JP3581381B2 - Image processing method and image processing apparatus - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an image processing method and an image processing apparatus for outputting information.
[0002]
[Prior art]
Generally, in an output device that forms an image based on input color image data, a problem in performing color reproduction is a difference between a color reproduction range on an input side and a color reproduction range of an output device. A CRT monitor device or the like is a light-emitting device and performs color reproduction by adding and mixing light source colors RGB, while a printer device and the like is a device that performs color reproduction by subtracting and mixing YMCK ink. The color reproduction range of the monitor and the printer is different due to the difference in these color reproduction methods, and the color reproduction range of the normal monitor is larger.
[0003]
FIG. 8A shows a state where the color gamut is different. That is, 80 shown in FIG. 8A is a color space that can be logically considered according to the standard such as NTSC in the La ^* b ^* uniform color space, and is a color space that can be taken as input data from the host computer. 81 is the color reproduction range of the monitor, and 82 is the color reproduction range of the printer.
[0004]
When an input color image is output by an output device, it is necessary to associate colors outside the color reproduction range of the output device with appropriate colors within the reproduction range. This is generally called color space compression. In a conventional output device, only one type of color space compression method is mounted, or no color space compression method is mounted, and color space compression is performed on the host computer side.
[0005]
[Problems to be solved by the invention]
In general, there are a plurality of color space compression methods, which are used depending on the purpose. FIG. 8 shows this state. Here, a case is considered in which the color gamut of the monitor reproduction range is compressed to that of the printer.
In (a), 83 and 84 are the brightest colors (white points) within the reproduction range of the monitor and the printer, respectively, and 85 and 86 are the darkest colors (black points).
[0006]
The first compression method maps a monitor white point and a black point to a printer white point and a black point, respectively, as indicated by a dotted line in (b), and correlates other colors with the white point and the black point. Is maintained so that is maintained. That is, the broken-line figure in FIG. 7B is converted to be similar to 81. This is suitable for processing image data such as photographs having many colors.
[0007]
In the second compression method, as shown in (c), mapping is performed on the outer edge of the reproduction range of the printer without changing L * (brightness). This is suitable for faithfully reproducing colors such as logo marks (spot colors).
In the third compression method, as shown in (d), compression is performed without changing the saturation as much as possible while sacrificing lightness. Suitable for Computer Graphics (CG).
[0008]
As described above, the optimal color space compression method differs depending on the type of image data such as image data, spot color, and CG. Therefore, it is desirable to use the appropriate compression method depending on the purpose.
However, in the above-described conventional example, only one color space compression method by the output device is prepared, and the above-described compression method cannot be properly used depending on the type of image data. Therefore, there is a drawback that optimal color reproduction is difficult.
[0009]
Further, when performing compression processing by separating the color space compression method on the host computer side, there is a disadvantage that the load on the host computer for the processing is large and the performance of the entire system is reduced.
[0010]
[Means for Solving the Problems]
The present invention has been made for the purpose of solving the above-described problems, and includes the following steps as one means for solving the above-mentioned problems. That is,
An input step of inputting an image composed of a plurality of objects from an external device,
A determination step of analyzing command data indicating the object and determining an image type of the object;
Color processing for selecting one of a plurality of different color space compression processing methods based on the determined image type, and performing color space compression processing on the color data of the object using the selected color space compression method Process and
An expansion processing step of performing expansion processing based on the color data of the object subjected to the color space compression processing;
An output step of outputting data for output expanded by the expansion step ,
The plurality of color space compression methods include at least a color space compression method for preserving saturation and a color space compression method for preserving lightness .
[0011]
Further, the image processing apparatus of the present invention has the following configuration. That is,
Input means for inputting an image composed of a plurality of objects from an external device;
Determining means for analyzing command data indicating the object and determining an image type of the object;
Color processing for selecting one of a plurality of different color space compression processing methods based on the determined image type, and performing color space compression processing on the color data of the object using the selected color space compression method Means,
Expansion processing means for performing expansion processing based on the color data of the object subjected to the color space compression processing;
Output means for outputting data for output expanded by the expansion means ,
The plurality of color space compression methods include at least a color space compression method for preserving saturation and a color space compression method for preserving lightness .
[0012]
【Example】
Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
In this embodiment, a bubble jet (BJ) type color printer is used as an example, but it goes without saying that the present invention can be similarly applied to other output devices such as a color printer of another type and a color monitor.
[0013]
In the present embodiment, input means for inputting image data such as command-format data and image data for output control transmitted from an external device, analysis means for analyzing the input data, and analysis results obtained by the analysis means Expansion means for expanding the input data into data for output, and color processing means constituting a part of expansion means for performing color processing such as color space compression on the input data at the time of expansion by the expansion means; Storing means for storing a plurality of the color processing methods, and selecting means for selecting one of the plurality of color processing methods stored in the storing means. When developing the data into the color processing method, the user can select one of the plurality of color processing methods stored in the color processing method storage means in accordance with the result of analyzing the input data input from the external device by the analysis means. Choose one by the color processing means performing color processing in accordance with the methods of the selected color processing. As a result, the color space compression method can be properly used in the output device according to the input image data, so that optimal color reproduction can be performed without burdening the host computer.
[0014]
Hereinafter, this specific example will be described.
FIG. 1 is a block diagram showing an example of a control circuit constituting a part of an output device according to one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an output device according to the present embodiment, and 2 denotes an external device such as a host computer or a terminal device.
In the output device 1, an input unit 11 forms an input unit for receiving data transferred from the host computer 2. Numeral 12 denotes an analyzing unit 12 which forms an analyzing means for analyzing the input data at the input unit 11 and forming data in an intermediate format used by the expanding unit 13 which will be described later. The data in the intermediate format will be described later.
[0015]
Reference numeral 13 denotes a developing unit that performs various processes in accordance with the intermediate format data created by the analysis unit 12 and forms a developing unit that converts the data into output data used when the output unit outputs the data. Reference numeral 14 denotes a color processing unit which forms color processing means for performing color processing in the developing unit. The term "color processing" used herein refers to, for example, a process of finally converting input data in RGB notation of a monitor, which is an input value, into data in CMYK notation, which is a color signal for output of a printer. And a color space compression process for compensating for the color reproduction range of the printer.
[0016]
Reference numeral 15 denotes a selection unit that forms selection means for selecting a color processing method when the color processing unit 14 performs color processing from a color processing method storage unit described later. Reference numeral 16 denotes a color processing method storage unit that forms storage means for storing a plurality of types of color processing methods when the color processing unit 14 performs color processing. Reference numeral 17 denotes an output unit which forms output means for forming an output image using output data from the developing unit 13. The output data is bitmap data for one page here, and is prepared for each of CMYK four colors. The output unit 17 sends the output data to the BJ head, and outputs the data to the printing paper using each of C (cyan), M (magenta), Y (yellow), and K (black) inks.
[0017]
The processing procedure of the control circuit according to the present embodiment having the above configuration will be described below with reference to the flowcharts shown in FIGS. FIG. 2 is a diagram showing a processing procedure when the output device 1 inputs data of one page from the host computer 2 and forms output data.
First, in step S20, one page of data is input from the host computer 2 through the input unit 11. FIG. 5 shows an example of a one-page image to be output in this process. In FIG. 5, reference numeral 50 denotes a text portion composed of a character string; 51, full-color image data obtained by scanning a photograph; 52, registration characters such as a logo mark, which are designated by a registration number, that is, a spot color; CG data such as a pie chart.
[0018]
That is, the host computer 2 converts images in various forms on the monitor as shown in FIG. 5 into input image data to be output by the output device 2, and transmits the input image data. The input data at this time is a command for designating a character code or a character font type, a command for full-color image data and its data portion, a command for CG including color designation, a command for spot color, and the like. , Various commands and data for forming output data.
[0019]
FIG. 6 shows examples of these commands. In FIG. 6, reference numeral 60 denotes an example of a command for image data. Here, the first one byte, “image command”, indicates the type of each command, and the next “CMM (color matching method)” specifies a color processing method (hereinafter CMM) when processing the command sequence. The byte "coordinate" is a byte (a plurality of bytes) for specifying a position in a page when the image is drawn. After that, the data of the image is transmitted last after the necessary byte sequence.
[0020]
Similarly, 61 and 62 show examples of a CG command and a character color designation command, respectively. Here, the “color designation” byte may be described in RGB notation, or may be designated by a spot color whose color is designated by a registration number. The CMM type can be specified for each command string as in the case of 60. Therefore, an optimum CMM can be designated according to each command sequence.
[0021]
For example, as described above with reference to FIG. 8, a method using color space compression (hereinafter referred to as CMM) shown in FIG. 8B is suitable for image data, and a method shown in FIG. Hereinafter, CMM2) is suitable, and the method of FIG. 8D (hereinafter CMM3) is suitable for CG.
Subsequently, in step S21, the input data is analyzed by the analysis unit 12 to form intermediate format data in page units. FIG. 7 shows an example of the intermediate format data. The intermediate format data is data that is used when the developing unit 13 forms output data in the bitmap format, and is recorded for each input command sequence. That is, 70 to 73 are examples of records indicating text, spot color text, image data, and CG data, respectively.
[0022]
The entries constituting the record differ depending on the record type. However, as shown in FIG. 7, the XY coordinates, the object type, the CMM type, the designated color, the data size, the character code, the character type, and the address pointer of the data storage area are usually shown in FIG. And so on.
Next, in step S22, the analysis unit 12 determines whether the input data has been completed for one page. This is usually performed based on whether or not the page break command “FF” has been received. If the input data has not been completed for one page, the process returns to step S20, where input and analysis are continuously performed to create intermediate format data.
[0023]
If it is determined in step S22 that the input data has been completed for one page, the process proceeds to step S23, where expansion / color processing is performed. This is performed by the developing unit 13 and the color processing unit 14 based on the intermediate format data. That is, the developing unit 13 develops each record of FIG. 7 one by one on the bit map memory. For example, in the case of the image data record 72, the image data is read based on the image storage area address pointer using the XY coordinates (40, 30) on the bit map as the upper left point of the image data, and the size is (500 × 800). Paste on the bitmap. Similarly, all records are expanded on the bitmap memory.
[0024]
The color processing unit 14 performs color processing for each object based on the CMM type and color information stored in the record in step S23. FIG. 3 shows a flowchart of the processing in the color processing unit 14 at this time.
In FIG. 3, first, in step S30, the color information in the record to be processed is read. In this case, the color information may be in RGB notation as described above, or may be color specified by a spot color number. Next, in step S31, CMM type information in the record is obtained. Next, the selection unit 15 selects the current CMM according to the CMM information.
[0025]
That is, it is first determined in step S32 whether the CMM information is CMM1, and if it is CMM1, in step S36, CMM1 is set as the current CMM. Similarly, the determination of CMM2 is performed in steps S33 and S35, and if none of the above applies, the current CMM is set to CMM3 in step S34. Each CMM is stored in the color processing method storage unit 16, and is sequentially set as a current CMM by the selection unit 15 as needed.
[0026]
Next, in step S37, color processing by the current CMM is performed. In the color processing, input data in RGB notation of the monitor, which is an input value, and color data designated by a spot color are converted into data in CMYK notation, which is an output color signal of the printer, by the color processing unit 14. Also, a color space compression process for compensating for the difference in the color reproduction range between the monitor and the printer, which occurs at that time, is included.
[0027]
The color processing method in the color processing unit 14 depends on the selected CMM method, but a table for preparing a color conversion table in advance and obtaining an output value by referring to the table in accordance with an input value. A look-up method, a method of performing an operation by a conversion expression such as a matrix operation on an input value, and calculating an output value may be considered.
The developing unit 13 forms data in four types of CMYK bitmap memories based on output values obtained by the color processing unit 14 for each designated CMM. That is, the color processing unit 14 is a black box in the developing unit 13 and outputs an optimum output value according to the input value and the designated CMM.
[0028]
When the four types of CMYK bitmap data have been created, the process of step S23 ends, and then, in step S24, the created data is output. Output is performed in the following procedure. That is, the bitmap data created in step S23 is converted by the output unit 17 into a form suitable for the BJ head to perform printing. The suitable form here depends on the shape of the BJ head. For example, when the BJ head has 64 vertical nozzles, the four types of CMYK bitmap data are divided into blocks each having 64 rasters from the top. .
[0029]
After converting the data, the output unit 17 feeds the printing paper, sequentially transmits the CMYK data blocks to the BJ head, and drives the BJ head to output the printing paper. After that, the output unit 17 feeds the paper by the height of the head (in this case, 64 dots). After repeating these series of operations (ie, data block transfer, output, and paper feed) for one page, the output unit 14 discharges the paper and finishes printing for one page.
[0030]
As described above, according to the present embodiment, it is possible to selectively use the color space compression method according to the input image data in the output device, and thus it is possible to perform optimal color reproduction without burdening the host computer. Become.
[Second embodiment]
Next, a second embodiment based on the first embodiment described above will be described below. In the second embodiment, while the first embodiment specifies the CMM type by a command from the host computer, the output device automatically determines the optimal CMM from the object specification in the command. It is configured to select. That is, as shown in FIG. 6B, the designation of the CMM type can be omitted from the command sequence.
[0031]
The basic configuration of the second embodiment is the same as that of the first embodiment, and the control is different. Hereinafter, portions different from the above-described embodiment will be described.
FIG. 4 shows the flow of the color processing in the second embodiment. 4, first, in step S40, color information in a record to be processed is read in the same manner as in the first embodiment. In this case, the color information may be in RGB notation as described above, or may be color designated by a so-called palette color or spot color number.
[0032]
Next, in step S41, object type information in the record is obtained. In the case of the second embodiment, there is no entry of CMM type information in the record. Next, the selection unit 15 selects the current CMM according to the object type information. That is, it is first determined in step S42 whether or not the object type information is image data. If the object type information is an image, in step S46, CMM1 which is the most suitable color space compression method for the image is set in the current CMM. Similarly, in step S43, it is determined whether or not the color information is a spot color. If the color information is a spot color, CMM2 is set as the current CMM in step S45. If none of the above applies, in step S44, CMM3 is set as the current CMM.
Next, as in the first embodiment, in step S47, color processing by the current CMM is performed. Other processes are the same as those shown in the first embodiment.
[0033]
As described above, according to the second embodiment, in addition to the effects of the above-described first embodiment, the configuration is such that the optimum CMM is automatically selected on the output device side from the object designation in the command from the host computer. Therefore, designation of the CMM type can be omitted from the command sequence.
The present invention may be applied to a system including a plurality of devices or an apparatus including one device.
[0034]
Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus.
[0035]
【The invention's effect】
As described above, according to the present invention, when input image data including a plurality of objects is input from an external device, a plurality of different color space compression methods are determined according to an object type determined by command data indicating each object. since it is possible to selectively use, it enables optimum color reproduction without the burden of the host computer, it is possible to obtain an ideal output, simple structure, reliable optimal color space compression process in the control Color space compression can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an example of a control circuit in an output procedure according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating an output process for one page in the embodiment.
FIG. 3 is a flowchart illustrating color processing according to the embodiment.
FIG. 4 is a flowchart showing color processing in a second embodiment according to the present invention.
FIG. 5 is a diagram illustrating an example of an image to be processed in the present embodiment.
FIG. 6 is a diagram illustrating an example of an input command sequence in the embodiment.
FIG. 7 is a diagram showing an example of intermediate format data in the embodiment.
FIG. 8 is a conceptual diagram illustrating a color reproduction range and color space compression.
[Explanation of symbols]
Reference Signs List 1 output device 2 host computer 11 input unit 12 analysis unit 13 expansion unit 14 color processing unit 15 selection unit 16 color processing method storage unit 17 output unit

Claims (4)

An input step of inputting an image composed of a plurality of objects from an external device,
A determination step of analyzing command data indicating the object and determining an image type of the object;
Color processing for selecting one of a plurality of different color space compression processing methods based on the determined image type, and performing color space compression processing on the color data of the object using the selected color space compression method Process and
An expansion processing step of performing expansion processing based on the color data of the object subjected to the color space compression processing;
An output step of outputting data for output expanded by the expansion step ,
The image processing method according to claim 1, wherein the plurality of color space compression methods include a color space compression method for storing at least saturation and a color space compression method for storing brightness . The image processing method according to claim 1, wherein the image types include text, text by spot color, image, and CG. Input means for inputting an image composed of a plurality of objects from an external device;
Determining means for analyzing command data indicating the object and determining an image type of the object;
Color processing for selecting one of a plurality of different color space compression processing methods based on the determined image type, and performing color space compression processing on the color data of the object using the selected color space compression method Means,
Expansion processing means for performing expansion processing based on the color data of the object subjected to the color space compression processing;
Output means for outputting data for output expanded by the expansion means ,
The image processing apparatus, wherein the plurality of color space compression methods include at least a color space compression method for storing saturation and a color space compression method for storing brightness . The image processing apparatus according to claim 3, wherein the image types include text, text in a spot color, an image, and CG.

Images