ 0
- the printer 20A can receive the data very quickly; ⁇ possible It is. Further, upon receiving the number data, the printer 2 OA determines whether or not to form dots for each pixel included in the pixel group as follows. First, for each pixel in the pixel group, an order value indicating the order in which dots are formed in the pixel group is stored in the order value storage module. Further, the correspondence between the combination of the order value and the number data and the presence / absence of dot formation for the pixels having the order value is stored in the correspondence storage module in advance.
- the hardware configuration of the printing apparatus according to the third embodiment is the same as that of the first embodiment, and thus the description is omitted.
- An overall flow of the image printing process in the third embodiment is shown in a flowchart of FIG.
- the flowchart in FIG. 35 is almost the same as the processing in the first embodiment (FIG. 5), and the contents of the count data generation processing described as step S107 are different from those in the first embodiment.
- the difference is that a dot formation presence / absence determination process is performed in step S109 instead of the pixel position determination process in step S108. Therefore, when the processing is started, the computer 100 starts reading image data (step S100), and performs color conversion processing after reading the color image data (step S102). When the color conversion processing is completed, the resolution conversion processing is started (step S104).
- the computer 100 After converting the resolution to the print resolution, the computer 100 starts the count data generation process (step S107).
- the details of the count data generation process will be described later in detail (Fig. 36), and here only the outline will be described.
- the number data generation process one image is divided into a plurality of pixel groups by grouping adjacent pixels into a predetermined number of pixel groups. Then, data indicating the number of dots to be formed in each pixel group, that is, number data, is determined for each pixel group. In general, whether or not a dot is formed at a certain pixel depends on the image data of that pixel. Therefore, the number data representing the number of dots formed in the pixel group is also determined by the It can be determined based on image data.
- the number data determined for each pixel group is output to the color printer 200.
- the number data generation process the number data is generated for each pixel group based on the image data of each pixel in this manner, and then, The processing for supplying to the color printer 200 is performed.
- the CPU incorporated in the control circuit 260 of the color printer 200 receives the number data supplied from the computer 100, it starts a dot formation presence / absence determination process (step S109). Although detailed processing contents will be described later, the following processing is roughly performed in the dot formation presence / absence determination processing.
- the number data supplied from the convenience store 100 is data representing the number of dots to be formed in the pixel group, and the number of dots is formed in any pixel in the pixel group. It is uncertain if they will.
- a process of forming a dot on an output medium is performed according to the determined presence or absence of dot formation.
- Step S110 The actual dot formation has already been described, and will not be described.
- the data of the number of dots to be formed in the pixel group is supplied from the computer 100 to the printer 200, and the data is supplied to the pixel group. It does not supply data on the presence or absence of dot formation for each pixel included.
- the number of dots to be formed in a pixel group can be represented by a much smaller data amount than data representing the presence or absence of dot formation for each pixel.
- the computer 100 Data can be supplied very quickly to the network 200.
- the number of dots formed in the pixel group can be represented by a much smaller data amount than the data indicating the presence or absence of dot formation for each pixel.
- the color printing is performed from the computer 100. Data can be supplied to the printer 200 very quickly.
- the color printer 200 determines whether or not to form dots for each pixel in the pixel group using a method described later. This makes it possible to make decisions very quickly.
- the image quality does not deteriorate even if only the data of the number of dots is supplied.
- FIG. 36 is a flowchart showing the flow of the count data generation process of the third embodiment.
- a pixel group is generated by grouping a predetermined number of pixels (step S200a).
- a total of eight pixels, four pixels in the main scanning direction and two pixels in the sub-scanning direction, are grouped into a pixel group.
- one pixel of interest (pixel of interest) to be processed is set from among a plurality of pixels that have been put together as a pixel group (step S202a). Then, by comparing the tone value of the image data assigned to the pixel of interest with the threshold value of the dither matrix, the presence or absence of dot formation for the pixel of interest is determined (step S204a). That is, as shown in FIG.
- Step S206a it is determined whether or not the above processing has been performed on the selected pixels in the pixel group (step S206a), and if unprocessed pixels remain in the pixel group (step S206).
- Step S202a: no a series of processes following Step S202a are performed.
- step S208a the number of pixels for the processed pixel group is generated (step S208a).
- the number of dots formed in the pixel group is counted, and the obtained number of dots is used as number data.
- step S210a when the processing for one pixel group is completed, it is determined whether or not the processing has been completed for all pixels of the image (step S210a), and if unprocessed pixels remain, Return to step S200a to generate a new pixel group, A series of processing is performed to generate the number data of the pixel group (step S208a). By repeating such processing, when the processing for all the pixels in the image is completed (step S210a: yes), the number data obtained for each pixel group is sent to the color printer 200. (Step S212a), and the number data generation process shown in FIG. 36 ends. As a result, the number data for each pixel group is supplied to the color printer 200.
- step S109 in FIG. 35 a process for determining the presence or absence of dot formation for each pixel in the pixel group based on the number data supplied from the computer # 00 will be described.
- FIG. 37 is a flowchart showing the flow of the dot formation presence / absence determination processing of the third embodiment. This process is a process executed by a CPU built in the control circuit 260 of the color printer 200.
- FIGS. 38a, 38b, and 38c are explanatory diagrams conceptually showing how the presence or absence of dot formation is determined for each pixel in the dot formation presence / absence determination processing. In the following, with reference to FIGS. 38A to 38C, the contents of the dot formation presence / absence determination processing according to the third embodiment will be described in accordance with the flowchart shown in FIG.
- step S300a When the dot on / off state determination process is started, first, one pixel group is selected (step S300a), and the number data of the pixel group is obtained (step S302a). Here, it is assumed that the number data as shown in FIG. 38A has been supplied.
- step S304a Next, one target pixel is selected from the pixels included in the selected pixel group (step S304a), and a value (order) indicating the order in which dots are formed in the target pixel in the pixel group is selected. Value) (step S306a).
- the order value of the target pixel is It can be easily obtained by referring to a preset order value matrix as shown in 38b. In the order value matrix illustrated in FIG.
- an order value is set in advance for the pixel position of each pixel constituting the pixel group.
- the order value “1” is set for the pixel at the upper left corner in the pixel group
- the order value “6” is set for the pixel to the right of that pixel.
- the order value set at the position of the target pixel is acquired with reference to such an order value matrix.
- only one set of order value matrices is stored. A plurality of matrices may be stored, and the order value of the target pixel may be acquired while switching the order value matrix for each pixel group.
- FIG. 39 is an explanatory diagram conceptually showing a conversion template referred to in determining whether or not a dot is formed for a target pixel.
- the presence or absence of dot formation is set in the conversion table in association with the combination of the order value and the number data.
- the order value takes a value from ⁇ to 8
- the order number takes a value from 0 to 8. Therefore, in the conversion table, values indicating whether or not to form dots are set in association with the 72 combinations of these combinations.
- “1” is set for a combination that forms a dot
- “0” is set for a combination that does not form a dot.
- the order value is “1 J” and the count data is It is “3” as shown in a.
- the order value “1 J” The value set for the combination of the number data “3 J” is “1 J, that is, it can be determined that a dot is to be formed for this pixel.
- step S 30 in FIG. In 8a by referring to the conversion table, the presence or absence of dot formation for the target pixel is immediately determined from the count data for the pixel group and the order value of the target pixel.
- step S310a After determining the presence or absence of dot formation for one pixel, it is determined whether or not the presence or absence of dot formation has been determined for all pixels in the selected pixel group (step S310a). If there are still pixels for which the presence or absence of dot formation has not yet been determined (step S310a: n0), the process returns to step S304a and a new pixel is selected from the pixel group. As a target pixel This process is repeated, and if it is determined that dot formation has been determined for all pixels in the pixel group (step S310a: yes), then the number data is counted.
- step S312a It is determined whether or not the processing has been completed for all the supplied pixel groups (step S312a), and if an unprocessed pixel group remains (step S312a: n0) Returning to step S300a, a new pixel group is selected, and a series of subsequent processing is performed.By repeating such processing, the number of data supplied from the computer is reduced to dot formation for each pixel.
- step S306a yes
- the dot formation presence / absence determination processing of the third embodiment when the number data of the pixel group is received, the order value of the target pixel is obtained by referring to the order value matrix, and the obtained order value and number data are obtained.
- the process of determining the presence or absence of dot formation only refers to stored data, it can be easily executed in hardware using a chip incorporating a dedicated logic circuit. If the processing for determining the presence or absence of dot formation is performed in hardware, processing can be performed at even higher speed, and an image can be printed more quickly.
- the effect of increasing the processing speed in recent computers employing fewer pipelines and employing pipeline processing can be obtained.
- the above-described dot formation presence / absence determination processing of the third embodiment includes various elements that enable quick processing. Therefore, under any conditions, the number data is printed for each pixel. It can be quickly converted to data indicating the presence or absence of formation, and in turn, images can be printed quickly.
- one or more sets of order value matrices are set in advance, and the same order value matrix is always referred to or referred to.
- the description has been made assuming that the presence or absence of dot formation for each pixel is determined while randomly switching the order value matrix.
- the order value matrix is generated based on the dither matrix, and the position of the pixel group is determined. In response By determining the presence or absence of dot formation with reference to the appropriate order value matrix, it is possible to determine the presence or absence of dot formation more appropriately, and thus to print high-quality images. .
- FIG. 40 is a flowchart showing the flow of a dot formation presence / absence determination process according to a modification.
- the process is the same as the process shown in FIG. 37 except for step S330a. That is, in this modification, after obtaining the number data of the selected pixel group (step S302a), the order corresponding to the selected pixel group is selected from the order value matrix stored in a plurality of sets. The value matrix is read (step S330a).
- step S330a Such processing will be described in detail with reference to FIGS. 41a to 41d and FIGS. 42a to 42d.
- FIG. 41 a to 41 d are explanatory diagrams showing a method of generating a plurality of order value matrices referred to in the dot formation presence / absence determination processing of the modified example.
- one pixel group is assumed to be composed of a total of eight pixels, four pixels in the main scanning direction and two pixels in the sub-scanning direction.
- the threshold of tricks the threshold of 4 pixels in the main scanning direction and 2 pixels in the sub-scanning direction, a total of 8 pixels each, is collected into a block.
- FIG. 41a is an explanatory diagram conceptually showing a state in which threshold values for eight pixels at the upper left corner of the dither matrix are grouped into blocks.
- FIG. 41a is an explanatory diagram conceptually showing a state in which threshold values for eight pixels at the upper left corner of the dither matrix are grouped into blocks.
- the dither matrix has a size of 128 pixels in the main scanning direction and 64 pixels in the sub-scanning direction. If pixels of 4 pixels in the main scanning direction and 2 pixels in the sub-scanning direction are grouped into blocks, the dither matrix will be 32 blocks each in the main scanning direction and the sub-scanning direction, and a total of 10 2 4 Will be divided into blocks. These blocks are numbered serially from number 1 to number 124, as shown in Figure 4 lb. Then, one set of ordinal values matrix is generated from each block from No. 1 to No. 104.
- FIG. 41c is an explanatory diagram showing a state in which an order value matrix is generated from the block having the serial number 1. In the left half of Fig.
- the threshold of the dither matrix included in the block with the serial number 1 is shown.
- the tone value of the image data is compared with the threshold value of the dither matrix, and it is determined that a dot is formed when the image data is larger. Therefore, a pixel having a smaller threshold value of the dither matrix is more likely to form a dot. Therefore, the pixel in which the first dot is formed in the first block shown in FIG. 41C can be considered as a pixel for which the threshold value “1” is set. Therefore, “1” is set to this pixel as the order value.
- the pixel in which the second dot is formed can be considered as a pixel for which the threshold value “4 2”, which is the second smallest threshold value, is set. Therefore, the order value “2” is set for this pixel.
- the serial number 1 shown in the right half of FIG. The order value matrix of incense can be obtained.
- Fig. 4 1d shows the order value matrix of serial number 2 by setting the order value "1" to the order value "8” in order from the pixel for which the small threshold is set in the block. Is generated.
- FIGS. 42 a to 42 d are explanatory diagrams showing a method of selecting an order value matrix corresponding to a pixel group. Now, as shown in Fig.
- the pixel group for which dot on-off state is to be determined is the n-th pixel group in the main scanning direction and m in the sub-scanning direction based on the upper left corner of the image. It is assumed that it is at the position of the pixel group.
- the position of such a pixel group is represented by a coordinate value (n, m).
- the size of the dither matrix is not usually as large as the image. For this reason, the dithering method uses one dither matrix repeatedly while shifting its position slightly with respect to the image. For the same reason, one dither matrix is repeatedly used while being moved little by little in the process of determining whether or not to form a dot as shown in FIG.
- Fig. 42b conceptually shows how the dither matrix is used repeatedly while gradually moving it in the main scanning direction.
- the size of the block that divides the dither matrix is the same as the size of the pixel group that generated the number data, so the dither matrix was moved as shown in Fig. 42b.
- each block of the dither matrix matches the position of the pixel group. In other words, any block that divides the dither matrix is applied to all pixel groups.
- one dither matrix includes 32 blocks in each of the main scanning direction and the sub-scanning direction, and the coordinates of a pixel group to be processed. Values are (n, m),
- N and M can be obtained by the following equations.
- N n ⁇ i n t (n / 32) X 32
- int is an operator indicating that the value after the decimal point is truncated to be converted into an integer. That is, int (n / 32) represents an integer value obtained by truncating the number after the decimal point in the calculation result of nZ32. Therefore, when determining the presence or absence of dot formation for a certain pixel group, N and M are obtained from the coordinate values (n, m) of the pixel group by the above equation, and then the pixels are located at the corresponding positions in the dither matrix. It is sufficient to obtain the serial number of the block and use the order value matrix generated from the block. However, in practice, the values of M and N can be obtained very easily without performing the calculations shown in Fig. 42d.
- FIG. 43 is an explanatory diagram specifically showing a method of selecting an applicable order value matrix from the coordinate values (n, m) of the pixel group.
- the symbol (a) in FIG. 43 conceptually shows 10-bit binary data representing the numerical value n.
- serial numbers from 1 to 10 are assigned from the most significant bit to the least significant bit.
- int nZ32
- I will.
- the binary data of int (n / 32) can be obtained by simply shifting the binary data of the numerical value n shown in code (a) in Fig. 43 by 5 bits to the right. Obtainable.
- FIG. 43 (c) conceptually shows ⁇ n t (n / 3 2) ⁇ 32 binary data obtained by bit-shifting the numerical value n. Then, by subtracting .int (n / 32) X 32 from the numerical value n, the aforementioned numerical value N can be obtained.
- the binary number of the number n see (a) in Figure 43) and i n t
- Step S of the dot formation existence determination process shown in FIG. 43 the case where the numerical value N indicating the block position in the dither matrix is obtained from the numerical value n of the coordinate value (n, m) of the pixel group has been described. Therefore, the numerical value indicating the block position can be obtained very easily from the numerical value m. After all, if the coordinate values (n, m) of the pixel group are given, the numerical values N, M are obtained from the numerical values n, m. Thus, it is possible to know what sequence number matrix the serial number is applied to the pixel group. Step S of the dot formation existence determination process shown in FIG.
- Step S304a After reading the order value matrix corresponding to the pixel group as described above, From the pixel group, one target pixel for which dot formation is to be determined is selected (step S304a), and the order value of the target pixel is obtained with reference to the order value matrix below. (Step S306a), refer to the conversion table.
- Step S308a The process of determining whether or not a dot is formed for the target pixel (Step S308a) is repeated until all the pixels in the pixel group and all the pixel groups are completed. Is completed (step S312a: yes), the dot formation presence / absence determination processing of the modification shown in Fig.
- a plurality of order value matrices are generated based on the dither matrix, and the presence or absence of dot formation for a certain pixel group is determined by the dither method. Is applied, the presence or absence of dot formation is determined using the order value matrix generated from the dither matrix of the portion applied to the position of the pixel group. It is possible to determine the presence or absence of dot formation so that a distribution similar to the distribution of dots obtained by using a dot is obtained.
- the threshold is set with an appropriate distribution so that it can be formed, a high-quality image can be printed if the distribution according to the dot distribution by the dither matrix is obtained. Furthermore, if the dither matrix used to generate the order value matrix and the dither matrix used in the count data generation processing shown in FIG. 36 are the same matrix, the first embodiment will be described. As described above (see Figs. 8a to 8d and 9a to 9d), the dot distribution reconstructed from the count data almost always has a dot formation for each pixel using the dither method. The dot distribution is exactly the same as when the presence or absence is determined.
- the dot distribution will be different, but in the image data, the approximation between adjacent pixels will be similar. In many cases, the dot distribution will be the same, since they tend to have (or have the same) tone values. Therefore, the presence or absence of dot formation can be determined so as to obtain an appropriate dot distribution, and a high-quality image can be printed accordingly.
- the memory capacity required to store the conversion template will be described. As shown in Fig. 39, whether or not dots are formed is set in the conversion table for each combination of the order value and the number data, so the data size of the conversion table can take the order value and the number data, respectively. It is determined by the number and the data length required to indicate the presence or absence of dot formation for one pixel. Since the order value indicates the order in which dots are formed at each pixel in the pixel group, the order value is included in one pixel group. It can take the same type of value as the number of pixels.
- the number data represents the number of dots that can be formed in the pixel group, it can take a value from 0 to the number of pixels, and therefore can take the value of the number of pixels + 1 value. Further, here, it is assumed that one pixel only takes a state of whether a dot is formed or not, so that the presence or absence of dot formation for one pixel can be expressed by one bit. After all, the memory capacity for storing the conversion table is n, where n is the number of pixels included in the pixel group.
- the amount of memory for storing the order value matrix is determined by the amount of memory required for each matrix and the number of matrixes.
- the order value matrix the order in which dots are formed at each pixel in the pixel group is set, so the amount of memory per matrix is determined by the number of pixels included in the pixel group.
- the number of order value matrices is equal to the number of blocks obtained when the dither matrix is divided by blocks of the same size as the pixel group, as described above with reference to FIGS. 41a to 41d.
- FIG. 44 is an explanatory diagram showing the results of a trial calculation of the amount of memory required to store the order value matrix, assuming a dither matrix of various sizes and a pixel group of various sizes.
- the size of the dither matrix is 64 ⁇ 64 (ie, 64 pixels in the main scanning direction and 64 pixels in the sub-scanning direction), and 128 ⁇ 64 (128 pixels in the main scanning direction, 64 pixels in the sub-scanning direction), and 128 x 128 (128 pixels in the main scanning direction, 128 pixels in the sub-scanning direction) Is assumed.
- the pixel group sizes are 2 X 2 (2 pixels in the main scanning direction, 2 pixels in the sub-scanning direction), 4 X 2 (4 pixels in the main scanning direction, 2 pixels in the sub-scanning direction), 4 X 4 ( Three types of sizes are assumed: 4 pixels in the main scanning direction and 4 pixels in the sub-scanning direction.
- the trial calculation result is shown in FIG. Is shown.
- the number of order value matrices is the number of blocks obtained by dividing the dither matrix by the same size as the pixel group, so the number of pixels of the dither matrix (1 2 8 X 6 4) per pixel group Dividing by the number of pixels of (4 X 2) gives 10 24.
- the ordinal value set in the ordinal value matrix takes eight values from 1 to 8, so what is one ordinal value? If it is a bit, it can be expressed.
- Figure 44 summarizes the results of a trial calculation of the amount of memory required to store all order value matrices under various conditions. As is clear from the results of the trial calculation shown in the figure, it is considered that at most 10 Kbytes of memory is required to store the order value matrix. For this reason, the amount of memory required to store the conversion table and the order value matrix does not become so large as to be a hindrance to mounting it in an actual product.
- the dot that can be formed by the color printer 200 is one type.
- printers capable of forming various types of dots such as dots of different sizes and dots of different ink densities (so-called multi-valued dot printers), are widely used to improve print quality. Have been.
- the invention of the present application can provide a great effect even when applied to such a multi-valued dot printer.
- a fourth embodiment a case will be described in which the present invention is applied to a multilevel dot printing system.
- the flowchart of the image printing process of the fourth embodiment is the same as the image printing process of the first embodiment shown in FIG. 35.
- the outline of the image printing process of the fourth embodiment will be briefly described with reference to the flowchart of FIG.
- the image printing process of the fourth embodiment is started, first, the image data is read by the computer 00, and then the color conversion process is performed (steps S100 and S102 in FIG. 35). Equivalent). Next, a resolution conversion process is performed to solve the image data. After converting the image resolution into the printing resolution (equivalent to step S104), the number data generation process is started (equivalent to step S106).
- the color printer 200 can form only one type of dot, and in the number data generation process, the number representing the number of dots formed in the pixel group is used. The data was generated and output to a color printer 200.
- the color printer 200 can form a plurality of types of dots.
- count data is generated, which indicates how many large dots, medium dots, and small dots are formed in each pixel group. Will be done.
- the number of large dots, medium dots, and small dots is not output as it is, but output in a coded state. . Details of the number data generation processing of the second embodiment will be described later.
- the dots that can be formed by the color printer 200 are described as large dots, medium dots, and small dots, which are dots having different sizes, but of course, the types of dots are different. Is not limited to the case of different sizes. For example, when a plurality of types of dots having different densities of the ink forming the dots are used, or when one dot is formed in a simulated manner by forming a plurality of fine dots, the density of the fine dot is determined.
- the CPU built in the control circuit 260 of the color printer 200 receives the number data supplied from the computer 100, the CPU starts the dot formation presence / absence determination processing. (Equivalent to step SI08 in Fig. 35).
- the dot formation presence / absence determination processing of the fourth embodiment when the coded number data is received, a large dot, a medium dot, and a small dot are obtained for each pixel in the pixel group. A process is performed to determine which dot is to be formed or whether no dot is formed.
- various dots are formed according to the obtained results (corresponding to step SI10 in FIG. 35).
- an image corresponding to the image data is printed.
- FIG. 45 is a flowchart showing the flow of a process for determining the number of large dots, medium dots, and small dots to be formed in a pixel group and generating the number of dots. It has already been described that the details of such processing are disclosed in Japanese Patent No. 3292210. Hereinafter, description will be given according to the flowchart.
- a predetermined number of adjacent pixels are put together to form a pixel group (step S500a).
- a total of eight pixels that is, four pixels in the main scanning direction and two pixels in the sub-scanning direction, are collected as a pixel group.
- one pixel to be processed is selected (step S502a), and a large dot, medium dot is selected for the selected processed pixel.
- step S504a it is determined whether small dots are formed. Onaka Judgment of the presence or absence of the formation of small dots means that a multi-tone image is eventually converted to a low number of gradations by a combination of large, medium and small dots, which is a half in a broad sense.
- step S506a It is determined whether the processing has been completed for all the pixels in the pixel group while determining whether to form any of the small dots or not to form any of the dots. ), If it has been completed (step S506a: yes), the number of large dots, medium dots, and small dots formed in the pixel group is obtained (step S508a). As described above, when the number of various dots formed in the S element group is obtained, a combination of the numbers of the various types of dots (for example, a combination of one large dot, two medium dots, and one small dot) ) Is performed (step S51Oa). This is due to the following reasons.
- the number of dots must be output three times for one pixel group.
- the combination of the number of each dot is converted into an individual code set for each combination.
- the process of coding the combination of the large, medium, and small dots has already been described in the first embodiment (see FIG. 26), and a description thereof will be omitted.
- step S500a If unprocessed pixels remain, the process returns to step S500a and repeats a series of subsequent processes. When it is determined that processing has been completed for all pixels of the image, the coded number data is deleted. The output is performed (step S5 14a), and the count data generation process shown in FIG. 45 ends.
- the coded number data generated for each pixel group is received, and the presence or absence of dot formation is determined for each pixel in the pixel group.
- the processing will be described.
- the presence / absence of dot formation is immediately determined from the count data and the order value by referring to the conversion table.
- the conversion table it is possible to immediately determine the presence or absence of the formation of small and medium-sized dots from the coded number data and the order value.
- the dot data from the number data is used without using a conversion table.
- a process for determining whether or not a mouse is formed will be described.
- a dot formation presence / absence determination process of the fourth embodiment will be described in which the presence / absence of various large / medium / small dots can be quickly determined from the number data by referring to the conversion table.
- FIG. 46 is a flowchart showing the flow of processing for determining whether or not various large, medium, and small dots are formed without referring to the conversion table.
- the following is a brief description according to the flowchart.
- each pixel in the pixel group is roughly referred to with reference to the read order value matrix.
- the order value matrix is a matrix that sets the order in which dots are formed for each pixel in the pixel group, as described above with reference to FIGS. 41a to 41d. The manner in which the presence or absence of formation of various large, medium, and small dots is determined for each pixel with reference to the order value matrix has already been described with reference to FIG.
- a pixel that forms a large dot is determined (step S608a in FIG. 46).
- the number of large dots is one, the pixel where the dot is most likely to be formed, that is, the pixel whose order value is set to ⁇ 1 ”in the order value matrix is large.
- N it is determined that a large dot is to be formed in a pixel for which the order value is set to a value from “1 J to“ N ”in the order value matrix.
- pixels forming large dots are displayed with fine diagonal lines.
- the pixels for forming the large dots are determined from the pixels in which no large dots are formed (step S 6 ⁇ O a). From the pixels in which neither a large dot nor a medium dot is formed, the pixel that forms a small dot is determined (step S612a), and finally, a large dot, a medium dot, and a small dot are formed. It is determined that a dot is not formed for a pixel that has not been subjected to the process (step S614a).
- step S it is determined whether or not the processing has been completed for all the pixel groups (step S). 6 16 a). If an unprocessed pixel group remains (step S616 &: ⁇ 0), the process returns to step 3600a and repeats a series of processes for a new pixel group. When it is determined that the processing has been completed for all the pixel groups in this way (step S616a: yes), the dot formation determination processing shown in FIG. 46 ends.
- the coded number data when the coded number data is received, it is decoded into data indicating the number of large / medium / small dots to be formed in the pixel group, and then any dot is determined for each pixel. It is a two-step process of deciding whether to form a bird. However, by referring to the conversion table, the dots to be formed in each pixel can be immediately determined without decoding the number data.
- a dot formation presence / absence determination processing for determining whether or not a dot is to be formed with reference to a conversion table will be described.
- This dot formation presence / absence determination processing is different from the dot formation presence / absence determination processing of the modified example described with reference to FIG. 40 in the third embodiment described above only in the conversion table to be referred to.
- the processing flow is the same. Therefore, in the following, while diverting the flow chart of FIG. 40, a dot formation presence / absence determination as a modification of the fourth embodiment will be described.
- the dot formation presence / absence determination processing is started, first, one pixel group is selected, and the number data of the pixel group is obtained (corresponding to steps S300a and S302a). ). Next, an order value matrix corresponding to the selected pixel group is read from the order value matrix stored in a plurality of sets (corresponding to step S330a).
- n and m are obtained from the coordinates (n, m) of the pixel group. Extract bits and find N and M, respectively. Then, select and read the order value matrix generated from the N rows and M columns block in the dither matrix. After reading the order value matrix corresponding to the pixel group as described above, select one target pixel from which the dot formation is to be determined from the pixel group being processed (step S3). 0 4a).
- the order value of the target pixel is obtained by referring to the read order value matrix (equivalent to step S306a), and then the dot formation for the target pixel is performed by referring to the conversion table. Is determined (equivalent to step S308a).
- data indicating the presence or absence of dot formation is set for each combination of the number data and the order value ( See Figure 39).
- the conversion table referred to in the dot formation presence / absence determination processing of this modification large, medium, and small dots are formed for each combination of the number of encoded states and the order value. Or data indicating whether a dot is not formed.
- the presence or absence of dot formation can be immediately determined.
- the dot formation presence / absence determination processing of the second embodiment by referring to such a conversion table, it is immediately determined whether a large, medium, or small dot is formed in the target pixel, or whether a dot is not formed. (Equivalent to step S308a in FIG. 40).
- the presence / absence of dot formation is determined with reference to a conversion table as shown in FIG. 47, the presence / absence of dot formation for large / medium / small dots is appropriately determined. The reason will be described.
- the third embodiment as described above with reference to FIGS.
- a two-step operation when determining whether or not to form dots without referring to the conversion template, a two-step operation is roughly performed. Has passed. That is, first, in the first stage, the coded number data is converted into the number of large, medium, and small dots. In the subsequent second step, the presence or absence of dot formation for each pixel is determined according to the order value matrix.
- the coded number data and the combination of the numbers of the large, medium, and small dots have a one-to-one relationship. In other words, if one coded number data is given, the combination of the numbers for various dots can be uniquely determined.
- the presence or absence of dot formation for each pixel is determined according to the order value matrix. That is, if the order value matrix is determined, there is a one-to-one relationship between the combination of the numbers of various dots and the presence or absence of dot formation for each pixel. As described above, the combination of the numbers for each type of dot is uniquely determined from the coded number data. Therefore, if the ordinal value matrix is determined, the number combination is determined from the coded number data. For each pixel in the pixel group, the presence or absence of the formation of various dots is uniquely determined.
- the order value and the type of the dot formed in the pixel having the order value are determined in advance for all the number data, and are converted into the conversion table as shown in FIG. 47. Set it. Then, when determining the presence or absence of dot formation for the target pixel in the pixel group, the order value of the target pixel is obtained by referring to the order value matrix, and then the order value is obtained by referring to the conversion table.
- step S310a in FIG. 40 If there are still pixels for which the presence or absence of dot formation has not been determined, the process returns to the portion corresponding to step S304a, a new target pixel is selected, and a series of subsequent processes are performed.
- step S312a the count data It is determined whether or not the processing has been completed for all the pixel groups supplied with (step S312a). If an unprocessed pixel group remains, the process returns to the beginning, selects a new pixel group, and performs a series of subsequent processing. Such processing is repeated, and when the processing is completed for all the pixel groups, the dot formation presence / absence determination processing of this modified example is completed.
- the dot formation presence / absence determination processing of the fourth embodiment including the modified example described above when the coded number data is received, the order value of the target pixel is obtained by referring to the order value matrix.
- the main processing content of the dot on / off state determination processing in these embodiments is very simple processing in which data is read out with reference to the order value matrix and the conversion table. Therefore, even with a color printer 200 that does not have a high data processing capability like the computer 100, it can be executed sufficiently quickly, and the image can be printed quickly accordingly. Become.
- the dot on / off state determination processing of the fourth embodiment it is possible to determine whether or not a dot is formed on the target pixel simply by referring to the matrix or the sample, and the conditional branch is included in the processing. As described above, the speed of processing by a CPU with a specific pipeline structure etc. will be faster. As described above, in the dot formation presence / absence determination processing (including the modified example) of the fourth embodiment, the dot formation presence / absence for each pixel in the pixel group is determined easily and quickly. Although it is possible to specify them, it is necessary to store a large number of order value matrices and a conversion table as shown in Fig. 47.
- the amount of memory required to store the conversion table and the order value matrix is also included in the product in the dot formation existence determination process of the fourth embodiment, as in the third embodiment described above. It will not be so large as to be an obstacle to doing so.
- the order value matrix is the same as in the third embodiment described above. In other words, the amount of memory for storing the order value matrix is determined by the size of the dither matrix and the size of the pixel group. As shown in Fig. 44, about 10 Kbytes of memory is used. If there is enough, it will be possible to store enough. Next, the memory capacity required for storing the conversion table will be described. As shown in FIG.
- the conversion table can be sufficiently stored if it is several kilobytes. Therefore, in the dot formation presence / absence determination processing of the fourth embodiment, the order value matrix and the conversion Only a small amount of memory is needed to store the table, and the memory capacity does not hinder the product from being installed.
- FIG. 49 is an explanatory diagram illustrating a third embodiment of the present invention, taking a printing system as an example.
- the printing system includes a computer 10B as an image processing device, a printer 20B as an image output device, and the like.
- a predetermined program is loaded on the computer 10B and executed, the printing system is executed.
- the fact that the computer 10B and the printer 20B function as an integrated image output system as a whole is the same as in the second embodiment.
- the printing system illustrated in FIG. 49 prints an image as follows.
- the computer 10B divides an image into a plurality of pixel groups by grouping pixels constituting the image into a predetermined number of adjacent pixels. Then, for each pixel group, number data representing the number of dots to be formed in the pixel group is generated and supplied to the printer 20B. The number data supplied to the printer 20B is converted by the dot formation presence / absence determination module into data representing the presence / absence of dot formation for each pixel in the pixel group. Next, an image is printed by the dot formation module forming a dot on a print medium according to the presence or absence of the dot formation determined for each pixel.
- the number data for each pixel group can be a much smaller data amount. Therefore, instead of supplying data representing whether dots are formed or not for each pixel from the computer 10B to the printer 20B. Instead, if the number data for each pixel is supplied, the data can be transferred very quickly.
- the pixel group number data is generated in the computer 10B as follows. First, in a pixel group tone value determination module, pixel group tone values are determined for a plurality of pixel groups that divide an image.
- the pixel group gradation value is a gradation value representing the pixel group, and is determined based on image data of each pixel included in the pixel group.
- the first correspondence relationship storage module stores the correspondence relationship between the combination of the classification number assigned to the pixel group and the pixel group gradation value and the number data of the pixel group having the combination. It is stored as Here, the classification number of the pixel group can be set by classifying each pixel group into a plurality of types according to the position in the image, or when the image is always divided in the same manner. Can be assigned an appropriate classification number in advance for each pixel group. Furthermore, it is possible to easily assign a classification number to a random number by using a random number or the like.
- the number data supply module determines the number data for each pixel group based on the classification number of each pixel group and the pixel group gradation value while referring to such a first correspondence. To the printer 20B.
- the pixel group gradation value of the pixel group can be easily obtained. Also, when a classification number is assigned to each pixel group, the classification number of each pixel group can be easily determined and assigned. Further, referring to the stored first correspondence, the number data can be easily obtained from the classification number and the pixel group gradation value. Therefore, in the printing system shown in FIG. 49, the number data for each pixel group can be generated extremely quickly, and the generated number data can be supplied to the printer 20B very quickly. it can. Further, the printer 2 OB determines whether or not to form a dot for each pixel in the pixel group based on the supplied number data in the following manner.
- an order value indicating the order in which dots are formed in the pixel group is stored in the order value storage module. Further, the correspondence between the combination of the order value and the number data and the presence / absence of dot formation for the pixel having the order value is stored in the second correspondence storage module as a second correspondence. Then, when the count data is received for each pixel group, the order value of each pixel in the pixel group is obtained, and the second correspondence is referred to for each combination of the count data and the order value, thereby obtaining Determines the presence or absence of dot formation for pixels.
- the computer 10B supplies the number data to the printer 20B;
- the number data since the number data is generated with reference to the stored first correspondence relationship, the number data can be generated quickly and easily.
- the received number data is converted into data indicating the presence or absence of dot formation for each pixel while referring to the second correspondence, so that the number data can be converted quickly and easily.
- the third embodiment of the present invention includes the image processing device (computer 10 B) in the first embodiment and the image output device (printer in the second embodiment) 20 B) Can.
- the fifth and sixth embodiments will be described in detail using such a printing system as an example.
- the computer 100 and the color printer 200 perform image processing (image printing processing) internally performed by the computer 100 and the color printer 200, respectively, in the third embodiment (FIG. 35). ) And its big flow are the same, so the explanation is omitted.
- FIG. 50 is a flowchart showing the flow of the count data generation process in the fifth embodiment.
- the count data generation process is performed by the combination printer 100.
- the count data generation process can be an extremely simple process. Alternatively, it can be implemented inside a digital camera 120 or the like.
- This number data generation process is the same as that described in the first embodiment, which is one of the first aspects of the invention (see FIG. 10), except for step S 204, so that step S 204 Instead of step S 205, the processing will be briefly described below with reference to a flowchart.
- the number data generation process of the fifth embodiment When the number data generation process of the fifth embodiment is started, first, a predetermined number of pixels adjacent to each other are grouped to generate a pixel group (step S200), and the classification number of the pixel group and the pixel group gradation The value is determined (step S202). The determination of the pixel group classification number and the pixel group gradation value has already been described in the first embodiment. Pixel group classification number and pixel group floor After the adjustment value is determined, the number data is determined by referring to the first conversion table (step S205). This first conversion table is the same table as the conversion table shown in FIG. 14 in the first embodiment. As described above, in this table, appropriate number data is stored in advance in association with the combination of the pixel group classification number and the pixel group gradation value. As described above, once the pixel group classification number and the pixel group gradation value are determined, the number data can be immediately obtained by referring to the first conversion table.
- step S206 it is determined whether or not the processing has been completed for all the pixels of the image data (step S206), and if unprocessed pixels remain (step S2). 06: no), returning to step S200, generating a new pixel group, and repeating a series of subsequent processes. These operations are repeated, and if it is determined that the processing has been completed for all pixels (step S206: yes), the number data obtained for each pixel group is output to the color printer 200 (step S206). S208), the count data generation process of the fifth embodiment shown in FIG. 50 is completed.
- FIG. 51 is a flowchart showing the flow of the dot formation presence / absence determination processing of the fifth embodiment.
- This process is a process executed by the CPU incorporated in the control circuit 260 of the power printer 200.
- This process is the same as the process of determining the presence or absence of dot formation (FIG. 37) in the third embodiment described as one of the second aspects of the present invention except for step S3008a.
- step S309a in place of step S308a in step 7.
- step S300a When the dot formation presence / absence determination processing is started, first, one pixel group is selected (step S300a), and the number data of the pixel group is obtained (step S302a). Next, one target pixel is selected from the pixels included in the selected pixel group.
- Step S304a a value (order value) indicating the order in which dots are formed at the target pixel in the pixel group is obtained (Step S304a).
- the order value of the target pixel can be easily obtained by referring to a preset order value matrix as shown in FIG. 38B.
- the presence or absence of dot formation for the target pixel is determined by referring to the second conversion table (step S309a).
- the second conversion table referred to to determine the presence or absence of dot formation for the target pixel is the same as that used in the third embodiment (see FIG. 39). While the first conversion table described above stores the number data in association with the combination of the classification number and the pixel group gradation value (see FIG. 14), the second conversion table stores the number data. As shown in FIG. 39, the presence or absence of dot formation is set in association with the combination of the order value and the number data.
- the second conversion table contains A value indicating the presence or absence of dot formation is set in association with the 72 combinations obtained by combining these.
- the order value is "1" as shown in Fig. 38b, and the count data is shown in Fig. 38a. As shown, it is "3".
- the value set for the combination of the order value “1” and the count data “3” is “1”, that is, the dot is set for this pixel. Can be determined to form.
- step S309a in FIG. 51 by referring to the second conversion table, the dot formation for the target pixel is performed from the number data of the pixel group and the order value of the target pixel. The decision is immediately made.
- step S31O After determining the presence or absence of dot formation for one pixel selected as the target pixel in this way, it is determined whether the presence or absence of dot formation has been determined for all pixels in the selected pixel group (step S31O). a). If there are still pixels in the pixel group for which dot formation has not yet been determined (step S310a: n0), the process returns to step S304a, and the process returns to step S304. A new pixel is selected as a target pixel, and the subsequent series of processing is performed. When such processing is repeated and it is determined that dot formation is determined for all pixels in the pixel group (step S310a: yes), then processing is performed for all pixel groups to which the number data is supplied. It is determined whether or not has been completed (step S312a).
- step S312a n0
- the process returns to step S300a to select a new pixel group and perform a series of subsequent processes.
- the number data supplied from the computer is converted into data indicating the presence or absence of dot formation for each pixel.
- step S306a yes
- the process for determining whether or not to form a dot shown in FIG. 51 is completed, and the process returns to the image printing process.
- the contents of the number data generation processing (FIG. 50) and the dot formation presence / absence determination processing (FIG. 51) performed during the image printing processing of the fifth embodiment have been described above.
- a pixel group is generated by grouping a predetermined number of pixels, and After determining the classification number and the pixel group gradation value, the number data is generated.
- the pixel group classification number and the pixel group gradation value can be obtained very easily as described above. Then, if the classification number and the pixel group gradation value are known, the number data can be generated extremely easily by referring to the above-mentioned first conversion table.
- the number data generated in this way is much smaller than the data indicating the presence or absence of dot formation for each pixel. It is possible to output data very quickly. That is, in the above-described number data generation processing, the generation and output of the number data can be executed at high speed.
- the order value of the target pixel is obtained by referring to the order value matrix.
- the presence or absence of dot formation for each pixel in the pixel group is determined by referring to the second conversion table using the obtained order value and number. In this way, it is possible to quickly determine whether or not a dot is formed simply by referring to the order value matrix and the second conversion table.
- the process of generating the number data is merely a process of referring to the table, and the classification number and the pixel group gradation value used to refer to the first conversion table are obtained by extremely simple processing. be able to.
- the process of determining the presence or absence of dot formation from the count data is merely a process of referring to a table. For this reason, any of the processes can be performed at a sufficiently practical speed even when a device having no high data processing capability such as the computer 100 is used.
- most of the processing is based on data stored in matrices or tables. It is very simple to simply refer to the data, so it is easy to execute it hardware-wise using an IC chip incorporating a dedicated logic circuit, instead of executing it software-wise using a CPU. is there. If the processing is executed in a hardware manner, it will be possible to execute the processing at a much higher speed, and it will be possible to print an image correspondingly faster.
- the type of dot that can be formed by the color printer 200 is described as one type.
- a printer that forms many types of ink dots a so-called multi Value dot printers.
- the computer 100 directly obtained the number data by referring to the second conversion template.
- the printer 200 directly refers to the second conversion table to determine whether or not to form a dot on the target pixel from the number data and the order value.
- the number data is coded and generated.
- the image printing process of the sixth embodiment as in the fifth embodiment, the entire process is performed according to FIG.
- the generation of the count data on the computer 100 side is performed according to the flowchart shown in FIG.
- an outline of the image printing processing of the sixth embodiment will be briefly described while diverting the flowchart of FIG. 35.
- the image printing process of the sixth embodiment is started, first, the image data is read by the computer 100, and then the color conversion process is performed (steps S100 and S100 in FIG. 35). 2 equivalent). Next, a resolution conversion process is performed to convert the resolution of the image data into a print resolution (corresponding to step S104), and then the number data generation process is started (corresponding to step S107).
- the generated number data is output to the printer 200 side.
- the printer 200 side determines whether or not to form dots.
- a process (equivalent to step S109) is performed, and a process for forming a dot (equivalent to step S110) is performed according to the determination.
- the number data generation process (corresponding to step S107) generates number data for large, medium, and small dots, and encodes the parentheses.
- the color printer 20.0 can form only one type of dot. In the count data generation processing, one type of dot formed in the pixel group is used.
- the color printer 200 can form three types of dots having different sizes, that is, a large dot, a medium dot, and a small dot. For this reason, in the number data generation process of the sixth embodiment, the number data indicating how many large dots, medium dots, and small dots are formed in the pixel group is generated. Also, in order to output the count data efficiently with a small amount of data, the number of large dots, medium dots, and small dots is not output as it is, but is output in a coded state. This method of encoding and outputting is described in FIGS. 21 to 26 as the first embodiment.
- the computer 100 of the sixth embodiment first determines the number of large, medium, and small dots to be formed by using the dither method (FIG. 21 or FIG. 25), and thereafter, the first conversion table (FIG. 21).
- the number data is coded using Fig. 26).
- coded number data is generated through a two-step process. In the process described above, the number of large, medium, and small dots to be formed in a pixel group is determined using the dither method, and the obtained combination of the number of dots is coded and then supplied to the printer. It was explained as having gone through.
- the image data of the pixel group can be directly converted to coded number data and output to the color printer 200. It is. This makes it possible to generate the quantity data very quickly, and the processing for generating the quantity data becomes extremely simple. As a result, it is possible to generate the number data at a sufficiently practical speed without using a device such as a computer having a high processing capability.
- the count data generation process shown in FIG. 27 can be adopted. In this process, the pixel group classification number and the pixel When the gradation value of the group is determined (FIG.
- step S702 the coded number data is obtained at once from the classification number and the gradation value of the pixel group by referring to the conversion table.
- Step S704 The method of determining the pixel group classification number and the pixel group gradation value has been described above, and thus the description is omitted here.
- the first conversion table referred to in this processing is shown in FIG.
- coded number data is stored in advance in association with a combination of a pixel group classification number and a pixel group gradation value. Therefore, in the number data generation processing of the sixth embodiment, the classification is immediately performed (one step) by simply determining the classification number of the pixel group and the pixel group gradation value and referring to the first conversion table.
- the color printer 200 of the sixth embodiment receives the coded number data and determines whether or not large, medium and small dots are formed.
- the dot formation presence / absence determination processing of the fifth embodiment described above the presence / absence of dot formation is immediately determined from the number data and the order value by referring to the second conversion table.
- the presence / absence of large / medium / small dot formation can be immediately determined from the coded number data and the order value. It is.
- FIG. 47 An example of the second conversion table used is shown in FIG. The principle of determining the presence or absence of dot formation with reference to a second conversion table as shown in FIG. 47 will be briefly described. As shown in Figure 30 There is a one-to-one relationship between the number of pieces of data obtained and the combination of the numbers of large, medium and small dots. In other words, if one coded number data is provided, the combination of the numbers for various dots can be uniquely determined. On the other hand, when the number of various dots formed in the pixel group is decoded, as shown in FIG.
- the coded number data is immediately obtained by simply referring to the first conversion table. Obtainable. Therefore, the encoded number data can be generated very quickly.
- the dot formation presence / absence determination process of the second embodiment described above when the coded number data is received, the order value of the target pixel is acquired by referring to the order value matrix, and then the number data and the order value are obtained.
- the second conversion table it is possible to determine the presence or absence of formation of various dots without decoding the number data.
- the number data generation processing and the dot formation presence / absence determination processing can both be executed extremely quickly, but in addition to this, the processing contents can be made extremely simple.
- the number data generation processing will be described. If you decide to use the dither method to determine the number of dots without consulting the first conversion table, you will need to perform a complicated process. In addition, the resulting combination of dot numbers must be coded. On the other hand, by referring to the first conversion table, the same processing can be performed by an extremely simple processing as shown in FIG.
- the use of the memory in the image printing process of the sixth embodiment is also described in the first aspect of the present invention.
- the first and second conversion templates are both large enough to fit in a general computer cache memory. It has a small amount of data, and can be fully loaded into image devices such as digital camera 120 and memory of color printer 200.
- image devices such as digital camera 120 and memory of color printer 200.
- the present invention can be suitably applied to a liquid crystal display device or the like that expresses an image in which the gradation changes continuously by dispersing bright spots on the liquid crystal display screen at an appropriate density.
- a liquid crystal display device or the like that expresses an image in which the gradation changes continuously by dispersing bright spots on the liquid crystal display screen at an appropriate density.
- FIG. 52 is an explanatory diagram conceptually illustrating a set spatial frequency characteristic of a dither matrix having a blue noise mask characteristic and a dither matrix having a Darine noise mask characteristic.
- the horizontal axis shows the period instead of the spatial frequency. Needless to say, the shorter the period, the higher the spatial frequency.
- the vertical axis in FIG. 52 indicates the spatial frequency component in each cycle. The frequency components shown are 02527
- the solid line in the figure conceptually shows the spatial frequency component of the blue noise mask.
- the blue noise mask has the largest frequency component in a high frequency region where the length of one cycle is 2 pixels or less. Since the threshold of the Bull noise mask is set to have such a spatial frequency characteristic, when the presence or absence of the dot formation is determined based on the Bull noise mask, the dots are separated from each other. It tends to be formed in a state.
- the broken line in the figure conceptually shows the spatial frequency component of the green noise mask. As shown in the figure, the green noise mask has the largest frequency component in an intermediate frequency region in which one cycle length is from 2 pixels to more than 10 pixels.
- the threshold value of the green noise mask is set to have such spatial frequency characteristics, when the presence or absence of dot formation is determined based on the green noise mask, the threshold value is determined in units of several dots. While the dots are being formed, the mass of the dots tends to be formed in a dispersed state as a whole. Therefore, if the number data of the pixel group is determined or the pixel position is determined based on the dither matrix having such a blue noise mask characteristic or a green noise mask characteristic, processing is performed on a pixel group basis. Nevertheless, a dot can be formed with a distribution reflecting the blue noise mask characteristic or the green noise mask characteristic. In the above description, as shown in FIGS.
- a plurality of ordinal value matrices generated based on the dither matrix are stored in advance, and the number data of the pixel groups is stored.
- the order value matrix corresponding to the pixel group is used to determine whether or not to form dots for each pixel.
- the presence or absence of dot formation may be determined as follows. That is, a plurality of order value matrices are stored in advance, and when the number data is received, whether or not dots are formed for each pixel is determined using one order value matrix randomly selected for each pixel group. May be determined. Further, more simply, it is possible to store only one set of the order value matrix and determine the presence or absence of dot formation for each pixel using this matrix.
Abstract
Description
Claims
Priority Applications (4)
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US10/589,069 US7830553B2 (en) | 2004-02-10 | 2005-02-10 | Image output system for outputting image based on information of number of dots to be formed in predetermined area |
CN200580004501.6A CN1918898B (zh) | 2004-02-10 | 2005-02-10 | 图像输出系统、图像输出装置、图像处理装置及方法 |
EP05710373A EP1722549A4 (en) | 2004-02-10 | 2005-02-10 | PICTURE DISTRIBUTION SYSTEM FOR PUBLISHING AN IMAGE BASED ON INFORMATION ABOUT NUMBER OF POINTS TO BE MADE IN A PREFERRED AREA |
US12/925,234 US8023154B2 (en) | 2004-02-10 | 2010-10-15 | Image output system for outputting image based on information of number of dots to be formed in predetermined area |
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JPH10262151A (ja) * | 1997-03-19 | 1998-09-29 | Seiko Epson Corp | グレースケール画像のハーフトーニング方法、およびグレースケール画像のハーフトーニング手段を有する装置 |
JP2002185789A (ja) * | 2000-10-06 | 2002-06-28 | Seiko Epson Corp | 画像処理装置、印刷制御装置、画像処理方法、および記録媒体 |
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US5463703A (en) * | 1994-02-10 | 1995-10-31 | Lin; Bob | Dither picture data pre-compression processing method |
JPH07322074A (ja) * | 1994-05-16 | 1995-12-08 | Internatl Business Mach Corp <Ibm> | ディザリングされた2レベル・イメージ・ファイルを処理するためのデータ処理装置および方法 |
JP3387738B2 (ja) * | 1996-06-28 | 2003-03-17 | 株式会社沖データ | 画像パターン変換装置 |
US5966467A (en) * | 1997-09-12 | 1999-10-12 | Xerox Corporation | System for compressing and decompressing binary representations of dithered images |
JP3688938B2 (ja) | 1999-03-18 | 2005-08-31 | 株式会社リコー | 画像データ生成方法、装置および記録媒体 |
JP2002271623A (ja) | 2001-03-13 | 2002-09-20 | Fuji Xerox Co Ltd | 画像処理装置および画像処理プログラム |
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2005
- 2005-02-10 WO PCT/JP2005/002527 patent/WO2005076592A1/ja not_active Application Discontinuation
- 2005-02-10 EP EP05710373A patent/EP1722549A4/en not_active Withdrawn
- 2005-02-10 US US10/589,069 patent/US7830553B2/en not_active Expired - Fee Related
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2010
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JPH08116440A (ja) * | 1994-10-17 | 1996-05-07 | Fuji Xerox Co Ltd | 階調画像2値化装置 |
JPH08307720A (ja) * | 1995-05-12 | 1996-11-22 | Seiko Epson Corp | カラー画像の階調数変換方式及び方法 |
JPH10262151A (ja) * | 1997-03-19 | 1998-09-29 | Seiko Epson Corp | グレースケール画像のハーフトーニング方法、およびグレースケール画像のハーフトーニング手段を有する装置 |
JP2002185789A (ja) * | 2000-10-06 | 2002-06-28 | Seiko Epson Corp | 画像処理装置、印刷制御装置、画像処理方法、および記録媒体 |
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Also Published As
Publication number | Publication date |
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EP1722549A1 (en) | 2006-11-15 |
US20070171439A1 (en) | 2007-07-26 |
US7830553B2 (en) | 2010-11-09 |
US8023154B2 (en) | 2011-09-20 |
US20110032574A1 (en) | 2011-02-10 |
EP1722549A4 (en) | 2007-04-18 |
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