JP2009118161A - Image processing device, image processing method, program thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a user to easily measure and register the rear surface image transmission characteristic of paper used for preventing the reproduction of an image on the rear surface of an original on the front surface when the user copies a both-side printed original. <P>SOLUTION: Pattern image data for measurement used for measuring the rear surface image transmission characteristic of a recording medium are stored, and the position of a measurement coordinates of the pattern image data for measurement is stored. When an instruction to measure the rear surface image transmission characteristic of the recording medium is inputted, a pattern image for measurement is formed on the recording medium based on the pattern image data for measurement. The formed pattern image for measurement is scanned, and from the obtained image data, image data at a specified coordinates are obtained based on the position of the measurement coordinates. Based on the obtained image data, the rear surface image transmission characteristic is calculated and the calculated data are stored. A process for preventing a transfer of an image from the rear to the front surface is performed on input image data according to the rear surface image transmission characteristic. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for preventing an image on the back side of a document from being reproduced on the front surface when copying a document that is printed on both sides in an image processing apparatus.

  Conventionally, in a device for reading a document such as a copying machine or a scanner, as a technique for preventing so-called show-through in which an image on the back side of a document is reproduced on the front surface, a level for a user to reduce the image reproduction density from the operation screen is set. There is a way to specify. In addition, a method of erasing a show-through image using the scanned image data on the back surface (see, for example, Patent Document 1), or a corresponding processing coefficient is applied by the user selecting from a plurality of document types prepared in advance. A method (for example, see Patent Document 2) has been common. In addition, there is a technique (for example, refer to Patent Document 3) that acquires light transmittance of a document and switches a processing method and sets a coefficient for removing a show-through image based on the data.

JP 2005-252788 A JP 2002-252767 A JP 2006-93791 A

  However, among the conventional techniques described above, the method using the back surface data has a problem that the amount of calculation is large, the cost of the apparatus increases, and the processing speed becomes slow. In the method in which the calculation amount is reduced by selecting a processing coefficient, it is difficult for the user to appropriately specify a setting value from options prepared in advance, and there is a case where a setting value suitable for a document does not exist. was there. Further, in the technology using the light transmittance of the document, there is a problem that a new part is required in comparison with the conventional product due to the configuration of the apparatus, leading to a significant increase in cost.

  In order to solve the above-described problem, the invention described in claim 1 is an image processing apparatus, wherein an image input unit that scans a document to obtain image data, and an image is recorded on a recording medium based on the image data. Image forming means for forming, image data storage means for holding pattern image data for measurement for measuring the back surface image transmission characteristics of the recording medium, and coordinate storage for holding measurement coordinate positions of the pattern image data for measurement A measuring pattern for causing the recording medium to form a measurement pattern image on the recording medium based on the measurement pattern image data; and an operation means for giving an instruction to measure the back surface image transmission characteristic of the recording medium. The image input unit scans and acquires the measurement pattern image formed by the measurement pattern image formation unit. Measurement data acquisition means for acquiring image data of predetermined coordinates from image data based on the measurement coordinate position held in the coordinate storage means, and back image transmission based on the image data acquired by the measurement data acquisition means Back side image transmission characteristic calculation means for calculating characteristics, back side image transmission characteristic storage means for holding data calculated by the back side image transmission characteristic calculation means, and the back side for image data input by the image input means And a show-through prevention processing means for performing the show-through prevention processing in accordance with the image transmission characteristics.

  According to a second aspect of the present invention, in the image processing apparatus according to the first aspect, the back surface image transmission characteristic storage unit stores two or more types of back surface image transmission characteristics, and the operation unit includes: A selection of one type of characteristic to be applied to the show-through prevention processing means is accepted from the two or more types of back surface image transmission characteristics.

  According to a third aspect of the present invention, in the image processing apparatus according to the first or second aspect, the measurement pattern image formed by the measurement pattern image forming unit is formed on both surfaces of the recording medium. The images formed on both sides are arranged at positions that do not overlap each other with the recording medium interposed therebetween.

  According to a fourth aspect of the present invention, in the image processing apparatus according to any one of the first to third aspects, the measurement pattern image is a measurement region having a certain area or more and having a constant density. One or more types are arranged.

  According to a fifth aspect of the present invention, in the image processing apparatus according to any one of the first to fourth aspects, the measurement pattern image has a constant area composed of a constant color and a constant density. The above measurement region is characterized in that one or more types of density are arranged for every two or more types of colors.

  According to a sixth aspect of the present invention, in the image processing apparatus according to the fifth aspect, the back surface image transmission characteristic calculating means performs one calculation with a predetermined weighting for each color of the measurement pattern image. The back surface image transmission characteristic is calculated.

  According to a seventh aspect of the present invention, in the image processing apparatus according to any one of the first to sixth aspects, the back side image transmission stored by the back side image transmission characteristic storage means at the time of document copy processing. In accordance with characteristics, there is an operation means for instructing execution of the show-through prevention process, and an initial value of the setting for the show-through prevention process displayed on the operation screen of the operation means is the back-side image transmission characteristic. The setting for the show-through prevention process can be changed arbitrarily from the initial value of the setting. It is characterized by being.

  The invention according to claim 8 is the image processing apparatus according to any one of claims 1 to 7, wherein the measurement pattern image formed by the measurement pattern image forming means is the image processing apparatus. The present invention is also applicable to other functions of the recording medium, and the other functions are simultaneously performed by using an operation means for giving an instruction to measure the back surface image transmission characteristics of the recording medium. And

  Other functions include color matching in the image forming engine. According to the present invention, it is possible to perform processing such as color matching simultaneously with measurement of the back surface image transmission characteristics.

  Further, the invention according to claim 9 is an image processing apparatus, wherein holding means for holding pattern image data for measurement for measuring the back surface image transmission characteristics of a recording medium, and in response to a user instruction, A forming unit that forms a measurement pattern image corresponding to the measurement pattern image data on a recording medium; a calculation unit that reads the measurement pattern image formed by the forming unit and calculates a back surface image transmission characteristic; Storage means for storing the back-side image transmission characteristics calculated by the calculation means, and processing means for performing a show-through prevention process on the input image according to the back-side image transmission characteristics stored by the storage means. It is characterized by that.

  The invention according to claim 10 is an image processing method executed by the control means in the image processing apparatus, wherein the pattern image data for measurement for measuring the back surface image transmission characteristics of the recording medium is the image. An image data storage step to be stored in the storage device of the processing device, a coordinate storage step to store the measurement coordinate position of the measurement pattern image data in the storage device of the image processing device, and a back surface image transmission characteristic of the recording medium are measured. An operation step for receiving an instruction input, a measurement pattern image forming step for forming a measurement pattern image on a recording medium based on the measurement pattern image data, and a measurement pattern formed by the measurement pattern image formation step From the image data acquired by scanning the image, to the storage device of the image processing device by the coordinate storage step A measurement data acquisition step for acquiring image data of predetermined coordinates based on the memorized measurement coordinate position, and a back surface image transmission property calculation step for calculating a back surface image transmission property based on the image data acquired by the measurement data acquisition step And a back side image transmission characteristic storage step for storing the data calculated in the back side image transmission characteristic calculation step in a storage device of the image processing apparatus, and an image input step for acquiring image data by scanning a document. And a show-through prevention process step of performing a show-through prevention process on the image data in accordance with the back surface image transmission characteristics.

  The invention according to claim 11 is an image processing method executed by the control means in the image processing apparatus, and holds measurement pattern image data for measuring the back surface image transmission characteristics of the recording medium. A holding step; a forming step of forming a measurement pattern image according to the measurement pattern image data on a recording medium in accordance with a user instruction; and reading the measurement pattern image formed in the forming step. , For the input image according to the calculation step for calculating the back surface image transmission characteristics, the storage step for storing the back surface image transmission characteristics calculated in the calculation step, and the back surface image transmission characteristics stored in the storage step, And a processing step of performing a show-through prevention process.

  Further, the steps in the image processing method can be configured as a program that is executed by a computer included in various image processing apparatuses or information processing apparatuses. Then, by causing the computer to read this program, the computer can execute the image processing method. The program can be read by the computer via a computer-readable storage medium storing the program.

  In this specification, the image processing apparatus includes a general-purpose information processing apparatus capable of executing the processing according to the present invention in addition to a dedicated image processing apparatus and an image forming apparatus.

  According to the present invention, the user can easily measure and register the back surface image transmission characteristics of a sheet used as a document. Particularly in offices where the number of types of paper to be used is limited to several, an easy registration operation is performed once, so that appropriate show-through prevention processing setting can be easily performed for many subsequent copies. .

  In addition, even when the characteristics of the backside image transmission characteristics change, such as when the characteristics of the lamp for irradiating the original when reading the original change, an appropriate setting value is obtained by a simple registration operation by the user. It becomes possible.

[First Embodiment]
FIG. 1 shows an external appearance of a digital multi-function peripheral 001 suitable as the first embodiment of the present invention.
A scanner unit 200 shown in FIG. 1 illuminates an image on a paper sheet as a document, and scans an RGB color image from a charge amount obtained by scanning a three-line CCD provided with R, G, and B color filters (not shown). Convert to electrical signals representing data. When a user sets a document on the tray 202 of the document feeder 201 and gives a reading start instruction from the operation unit 400, the CPU 103 gives a reading instruction to the scanner 200, and the feeder 201 feeds document sheets one by one and reads a document image. Perform the action.

  The printer unit 300 shown in FIG. 1 is a part that converts raster image data into an image on paper. The printing method includes an electrophotographic method and an ink jet method, but is not particularly limited. Activation of the printing operation is started by an instruction from the CPU 103. The paper cassette 302 is a part that is set for feeding paper to the printer, and may have a plurality of paper feed stages so that different paper sizes or different paper orientations can be selected. The paper discharge tray 303 receives paper that has been printed.

FIG. 2 is a block diagram for explaining the configuration of the controller 100 of the digital multifunction peripheral 001 in more detail.
The controller 100 is electrically connected to the scanner unit 200 and the printer unit 300, and on the other hand, is connected to an external computer (not shown) and other external devices via the LAN 500 and the WAN 600. As a result, image data and device information can be input and output.

  The CPU 103 (control means) comprehensively controls access to various connected devices based on a control program stored in the ROM 108, and also comprehensively controls various processes performed in the controller 100. A RAM 107 (storage means) is a system work memory for the operation of the CPU 103 and also a memory for temporarily storing image data. The RAM 107 includes a nonvolatile SRAM that retains stored contents even after the power is turned off and a DRAM that erases the stored contents after the power is turned off. The ROM 108 stores a boot program for the apparatus. The HDD 109 (storage means) is a hard disk drive and can store system software and image data.

  The operation unit interface 104 is an interface unit for connecting the system bus 101 and the operation unit 400. The operation unit interface 104 receives image data to be displayed on the operation unit 400 from the system bus 101 and outputs the image data to the operation unit 400 and outputs information input from the operation unit 400 to the system bus 101.

  A network interface 105 is connected to the LAN 500 and the system bus 101 to input / output information. The modem 106 is connected to the WAN 600 and the system bus 101 and inputs / outputs information. The binary image rotation unit 116 converts (rotates) the direction of binary image data before transmission. The binary multi-value image compression / decompression unit 117 converts the resolution of the binary image data before transmission into a predetermined resolution or a resolution that matches the other party's ability. For compression and expansion, methods such as JBIG, MMR, MR, and MH are used. The image bus 102 is a transmission path for exchanging image data, and is configured by a PCI bus or IEEE1394.

  The scanner image processing unit 150 corrects, processes, and edits image data received from the scanner unit 200 via the scanner interface 113. Details of processing performed by the scanner image processing unit 150 will be described later.

  The compression unit 112 receives the image data and divides the image data into blocks of 32 pixels × 32 pixels. The 32 × 32 pixel image data is referred to as tile data. FIG. 3 conceptually represents this tile data. In a document (paper medium before reading), an area corresponding to the tile data is referred to as a tile image. The tile data is added with the average luminance information in the 32 × 32 pixel block and the coordinate position of the tile image on the document as header information. Further, the compression unit 112 compresses image data including a plurality of tile data. The decompression unit 114 decompresses image data composed of a plurality of tile data, rasterizes the data, and sends the raster data to the printer image processing unit 160.

  The printer image processing unit 160 receives the image data sent from the decompression unit 114 and performs predetermined image processing. The image data after image processing is output to the printer unit 300 via the printer interface 115. Details of processing performed by the printer image processing unit 160 will be described later.

  The image conversion unit 120 performs a predetermined conversion process on the image data, and includes a processing unit as described below.

  The decompression unit 121 decompresses the received image data. The compression unit 122 compresses the received image data. The rotation unit 123 rotates the received image data. The scaling unit 124 performs resolution conversion processing (for example, 600 dpi to 200 dpi) on the received image data. The color space conversion unit 125 converts the color space of the received image data. The color space conversion unit 125 further performs a known LOG conversion process (RGB → CMY) and a known output color correction process (CMY → CMYK). The binary multi-value conversion unit 126 converts the received two-gradation image data into 256-gradation image data. Conversely, the multi-level binary conversion unit 127 converts the received 256-gradation image data into 2-gradation image data using a technique such as error diffusion processing.

  The synthesizer 130 synthesizes the received two image data to generate one piece of image data. When combining two pieces of image data, a method of using an average value of luminance values of pixels to be combined as a combined luminance value, or a luminance value of a pixel having a brighter luminance level, A method for obtaining a luminance value is applied. In addition, it is possible to use a method in which the darker pixel is used as a synthesized pixel. Furthermore, a method of determining a luminance value after synthesis by a logical sum operation, a logical product operation, an exclusive logical sum operation, or the like between pixels to be synthesized is also applicable. These synthesis methods are all well-known methods. The thinning unit 129 performs resolution conversion by thinning out the pixels of the received image data. The moving unit 128 adds a margin part to the received image data or deletes the margin part.

  The RIP 110 receives intermediate data generated based on PDL code data transmitted from an external computer or the like, and generates multi-value bitmap data. The compression unit 111 compresses the bitmap data generated by the RIP 110 to obtain tile data.

Next, details of the scanner image processing unit 150 will be described.
FIG. 4 is a block diagram illustrating a detailed configuration of the scanner image processing unit 150.

Reference numeral 151 denotes a sub-scanning color misregistration correction unit that corrects color misregistration in the sub-scanning direction of the input image. For this correction, for example, processing by 1 × 5 size matrix calculation is performed on image data for each color. Is called.
Reference numeral 152 denotes a main scanning color misregistration correction unit that corrects color misregistration in the main scanning direction of an input image. Is called.
Reference numeral 153 denotes an image area determination unit that identifies an image type in the input image. For example, pixels constituting each image type, such as a photograph part / character part, a chromatic part / achromatic part, etc. in the input image. Identify and generate attribute flag data indicating the type in pixel units.

Reference numeral 154 denotes a filter processing unit that arbitrarily corrects the spatial frequency of the input image. For the correction, for example, processing by a matrix operation of 9 × 9 size is performed.
Reference numeral 155 denotes a histogram processing unit that samples and further counts image signal data in the input image. For example, it determines whether the input image is a color image or a monochrome image, and also determines the background level of the input image. Is called.
Reference numeral 156 denotes an input color correction unit that corrects the color of the input image. For example, the input color correction unit 156 performs processing such as converting the color space of the input image into an arbitrary color space.

  The processing in the scanner image processing unit 150 is not limited to the processing using all of the sub-scanning color misregistration correction unit 151 to the input color correction unit 156 described above, and other image processing modules may be added. , May be deleted. Furthermore, the processing order of the sub-scanning color misregistration correction unit 151 to the input color correction unit 156 shown in FIG. 4 is not limited to this.

Next, details of the printer image processing unit 160 will be described.
FIG. 5 is a block diagram illustrating a detailed configuration of the printer image processing unit 160.

  Reference numeral 161 denotes a background removal unit, which removes the background color of image data, that is, unnecessary background fogging. For the removal process, for example, a 3 × 8 matrix operation or a background removal process using a one-dimensional lookup table (LUT) is performed.

  A monochrome generation unit 162 converts color image data to monochrome data and converts color image data, for example, RGB data to gray (Gray) single color when printing as a single color. For example, a 1 × 3 size matrix calculation is performed by multiplying RGB by an arbitrary constant to obtain a gray signal.

Reference numeral 163 denotes an output color correction unit that performs color correction in accordance with the characteristics of the printer unit 300 that outputs image data. For the correction, for example, processing by 4 × 8 size matrix calculation or direct mapping is performed.
Reference numeral 164 denotes a filter processing unit that arbitrarily corrects the spatial frequency of the image data. For the correction, for example, 9 × 9 size matrix calculation processing is performed.

Reference numeral 165 denotes a gamma correction unit that performs gamma correction in accordance with the characteristics of the output printer unit 300. A normal one-dimensional lookup table (LUT) is used for the correction.
Reference numeral 166 denotes a non-linear processing unit that performs a process for suppressing the amount of toner used when the toner saving mode is effective, in addition to the show-through prevention process. Details of the show-through prevention processing according to the present invention will be described later.
A pseudo halftone processing unit 167 performs arbitrary pseudo halftone processing in accordance with the number of gradations of the output printer unit 300, and performs arbitrary screen processing such as binarization and binarization and error diffusion processing. .

  The processing in the printer image processing unit 160 is not limited to the processing using all of the background removal unit 161 to the pseudo halftone processing unit 167 described above, and other image processing modules may be added. , May be deleted. Furthermore, the processing order of the background removal unit 161 to the pseudo halftone processing unit 167 shown in FIG. 5 is not limited to this order.

Next, the flow of show-through level registration processing will be described with reference to FIGS.
FIG. 6 is a diagram illustrating a processing flow of show-through level registration, FIG. 7 illustrates an example of a measurement pattern, and FIG. 8 illustrates an example of transition of an operation screen.

  First, a sheet (recording medium) for measuring the show-through level is set in the sheet cassette 302 to prepare for printing a measurement pattern. In step S601, the user selects a paper number to be registered or registered. That is, in step S601, the input of the paper number selected by the user is received. An example of the operation screen at this time is shown in FIG. In this example, no. 1-No. No. 3 is registered, and “No registration” No. 4 is selected for new registration. After selecting the number, the registration number selection is completed by pressing the registration button. As shown in FIG. 8 (a), show-through data (data of show-through value to be described later) corresponding to two or more types of paper can be registered, and one type is selected from them. Yes.

  In step S602, a measurement pattern printing instruction is issued. An example of the operation screen at this time is shown in FIG. In this example, the print instruction is achieved by pressing the OK button. When this instruction is given, the CPU 103 (measurement pattern image forming means, control means) reads the measurement pattern information (measurement pattern image data) stored in advance in the HDD 109 (image data storage means) and reads it to the printer unit 300. Command to be output. The printer unit 300 (image forming unit) prints both sides of the measurement pattern on the previously set paper in accordance with the received command (step S603). FIG. 7 shows an example of a measurement pattern.

  Thereafter, the process proceeds to step S604, and a scan operation instruction input from the user is received. At this stage, the user sets the output measurement pattern on the scanner unit 200 according to the operation screen shown in FIG. 8C, and presses the “OK” button to perform the scanning operation. In step S605, the CPU 103 (measurement data acquisition unit, back surface image transmission characteristic calculation unit) calculates a show-through value, which will be described later, based on the reading value of the measurement pattern read by the scanner unit 200 (image input unit). The show-through value is a value corresponding to the show-through level, that is, the back image transmission characteristic. The result is stored in the RAM 107 or HDD 109 in step S606. Meanwhile, a message as shown in FIG. 8D is displayed on the operation screen.

  When the show-through value is normally calculated and stored in the RAM 107 or the HDD 109 (back image transmission characteristic storage means), the process proceeds to step S607, and a registered name is input by the user. At this stage, the user designates an arbitrary registered name from the operation screen shown in FIG. FIGS. 8E and 8F are examples of operation screens at this time. When the input is completed, a confirmation screen shown in FIG. 8G is displayed, and a series of processing ends.

  The measurement pattern shown in FIG. 7 prints the same image on the front and back, but the print area on the front surface and the print area on the back surface are arranged at positions that do not overlap each other across the paper. In this example, there are five density types, and seven density patches each having a constant density are arranged. This is considered so that a patch for acquiring data can be selected from seven when there is a print density difference depending on the position of the paper. Normally, for example, only the reading data of the patch arranged at the center of each density patch may be used, or the average value of seven patches may be used. Each density patch has an area larger than a certain area and forms a measurement region for calculating the show-through value. In the above example, there are five density types and seven density patches are arranged. However, there may be one density patch, that is, one or more density patches.

Next, details of the show-through value calculation process will be described.
FIG. 9 shows a show-through value calculation processing flow executed in step S605 of FIG. The following steps are executed by the CPU 103.

Step S901 is an initialization operation, in which variables for sequentially processing the density patches are initialized. Specifically, the counter i is set to 0, and the number of density patches is set to the variable c. For example, the number of density patches is 5 in the case of the measurement pattern shown in FIG.
In step S902, it is determined whether or not the acquisition of the show-through coefficient for all density patches has been completed (if i <c, the process is not completed).

  If acquisition of the show-through coefficient for all density patches has not been completed, data (r, g, b) of the i-th density patch printed on the surface is acquired in step S903. Here, r, g, and b are image signals from the scanner, and are 8-bit data of red, green, and blue, respectively. Note that the data of the measurement coordinate position, which is the position for acquiring each data of the density patch, is stored in advance in the HDD 109 (coordinate storage means), and the density patch data is acquired from this predetermined coordinate position.

  In step S904, data (r ′, g ′, b ′) obtained by reading the i-th density patch printed on the back surface from the front surface (that is, reading the show-through) is acquired.

  In step S905, using these data, the show-through coefficient a [i] of the i-th density patch is calculated according to the following equation (1).

  However, among r, g, and b, the color component that is 255 is excluded from Expression (1). For example, when (r, g, b) = (255, 200, 240) and (r ′, g ′, b ′) = (255, 250, 255), the show-through coefficient a [i] Calculated as shown in (2).

  Next, in step S906, the counter i is incremented, and the process returns to step S902.

  Thereafter, steps S902 to S906 are repeated until the show-through coefficient a is obtained for all density patches.

  Thereafter, when the acquisition of the show-through coefficient for all density patches is completed, the process proceeds from step S902 to step S907. In step S907, a final show-through value f is obtained. The show-through value f is the maximum value of the show-through coefficient a of each density patch as shown in the following equation (3).

  The series of processing flows for registering the show-through level for a certain type of paper has been described above.

Next, a description will be given of a processing flow when a copy operation is performed using a printed matter using paper registered by the above method as a document.
First, an operation screen for setting to prevent show-through during copying will be described. FIG. 10 shows an example of a screen for setting to prevent show-through during copying (during copy processing).
FIG. 10A shows the No. from the original paper type corresponding to the registered show-through data. 1: A screen example in which plain paper A is selected is shown. Since the plain paper A is a paper whose show-through level is slightly easier to show-through than the standard, the default position of the slider for manual adjustment is slightly to the right of the center, that is, the effect of preventing show-through is large. The user can change the strength of the show-through prevention effect by adjusting this slider according to his / her preference.

FIG. 3: A screen example in which the cardboard A is selected is shown. Since the thick paper A has no show-through, the default position of the slider is the leftmost position, which is substantially the same setting as the show-through prevention function OFF. The user performs the above-described setting and setting confirmation work regarding the show-through prevention function to perform the copy operation.
As described above, the user can select the original paper type (that is, the initial value of the setting for the show-through prevention process can be changed according to the back-side image transmission characteristics), and the show-through level can be changed. Manual adjustment is also possible. In addition to the default setting of the (registered) show-through level according to the original paper type as described above, a specific original paper type (for example, frequently used paper type) is set as a default value as an initial value. May be.

Here, processing from when the copy operation starts until when the show-through value for actually performing the show-through prevention processing is set will be described.
FIG. 11 shows the internal processing flow.
When an instruction to start copying is given, both sides of the document are scanned in step S1101. The duplex scanning method may be realized by turning the document over by the user and placing it on the document table, or the document feeder may automatically reverse the document. Furthermore, a document feeder having a mechanism for reading both sides simultaneously may be used. Here, the detailed method of double-sided scanning does not matter.

Thereafter, it is analyzed whether or not there is an image on the back side of the front side that the user is trying to copy (step S1102).
Next, in step S1103, it is determined whether or not there is an image on the back side. If it is determined that Yes, that is, an image exists on the back side, the process proceeds to step S1104. On the other hand, if it is determined that No, that is, no image exists on the back surface, the process proceeds to step S1105.

In step S1104, the show-through in the show-through prevention process so that the show-through value corresponding to the document paper type specified by the user on the setting screen shown in FIG. Change the value.
On the other hand, in step S1105, since no image exists on the back side, that is, there is no concern of show-through, a value (through setting value) that does not perform the show-through prevention processing is used as a show-through value in the show-through prevention processing. Apply.

After the show-through value is determined by the above method, the show-through prevention process is performed.
The show-through prevention processing method performed by the CPU 103 (show-through prevention processing means) may be any known method as long as the strength of the effect can be determined from the show-through value. For example, the output value may be converted by performing the following equation (4). In Expression (4), x is an input pixel value, y is an output pixel value, f is a show-through value obtained by the above-described method (where f ≠ 0), and B is a predetermined processing coefficient.

[Second Embodiment]
First, FIG. 12 shows another example of the measurement pattern.
Although the measurement pattern shown in FIG. 7 used in the first embodiment includes only gray patches, FIG. 12 includes color patches. In this example, red (Red), green (Green), blue (Blue), cyan (Cyan), magenta (Magenta), yellow (Yellow), and black (Black) are used. Patches having different densities are arranged for each color, and FIG. 12 shows a case where patches of five levels are arranged. Such a measurement pattern is effective for obtaining an appropriate show-through level when the show-through level changes depending on the print color, such as light yellow or light light blue, which is not white. Moreover, as such a measurement pattern, it has an area larger than a certain area composed of a certain color and a certain density, and there are two or more types of measurement areas (density patches) for calculating the show-through value. It is preferable to arrange one or more types of colors for each color. Further, the printer unit 300 (image forming engine) can be used for color matching. In the present embodiment, processing using such a color measurement pattern will be described.

  FIG. 13 shows a flow for determining the show-through value according to the data obtained by reading the measurement pattern with the scanner 200.

  In step S1301, variables used for sequentially processing each color are initialized. Specifically, the counter j is set to 0, and the number of patch colors is set to the variable cl. In addition, since the number of patch colors included in the pattern used in this embodiment is seven, cl = 7.

In step S1302, it is determined whether or not the acquisition of the show-through value for all colors has been completed (if j <cl, the process has not been completed).
The subsequent processing from step S1303 to step S1309 is the same as the processing from step S901 to step S907 shown in FIG. 9, respectively. Therefore, the description is omitted here.

  In step S1310 subsequent to step S1309, after the show-through value f [j] of the j-th patch color in step S1309 is determined, the counter j is incremented in order to perform the process for the next color.

  By repeating steps S1303 to S1309, the show-through value f [j] of each patch color is determined. When these processes are completed, the process proceeds to step S1311 based on the determination in step S1302.

  In step S1311, the show-through value f [j] of each color multiplied by a predetermined weighting factor w [j] is compared with each other, and the color having the maximum value f [j] * w [j] is obtained. Here, j which maximizes f [j] * w [j] is obtained, and is set to k.

  Then, the show-through value f [k] corresponding to the color k obtained in step S1311 is determined as the final show-through value f (step S1312).

  For the default weighting coefficient used in step S1311, for example, a table is prepared in advance as shown in FIG. In the example of FIG. 14, the value of black (K) is considered most important.

[Third Embodiment]
In the present embodiment, a description will be given of a configuration that allows a user to confirm an actual copy sample and perform fine adjustment when registering a show-through value.
FIG. 15 and FIG. 16 are diagrams showing a show-through level registration flow in the present embodiment.

First, a sheet for measuring the show-through level is set in the sheet cassette 302 to prepare for printing a measurement pattern.
In step S1501, the user selects the number of show-through data to be registered. An example of the operation screen at this time is shown in FIG.
In step S1502, a measurement pattern print instruction is issued (the OK button is pressed from the registration screen). An example of the operation screen at this time is shown in FIG. When this instruction is given, the CPU 103 reads the measurement pattern information stored in advance in the HDD 109 and sends a command for outputting the measurement pattern at the printer unit 300.

The printer unit 300 prints the measurement pattern on both sides according to the received command (step S1503).
Thereafter, the process proceeds to step S1504, and the user sets the output measurement pattern on the scanner unit 200 according to the operation screen shown in FIG. 16C, and scans by pressing the “OK” button on the operation screen. To implement.

  In step S1505, the CPU 103 calculates a show-through value by the above-described method based on the read value of the measurement pattern read by the scanner unit 200.

  Next, a show-through prevention process to which the show-through value is applied is performed on the image data scanned in step S1504, and other normal processes at the time of copying are further performed and output by the printer unit 300 (step S1506). ). Until this process is completed, a screen indicating that the process is continuing is displayed as shown in FIG.

  When the output in step S1506 is completed, the user confirms the output result (FIG. 16E) in step S1506. If there is no problem, the user presses the “OK” button on the operation screen (FIG. 16F). . On the other hand, when it is determined that the output result is not expected, the strength of the show-through prevention process is adjusted with the slider on the operation screen (FIG. 16F). Thereafter, when the “sample output” button is pressed, the copy operation from the scan of the original is started again, and a copy output product subjected to the show-through prevention process with the show-through value finely adjusted by the user is generated (FIG. 16 (e)). )). The user confirms the result again.

  Steps S1506 and S1507 (FIGS. 16E and 16F) are repeated, and when the user determines that the adjustment is complete, the “OK” button on the screen of FIG. 16F is pressed. Thereby, the show-through value that has been adjusted is stored in step S1508.

  In step S1509, the user designates an arbitrary registered name. Examples of the operation screen at this time are shown in FIGS. The user can input and specify a registered name from the registered name input screen shown in FIG. When the input is completed, a confirmation screen shown in FIG. 16 (i) is displayed, and a series of processing ends.

[Other Embodiments]
The present invention can also be applied to a system composed of a plurality of devices (for example, a computer, an interface device, a reader, a printer, etc.), or to a device composed of a single device (a multifunction device, a printer, a facsimile device, etc.). It is also possible to do.

  Another object of the present invention is that a computer (or CPU or MPU) of a system or apparatus reads and executes the program code from a storage medium that stores the program code that realizes the procedure of the flowchart shown in the above-described embodiment. Is also achieved. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment. Therefore, the program code and a computer-readable storage medium storing / recording the program code also constitute one aspect of the present invention.

  As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like is used. be able to.

  The functions of the above-described embodiments are realized by a computer executing a read program. The execution of the program includes a case where an OS or the like running on the computer performs part or all of the actual processing based on an instruction of the program.

  Furthermore, the functions of the above-described embodiments can also be realized by a function expansion board inserted into a computer or a function expansion unit connected to a computer. In this case, first, the program read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instructions of the program, the CPU provided in the function expansion board or function expansion unit performs part or all of the actual processing. The functions of the above-described embodiment are also realized by processing by such a function expansion board or function expansion unit.

1 is an external view of a digital multi-functional peripheral suitable as a first embodiment according to the present invention. It is a figure which shows the structure of the controller 100 in the embodiment. It is a figure which shows tile data notionally. It is a block diagram of the scanner image processing part in the embodiment. FIG. 2 is a configuration diagram of a printer image processing unit in the same embodiment. It is a flowchart of a show-through level registration process in the embodiment. It is a figure which shows an example of the pattern for a measurement in the same embodiment. It is an example of an operation screen of a show-through level registration process in the same embodiment. It is a flowchart of a show-through value calculation process in the same embodiment. It is an example of a show-through level setting screen in the same embodiment. It is a flowchart of a show-through prevention process coefficient setting process at the time of copying in the same embodiment. It is a figure which shows an example of the pattern for a measurement in 2nd Embodiment. It is a flowchart of a show-through value calculation process in the same embodiment. It is an example of the table used by the show-through value calculation process in the embodiment. It is a flowchart of the show-through level registration process in 3rd Embodiment. It is an example of an operation screen at the time of show-through level registration processing in the same embodiment.

Explanation of symbols

100 Controller unit 103 CPU
107 RAM
109 HDD
150 Scanner Image Processing Unit 160 Printer Image Processing Unit 200 Scanner Unit 300 Printer Unit 400 Operation Unit

Claims (12)

Image input means for scanning the document and acquiring image data;
Image forming means for forming an image on a recording medium based on image data;
Image data storage means for holding pattern image data for measurement for measuring the back surface image transmission characteristics of the recording medium;
Coordinate storage means for holding the measurement coordinate position of the measurement pattern image data;
Operation means for giving an instruction to measure the back side image transmission characteristics of the recording medium;
A pattern image forming unit for measurement that causes the image forming unit to form a pattern image for measurement on a recording medium based on the pattern image data for measurement;
An image of a predetermined coordinate based on a measurement coordinate position held in the coordinate storage means from image data obtained by scanning the measurement pattern image formed by the measurement pattern image forming means by the image input means. Measurement data acquisition means for acquiring data;
Back image transmission characteristic calculation means for calculating a back image transmission characteristic based on the image data acquired by the measurement data acquisition means;
Backside image transmission characteristic storage means for holding data calculated by the backside image transmission characteristic calculation means;
A show-through prevention processing unit that performs a show-through prevention process according to the back surface image transmission characteristics for the image data input by the image input unit;
An image processing apparatus comprising: The back image transmission characteristic storage means stores two or more types of back image transmission characteristics,
The image processing apparatus according to claim 1, wherein the operation unit receives selection of one type of characteristic to be applied to the show-through prevention processing unit from the two or more types of back surface image transmission characteristics.   The measurement pattern images formed by the measurement pattern image forming unit are formed on both surfaces of a recording medium, and the images formed on the both surfaces are arranged at positions that do not overlap each other with the recording medium interposed therebetween. The image processing apparatus according to claim 1 or 2.   The image processing apparatus according to any one of claims 1 to 3, wherein the measurement pattern image includes one or more types of measurement regions having a certain area or more and having a certain density. .   In the measurement pattern image, a measurement area having a certain area or more constituted by a certain color and a certain density is arranged with one or more densities for every two or more kinds of colors. The image processing apparatus according to claim 1.   6. The image processing apparatus according to claim 5, wherein the back surface image transmission characteristic calculation unit calculates one back surface image transmission characteristic by performing an operation with a predetermined weight for each color of the measurement pattern image.   And an operation unit for instructing execution of the show-through prevention process according to the back image transmission characteristic stored in the back image transmission characteristic storage unit during the copying process of the document, and on the operation screen of the operation unit. The displayed initial value for the show-through prevention process can be changed according to the back side image transmission characteristics, and the setting for the show-through prevention process can be arbitrarily changed from the initial value of the setting. The image processing apparatus according to claim 1, wherein the image processing apparatus can perform the processing.   The measurement pattern image formed by the measurement pattern image forming unit can be applied to other functions of the image processing apparatus, and an instruction to measure the back surface image transmission characteristics of the recording medium. The image processing apparatus according to any one of claims 1 to 7, wherein the other function is simultaneously performed using an operation unit for providing the function. Holding means for holding measurement pattern image data for measuring the back surface image transmission characteristics of the recording medium;
Forming means for forming a measurement pattern image corresponding to the measurement pattern image data on a recording medium in accordance with a user instruction;
A calculation unit that reads the measurement pattern image formed by the forming unit and calculates a back surface image transmission characteristic;
Storage means for storing the back surface image transmission characteristics calculated by the calculation means;
Processing means for performing a show-through prevention process on the input image according to the back surface image transmission characteristic stored by the storage means;
An image processing apparatus comprising: In an image processing apparatus, an image processing method executed by the control means,
An image data storage step of storing measurement pattern image data for measuring the back surface image transmission characteristics of the recording medium in the storage device of the image processing device;
A coordinate storage step of storing a measurement coordinate position of the measurement pattern image data in a storage device of the image processing device;
An operation step of receiving an input of an instruction to measure the back side image transmission characteristic of the recording medium;
A measurement pattern image forming step of forming a measurement pattern image on a recording medium based on the measurement pattern image data;
Based on the measurement coordinate position stored in the storage device of the image processing device by the coordinate storage step from the image data acquired by scanning the measurement pattern image formed by the measurement pattern image formation step, the predetermined coordinates A measurement data acquisition process for acquiring image data of
A back side image transmission characteristic calculating step for calculating a back side image transmission characteristic based on the image data acquired by the measurement data acquiring step;
A back image transmission characteristic storage step of storing data calculated by the back image transmission characteristic calculation step in a storage device of the image processing device;
A show-through prevention processing step of performing a show-through prevention process according to the back side image transmission characteristics for the image data input by the image input step of scanning the original to obtain image data;
An image processing method comprising: In an image processing apparatus, an image processing method executed by the control means,
A holding process for holding pattern image data for measurement for measuring the backside image transmission characteristics of the recording medium;
Forming a measurement pattern image according to the measurement pattern image data on a recording medium in accordance with a user instruction;
A calculation step of reading the measurement pattern image formed in the formation step and calculating a back surface image transmission characteristic;
A storage step of storing the back surface image transmission characteristics calculated in the calculation step;
A processing step of performing a show-through prevention process on the input image according to the back image transmission characteristics stored in the storage step;
An image processing method comprising: A program executed in an image processing apparatus including a control unit and a storage unit,
An image data storage step of storing measurement pattern image data for measuring the back surface image transmission characteristics of the recording medium in the storage device of the image processing device;
A coordinate storage step of storing the measurement coordinate position of the measurement pattern image data in the storage device;
An operation step of receiving an input of an instruction to measure the back side image transmission characteristic of the recording medium;
A measurement pattern image forming step of forming a measurement pattern image on a recording medium based on the measurement pattern image data;
From the image data obtained by scanning the measurement pattern formed by the measurement pattern image forming step, image data of predetermined coordinates is obtained based on the measurement coordinate position stored in the storage device by the coordinate storage step. A measurement data acquisition process to be acquired;
A back side image transmission characteristic calculating step for calculating a back side image transmission characteristic based on the image data acquired by the measurement data acquiring step;
A back side image transmission characteristic storage step of storing the data calculated by the back side image transmission characteristic calculation step in the storage device;
A show-through prevention processing step of performing a show-through prevention process according to the back side image transmission characteristics for the image data input by the image input step of scanning the original to obtain image data;
The program for making the said control means perform each process including these.

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