JP2020174315A - Image processing device and control program therefor - Google Patents

Abstract

To provide an image processing device and a control program therefor that can suppress an increase in manufacturing cost.SOLUTION: An image processing device includes a background gradation value detection unit 621 that detects the level of each RGB color of the background of an original on the basis of image data of each color of R (red), G (green), and B (blue) of the original, level determination means that determines whether the R color level of a specific pixel in the original is a predetermined value on the basis of the R color image data, a hue determination unit 625 that determines whether the hue of the specific pixel is R color on the basis of the image data of each RGB color, a low saturation determination unit 628 that determines whether the saturation of the specific pixel is within a predetermined range on the basis of the image data of each RGB color, and a selection unit 631 that replaces the level of each RGB color of the specific pixel with the level of each RGB color of the background when the R color level of the specific pixel is a predetermined value, the specific pixel is R, and the saturation of the specific pixel is within a predetermined range.SELECTED DRAWING: Figure 8

Description

The present invention relates to an image processing device and a control program for the image processing device. More specifically, the present invention relates to an image processing apparatus and a control program of the image processing apparatus capable of suppressing an increase in manufacturing cost.

In recent years, writing instruments (friction (registered trademark), etc.) using heat-erasable ink, which is an ink whose color can be erased by heating, have been proposed.

When a user of a writing instrument with heat-erasable ink wants to erase the characters drawn on the original, the characters are rubbed with a special eraser. As a result, frictional heat is generated between the original material and the eraser, and the generated frictional heat makes the heat-erasable ink on the original material transparent. As a result, although the heat-erasable ink on the original is not actually removed, the drawn characters are erased (invisible). However, when an image of a document containing characters of erased heat-erasable ink is read by a full-color image reader, the erased characters are reproduced thinly in the obtained image data.

FIG. 16 is a diagram illustrating a principle in which erased characters are thinly reproduced in image data. FIG. 16A is a graph showing the detectable wavelength range of each of the line sensors for R (red), G (green) and B (blue) colors of the full-color image reader. FIG. 16B is a diagram schematically showing the received light intensity from the character portion drawn with the blue heat-erasable ink IK. FIG. 16 (c) is a diagram schematically showing the intensity of received light from the erased marks of characters drawn with the blue heat-erasable ink IK. FIG. 17 is a diagram showing the positional relationship between the line sensor 331 and the blue heat-erasable ink IK.

With reference to FIGS. 16 (a) and 17, the full-color image reader includes a light source 325, lenses 329 and 330, and a line sensor 331. The line sensor 331 includes a line sensor for each color of RGB. The light emitted from the light source 325 is reflected by the document, passes through the lenses 329 and 330, and is received by the line sensor 331. The line sensor 331 outputs a voltage corresponding to the received light intensity of each RGB color. As a result, the full-color image reader detects each of the R color gradation value, the G color gradation value, and the B color gradation value of each of the plurality of pixels constituting the image of the original.

At this time, since the line sensor for R color detects not only R color light (light in the visible light wavelength region) but also infrared light (light in the infrared wavelength region), the R color light and infrared light. Outputs a voltage according to the light reception intensity.

By the way, with reference to FIGS. 16 (b) and 17, the heat-erasable ink has a property of being excited by visible light and emitting infrared light regardless of its temperature (whether or not it is erased). There is. Therefore, for example, when an image of a document containing characters drawn with blue heat-erasable ink IK is read, the reflected light from the character portion received by the line sensor 331 includes blue light and infrared light. It has been. As a result, the gradation value of the pixel of the character portion in the image data output from the full-color image reader becomes high in the R color as well as the B color.

With reference to FIGS. 16 (c) and 17, the properties of the heat-erasable ink that is excited by visible light and emits infrared light are after the characters have been erased (after the heat-erasable ink has become transparent). Even if there is, it will not be lost. Therefore, when an image of a document including erasure marks of characters drawn with the heat-erasable ink IK is read, infrared light is included in the reflected light from the character portion received by the line sensor 331. .. As a result, the B color gradation value of the pixel of the erasure mark portion of the character in the image data output from the full-color image reader becomes zero, while the R color gradation value becomes high. The R color is reproduced lightly on the erased marks in the image data.

The conventional image reading device is disclosed in, for example, Patent Document 1 below. The following Patent Document 1 includes a light emission control means for controlling the lighting of three-color LEDs (Light Emitting Diodes) that illuminate a document, and a plurality of sensors that receive the reflected light from the document with different spectral sensitivity characteristics. An image reader is disclosed. This image reader is an invisible light generating pixel from the difference between the red image data of the first image data acquired by turning on only the green LED and the second image data acquired by turning on the LEDs of all colors. It is provided with an analysis means for specifying the above and a data correction means for correcting the R color image data of the invisible light generating pixel specified from the difference data.

Japanese Unexamined Patent Publication No. 2004-260457

As a method of avoiding the situation where the R color is thinly reproduced in the erased mark portion in the scanned image, a method of providing an infrared cut filter FT (FIG. 17) between the lenses 329 and 330 and the line sensor 331 can be considered. .. However, this method has a problem that the manufacturing cost increases because a configuration called an infrared cut filter FT is further required. In particular, when the line sensor 331 has a configuration in which a plurality of line sensors are arranged in the main scanning direction as in CIS (Contact Image Sensor), the infrared cut filter is unevenly arranged in the main scanning direction (coating unevenness). ) Must be made sufficiently large so that the manufacturing cost has increased remarkably. Since the infrared light is generated from the heat erasable ink IK, it was not possible to provide an infrared cut filter FT between the light source 325 and the heat erasable ink IK.

Further, the technique of Patent Document 1 has a problem that the manufacturing cost increases because a three-color LED is required as a light source.

The present invention is for solving the above problems, and an object of the present invention is to provide an image processing device and a control program for the image processing device capable of suppressing an increase in manufacturing cost.

The image processing apparatus according to one aspect of the present invention detects the level of each red, green, and blue color of the background of the original based on the image acquisition means for acquiring the image data of each red, green, and blue color of the original, and the image data of each red, green, and blue color. Based on the background level detecting means, the level determining means for determining whether or not the red level at a specific position in the document is a predetermined value based on the red image data, and the image data of each color of red, green, and blue. , Determines whether or not the saturation of a specific position is within a predetermined range based on the hue determining means for determining whether or not the hue of a specific position is red and the image data of each color of red, green, and blue. The saturation discriminating means and the level discriminating means discriminate that the level of red at a specific position is a predetermined value, and the hue discriminating means discriminates that the hue at a specific position is red, and a specific When the saturation determination means determines that the saturation of the position is within a predetermined range, it is provided with a replacement means for replacing the level of each color of red, green, and blue at a specific position with the level of each color of red, green, and blue of the background.

In the above image processing apparatus, preferably, the image acquisition means is an irradiation means for irradiating the document with light, a light receiving means for receiving the reflected light from the document, and an image for generating image data of each color of red, green, and blue based on the reflected light. The generation means includes an image generation means for generating red image data based on the light in the red wavelength region and the infrared wavelength region included in the reflected light.

In the above image processing apparatus, preferably, the level determining means determines whether or not the red level at a specific position is close to the red level of the background, and the replacement means has the red level at the specific position as the background. It is determined by the level discrimination means that it is near the red level of the above, and it is determined by the hue discrimination means that the red level at a specific position is near the red level of the background, and the color at a specific position is colored. When the saturation determination means determines that the degree is within a predetermined range, the level of each color of red, green, and blue at a specific position in the image data of each color of red, green, and blue is replaced with the level of each color of red, green, and blue at the base position.

In the above image processing apparatus, preferably, the level discriminating means is used when the difference between the red level at the specific position and the red level of the background is within ± 1% of the red level of the background. Determine that the red level is near the underlying red level.

In the above image processing apparatus, preferably, the level determining means determines whether or not the red level at a specific position is the maximum level of the detected value, and the replacement means determines whether the red level at the specific position is the detected value. The level determination means determines that the level is the maximum, and the hue determination means determines that the red level at a specific position is close to the red level of the background, and the saturation at the specific position is predetermined. When it is determined by the saturation determination means that it is within the range, the level of each color of red, green, and blue at a specific position in the image data of each color of red, green, and blue is replaced with the level of each color of red, green, and blue at the base position.

In the above image processing apparatus, preferably, the level discriminating means includes a first discriminating means for discriminating whether or not the red level at a specific position is in the vicinity of the red level of the background, and the red level at the specific position. Includes a second determination means for determining whether or not is the maximum level of the detected value, and a selection means for selecting one of the first and second determination means, and the replacement means is a selection means. When the first level discriminating means is selected, the first level discriminating means determines that the red level at a specific position is close to the red level of the background, and the hue at the specific position is red. When it is determined by the hue discrimination means and the saturation at a specific position is within a predetermined range by the saturation discrimination means, the level of each color of red, green, and blue at the specific position is set as the background. Replaced with the level of each color of red, green, and blue at the position, and the replacement means is the second level when the red level at a specific position is the maximum level of the detection value when the second level determination means is selected by the selection means. When discriminating by the discriminating means, determining that the hue at a specific position is red by the hue discriminating means, and determining that the saturation at the specific position is within a predetermined range by the saturation discriminating means. Replaces the level of each color of red, green, and blue at a specific position in the image data of each color of red, green, and blue with the level of each color of red, green, and blue at the base position.

The image processing apparatus preferably further includes a receiving means for receiving an input for setting the type of ink contained in the document, and the selecting means selects based on the setting received by the receiving means.

In the above image processing apparatus, preferably, the background level detecting means is a histogram creating means for creating a histogram showing the distribution of brightness in the image of the original based on the image data of each color of red, green, and blue, and the brightness that becomes the peak in the histogram. It includes a level extraction means for extracting the level of each color of red, green, and blue at the position in the original from the image data of each color of red, green, and blue, and detecting the level of each of the extracted red, green, and blue as the level of each color of red, green, and blue of the background.

In the above image processing apparatus, preferably, the red level at a specific position in the red image data is defined as the level SR, the green level at the specific position in the green image data is defined as the level SG, and the specific position in the blue image data. When the level SR, level SG, and level SB satisfy the condition of | SR-SG |> | SG-SB |, the hue discriminating means has a hue at a specific position. Determined to be red.

In the above image processing apparatus, preferably, the saturation determination means determines whether or not the saturation at a specific position is within a range larger than the saturation of the base and smaller than the saturation of red.

In the above image processing apparatus, preferably, the red level at a specific position in the red image data is defined as the level SR, the green level at the specific position in the green image data is defined as the level SG, and the specific position in the blue image data. The blue level of is the level SB, the maximum level of the level SR, level SG, and level SB is the maximum level Max (SR, SG, SB), and the minimum level of the level SR, level SG, and level SB. When is set to the minimum level Mix (SR, SG, SB), the saturation determination means sets the saturation CF at a specific position to CF = Max (SR, SG, SB) -Mix (SR, SG, SB). Calculate using the formula.

In the above image processing apparatus, preferably, the replacement means corrects so that the gamma value of the level of each blue-green color at a specific position in the image data of each blue-green color matches the gamma value of the level of each blue-green color of the background.

The control program of the image processing apparatus according to the other aspects of the present invention has an image acquisition step of acquiring image data of each red, green, and blue color of the original, and a level of each red, green, and blue color of the background of the original based on the image data of each red, green, and blue color. A background level detection step for detecting red, a level determination step for determining whether or not the red level at a specific position in a document is a predetermined value based on red image data, and image data for each color of red, green, and blue. Based on the hue determination step for determining whether or not the hue at a specific position is red, and whether or not the saturation at a specific position is within a predetermined range based on the image data of each color of red, green, and blue. The saturation determination step for determining and the level determination step determines that the red level at a specific position is a predetermined value, and the hue determination step determines that the hue at a specific position is red. In addition, when the saturation determination step determines that the saturation at a specific position is within a predetermined range, the replacement step of replacing the level of each red, green, and blue color at the specific position with the level of each color of the underlying red, green, and blue is used. It is intended to be executed by a computer.

According to the present invention, it is possible to provide an image processing device and a control program for the image processing device that can suppress an increase in manufacturing cost.

It is a figure which shows the appearance of the image forming apparatus 1 in one Embodiment of this invention. It is a block diagram which shows the structure of the image forming apparatus 1 in one Embodiment of this invention. It is sectional drawing which shows the structure of the image reading unit 31. It is a block diagram explaining the general operation of the image reading unit 31. When an image of a document containing characters drawn with red heat-erasable ink (non-fluorescent color) on a white background is read by the image reading unit 31, the image output from the image reading unit 31 It is a figure which shows the analysis result. When an image of a document containing characters drawn with red heat-erasable ink (fluorescent color) on a white background is read by the image reading unit 31, the image output from the image reading unit 31 It is a figure which shows the analysis result. FIG. 5 is a block diagram illustrating an outline of processing performed by the image processing unit 6 when printing image data generated by the image reading unit 31 (when copying a document) in one embodiment of the present invention. It is a figure which shows the circuit structure of the ink partial correction processing part 62 in one Embodiment of this invention. It is a figure explaining the method of detecting the gradation value of each RGB color of the background of a document performed by the background gradation value detection unit 621 in one Embodiment of this invention. It is a figure explaining the discrimination method performed by the R color neighborhood discrimination unit 622 in one Embodiment of this invention. 6 is a histogram showing the relationship between the R color gradation value of the pixel of the trace portion where the characters drawn with the heat-erasable ink (non-fluorescent color) are erased and the R color gradation value of the background of the original. It is a figure which shows an example of the screen displayed on the operation display unit 33. It is a figure explaining the gamma correction with respect to the gradation value SR, SG, and SB of each RGB color of the extracted pixel. This is the first part of the flowchart showing the processing executed by the ink partial correction processing unit 62 in one embodiment of the present invention. This is the second part of the flowchart showing the processing executed by the ink partial correction processing unit 62 in one embodiment of the present invention. It is a figure explaining the principle that erased characters are reproduced thinly in image data. It is a figure which shows the positional relationship between a line sensor 331 and a blue heat-erasable ink IK.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In the following embodiment, a case where the image processing device is an MFP (Multifunction Peripheral) will be described. The MFP is an electrophotographic image forming apparatus having a scanner function, a facsimile function, a copying function, a printer function, a data communication function, and a server function. In addition to the case where the image processing device is an MFP, it may be a scanner, a copying machine, or the like, or may be a PC (Personal Computer), a mobile phone, a smartphone, or the like.

[Configuration of image forming apparatus and basic reading operation]

First, the configuration of the image forming apparatus according to the present embodiment will be described.

FIG. 1 is a diagram showing the appearance of the image forming apparatus 1 according to the embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of an image forming apparatus 1 according to an embodiment of the present invention.

With reference to FIGS. 1 and 2, the image forming apparatus 1 in the present embodiment includes a main controller 10, an image reading unit 31 (an example of an image acquisition means), a printer engine unit 32, and an operation display unit 33 ( An example of a reception means), a communication unit 34, a voice processing unit 35, a voice input unit 36, and a voice output unit 37 are provided. The main controller 100, the image reading unit 31, the printer engine unit 32, the operation display unit 33, the communication unit 34, and the voice processing unit 35 are each connected to each other.

The main controller 10 controls the operation of the entire image forming apparatus 1. The main controller 10 includes a CPU (Central Processing Unit) 2, a ROM (Read Only Memory) 3, a memory 4, an HDD (Hard Disk Drive) 5, and an image processing unit (ASIC (Application Specific Integrated Circuit) 6). Includes.

The CPU 2 controls the operation of the entire image forming apparatus 1. The CPU 2 executes the program stored in the ROM 3.

The ROM 3 stores a control program executed by the CPU 2 and various parameters.

The memory 4 is a memory for the work of the CPU 2, and temporarily stores data, image data, and the like necessary for the CPU 2 to operate the control program.

The HDD 5 is an auxiliary storage device that stores various types of information.

The image processing unit 6 performs processing on the image data generated by the image reading unit 31 and the like.

The image reading unit 31 reads the image of the original and generates (acquires) image data of each RGB color.

The printer engine unit 32 performs a print job of forming an image on paper or the like based on the image data. The printer engine unit 32 is roughly composed of a toner image forming unit, a fixing device, a paper conveying unit, and the like. The printer engine unit 32 forms an image on paper by, for example, an electrophotographic method. The toner image forming unit forms an image on paper. The toner image forming unit is composed of a developing device that develops a toner image, a photoconductor on which a toner image is formed, a transfer unit that transfers an image from the photoconductor to paper, and the like. The fixing device has a heating roller and a pressure roller. The fixing device conveys the paper on which the toner image is formed between the heating roller and the pressure roller while sandwiching the paper, and heats and pressurizes the paper. As a result, the fixing device melts the toner adhering to the paper and fixes it on the paper to form an image on the paper. The paper transport unit is composed of a paper feed roller, a transport roller, a motor for driving them, and the like. The paper transport unit feeds the paper from the paper feed cassette and transports the paper inside the housing of the image forming apparatus 1. In addition, the paper transport unit discharges the paper on which the image is formed from the housing of the image forming apparatus 1 to the paper output tray 38.

The operation display unit 33 receives various operations and displays various information.

The communication unit 34 communicates with an external device.

Under the control of the main controller 10, the voice processing unit 35 outputs necessary voice from the voice output unit 37, changes the voice input from the voice input unit 36 into a predetermined format, and transmits the voice to the main controller 10. ..

Each of the voice input unit 36 and the voice output unit 37 is connected to the voice processing unit 35. The voice input unit 36 accepts voice input. The audio output unit 37 outputs audio.

The main controller 10 executes an image reading function (scan), an image forming function (printing), and the like based on operation instructions from the operation display unit 33 and the communication unit 34. Further, when the user inputs a voice including a specific operation instruction to the voice input unit 36, the voice processing unit 35 recognizes the voice, converts the recognized voice information into a predetermined format, and main controller. Send to 10. Based on the information received from the voice processing unit 35, the main controller 10 executes various functions in the same manner as the operation instructions from the operation display unit 33 and the communication unit 34. Further, when it is detected that it is necessary to generate a voice for the user, the main controller 10 emits a voice in the voice output unit 37 via the voice processing unit 35.

In the above configuration, the voice processing unit 35 is connected to the main controller 10 via an interface, but a part or the whole of the voice processing unit 35 may be included inside the main controller 10. The voice processing unit 35 and the voice input unit 36 may be integrated. Further, the communication between the main controller 10 and the voice processing unit 35 may be performed via a network such as LAN (Local Area Network) or WAN (Wide Area Network).

FIG. 3 is a cross-sectional view showing the configuration of the image reading unit 31. FIG. 4 is a block diagram illustrating a general operation of the image reading unit 31.

With reference to FIG. 3, the image reading unit 31 includes an ADF (Auto Lens Feeder) 310, a contact glass 321, a platen glass 322, a wire 323, a slider 324, a light source 325 (an example of a light receiving means), and the like. It includes mirrors 326 and 327, a motor 328, lenses 329 and 330, and a line sensor 331 (an example of light receiving means).

The image reading unit 31 reads an image of a document arranged on the document tray 311 and conveyed by the ADF 310. Further, the image reading unit 31 reads an image of a document arranged on the platen glass 322.

The ADF 310 is provided above the housing 31a of the image reading unit 31. The ADF 310 conveys the originals arranged in the original tray 311 to the original reading position P1 along the conveying path, and then ejects the originals to the paper output tray 312.

The contact glass 321 closes the slit 321a provided on the upper surface of the housing 31a, and faces a part of the document transport path exposed on the bottom surface of the ADF 310. The platen glass 322 closes the slit 322a provided on the upper surface of the housing 31a.

Inside the housing 31a, a wire 323, a slider 324, a light source 325, mirrors 326 and 327, a motor 328, lenses 329 and 330, and a line sensor 331 are provided. A slider 324 is connected to the wire 323. The slider 324 is equipped with a light source 325 and mirrors 326 and 327. The wire 323 rotates according to the rotation of the motor 328.

The line sensor 331 includes a line sensor 331R for R color composed of a plurality of light receiving elements arranged in the main scanning direction, and a line sensor 331R for G color composed of a plurality of light receiving elements arranged in the main scanning direction. A line sensor 331B for B color composed of a plurality of light receiving elements for B color arranged in the main scanning direction is included. Each of the line sensors 331R, 331G, and 331B outputs an electric signal corresponding to the received light intensity of each of the R color, the G color, and the B color.

When the image reading unit 31 reads an image of a document conveyed by the ADF 310, the light source 325 irradiates the surface of the document conveyed by the ADF 310 and passing through the document reading position P1 through the contact glass 321. The line sensor 331 receives the reflected light.

When the image reading unit 31 reads an image of a document arranged on the platen glass 322, the motor 328 rotates in the direction indicated by the arrow a or the direction indicated by the arrow b, so that the platen glass 322 is directly under the contact glass 321. The slider 324 connected to the wire 323 is moved to the right end in FIG. The light source 325 irradiates the surface of the document arranged on the platen glass 322 with light through the platen glass 322 while the slider 324 is moving. The reflected light from the document passes through the platen glass 322, is reflected by the mirrors 326 and 327, and is converged by the lenses 329 and 330. The line sensor 331 receives the converged reflected light.

The intensity of the reflected light received by the line sensor 331 changes according to the color of the surface of the document (more accurately, the light reflectance of the surface). Therefore, the electric signal output from the line sensor 331 represents an image displayed on the surface of the document.

With reference to FIG. 4, the image reading unit 31 further includes a driving unit 41, a light emitting unit 42, and an AD conversion unit 43 (an example of an image generation means).

When the operation display unit 33 receives an execution instruction for reading an image of a document arranged on the platen glass 322, the CPU 2 issues a drive command to the drive unit 41 and a light emission command to the light emitting unit 42. Upon receiving the drive command, the drive unit 41 rotates the motor 328 to move the slider 324 in the sub-scanning direction (horizontal direction in FIG. 3). Upon receiving a light emission command, the light emitting unit 42 causes the moving light source 325 to emit light by the slider 324. The light from the light source 325 incident on the document arranged on the platen glass 322. The line sensor 331 receives the reflected light from the document and outputs the light according to the light receiving intensity of each color of RGB. As a result, the line sensor 331 reads the image of the original. The AD conversion unit 43 converts the electric signal output from the line sensor 331 into digital data to generate image data of each RGB color, and outputs the image data of each RGB color to the image processing unit 6.

When the CPU 2 detects that the reading of the original image has been completed, the CPU 2 notifies the driving unit 41 and the light emitting unit 42 of the completion of reading. Upon receiving this notification, the drive unit 41 returns the slider 324 to the home sensor position. Upon receiving this notification, the light emitting unit 42 turns off the light source 325.

Here, each of the plurality of light receiving elements constituting the line sensor 331R detects not only R color light (light in the R color wavelength region) but also infrared light (light in the infrared wavelength region), and the R color. It outputs an electric signal according to the received light intensity of the light and infrared light. Therefore, among the image data of each RGB color generated by the image reading unit 31, the R color image data is generated based on the light in the R color wavelength region and the infrared wavelength region included in the reflected light.

[Summary of detection method for erased marks of heat-erasable ink]

FIG. 5 shows an image of a document containing characters drawn with R-color heat-erasable ink (non-fluorescent color) on a white background when the image reading unit 31 reads the image of the original. It is a figure which shows the analysis result of the output image.

With reference to FIG. 5, the inventor of the present application prepares a manuscript containing characters drawn with R color heat erasable ink (non-fluorescent color) on a white background, and erases the heat erasable ink. The image of the original was read by the image reading unit 31 before and after, and the image output from the image reading unit 31 was analyzed. Specifically, there are pixels before erasing (“ink before erasing” in FIG. 5) in a portion where heat erasable ink (non-fluorescent color) exists, and heat erasable ink (non-fluorescent color). The pixel after erasing the portion (“ink portion after erasing” in FIG. 5) and the background pixel of the document (“base portion” in FIG. 5) are extracted from the image, and the R color gradation value of the extracted pixel is used. , The relationship between the difference between the R color gradation value and the G color gradation value (| RG |) (FIG. 5 (a)), the R color gradation value of the extracted pixel, and the G color gradation value. The relationship between the difference between the B color gradation value and the B color gradation value (| GB |) (FIG. 5 (b)) and the relationship between the R color gradation value and the saturation of the extracted pixel (FIG. 5 (c)). I investigated.

In addition, R color gradation value (an example of a red level), G color gradation value (an example of a green level), and B color gradation value (an example of a blue level) (here, all gradation values are used. (It is assumed that the value is in the range of 0 to 255) is calculated based on the image data output from the image reading unit 31. The hue and saturation are calculated by substituting each of the R color gradation value, the G color gradation value, and the B color gradation value into a predetermined formula.

As a result, it was found that the pixels before erasing (“ink before erasing” in FIG. 5) in the portion where the heat erasable ink (non-fluorescent color) is present have the following features X1 to X3. ..

Feature X1: The R color gradation value differs depending on the color of the heat-erasable ink.

Feature X2: Hues differ from each other depending on the color of the heat-erasable ink.

Feature X3: Saturation is high regardless of the color of the heat-erasable ink.

On the other hand, it was found that the erased pixels (“erased ink portion” in FIG. 5) of the portion where the heat-erasable ink (non-fluorescent color) is present have the following features Y1 to Y3.

Feature Y1: The R color gradation value is equivalent to the R color gradation value of the base regardless of the color of the heat-erasable ink (specifically, the difference from the R color gradation value of the base is the R of the base. It is within the range E1 of ± 1% of the color gradation value) (see FIGS. 5 (a) and 5 (b)).

Feature Y2: The hue is an R color system (| RG |> | GB |) regardless of the color of the heat-erasable ink (see FIGS. 5 (a) and 5 (b)).

Feature Y3: Saturation is lower (than red saturation) regardless of the color of the heat-erasable ink. However, it is higher than the saturation of the base (see FIG. 5 (c)).

The reason why the red saturation (middle triangle in FIG. 5C) is high in FIG. 5C is that the light emitted from the light source 325 has a peak in a predetermined wavelength region of the visible light region. Is presumed to be.

Therefore, in the present embodiment, in the image output from the image reading unit 31, the portion (pixel) satisfying all of the above features Y1, Y2, and Y3 is regarded as an erasing mark portion of the heat erasable ink that is not a fluorescent color. Detected.

FIG. 6 is output from the image reading unit 31 when an image of a document containing characters drawn with red heat-erasable ink (fluorescent color) on a white background is read by the image reading unit 31. It is a figure which shows the analysis result of the said image.

With reference to FIG. 6, the inventor of the present application prepares a manuscript containing characters drawn with heat-erasable ink (fluorescent color) of each RGB color on a white background, and erases the heat-erasable ink. The image of the original was read by the image reading unit 31 before and after, and the image output from the image reading unit 31 was analyzed. Specifically, there are pixels before erasing (“ink before erasing” in FIG. 6) in a portion where heat erasable ink (fluorescent color) exists, and heat erasing ink (fluorescent color). The pixel after erasing the portion (“ink portion after erasing” in FIG. 6) and the background pixel of the document (“base portion” in FIG. 6) are extracted from the image, and the R color gradation value of the extracted pixel is used. The relationship with saturation was investigated.

As a result, it was found that the pixels before erasing (“ink portion before erasing” in FIG. 6) in the portion where the heat erasable ink (fluorescent color) is present have the above-mentioned features X1 to X3.

On the other hand, it was found that the erased pixels (“erased ink portion” in FIG. 6) of the portion where the heat-erasable ink (fluorescent color) is present have the following features Z1 to Z3.

Feature Z1: The R color gradation value is the maximum value (an example of the maximum level of the detected value, 255 in this case) regardless of the color of the heat-erasable ink.

Feature Z2: The hue is an R color system (| RG |> | GB |) regardless of the color of the heat-erasable ink.

Feature Z3: Saturation is lower (than R color saturation) regardless of the color of the heat-erasable ink. However, it is higher than the saturation of the base.

The maximum value of the R color gradation value in the feature Z1 is that the analog output value (output value from the line sensor 331R) before conversion by the AD conversion unit 43 regarding the R color gradation value is the line sensor 331R. It is presumed that this is because the upper limit of the sensitivity of is exceeded.

Therefore, in the present embodiment, in the image output from the image reading unit 31, the portion (pixel) satisfying all of the above features Z1, Z2, and Z3 is used as the erase mark portion of the fluorescent color heat erasable ink. Detected.

It is presumed that the reason why the erased pixels in the portion where the heat-erasable ink is present has the above-mentioned characteristics is as follows. Generally, the heat-erasable ink contains a dye such as a leuco dye, a color developer, and a discoloration temperature adjuster. When the heat-erasable ink is below a predetermined temperature (the temperature specified by the discoloration temperature adjuster), the dye and the color developer are chemically bonded, thereby producing a color according to the type of dye. To do. When the heat-erasable ink is heated above a predetermined temperature (temperature specified by the discoloration temperature adjuster), the color developer breaks the bond with the dye and binds with the discoloration temperature adjuster. As a result, the color of the dye is eliminated. Dyes have the property of emitting light with wavelengths in the infrared region, regardless of temperature. Therefore, even when the heat-erasable ink is heated to a predetermined temperature or higher and the color of the dye disappears, the dye emits light having a wavelength in the infrared region.

[Outline of processing performed by the image processing device]

FIG. 7 is a block diagram illustrating an outline of processing performed by the image processing unit 6 when printing image data generated by the image reading unit 31 (when copying a document) in one embodiment of the present invention. Is.

With reference to FIG. 7, the image processing unit 6 includes an ASIC 61 which is a surface scanner image processing ASIC, an ink partial correction processing unit 62, an ASIC 63 which is a scanner image processing ASIC, an ASIC 64 which is a controller ASIC, and a printer image. Includes ASIC 65, which is a processing ASIC.

The image data of each RGB color input from the image reading unit 31 is first processed by the ASIC 61. The ASIC 61 is an image caused by the difference in physical distance between the surface shading correction for correcting the white level of the background of the image data for the image data of each RGB color, the line sensors 331R, 331G, and 331B of each RGB color. Interline correction for correcting the deviation of the image, and chromatic aberration correction for correcting the distortion of the image caused by the aberration of the optical system included in the image reading unit 31 are performed. The ASIC 61 transmits the processed image data of each RGB color to the ink partial correction processing unit 62.

The ink portion correction processing unit 62 detects the portion of the erase mark of the heat-erasable ink from the received image data of each RGB color, and corrects the detected portion to the background color of the original. The processing performed by the ink partial correction processing unit 62 will be described later. The ink partial correction processing unit 62 transmits the processed image data of each RGB color to the ASIC 63.

The ASIC 63 has a resolution conversion process for enlarging or reducing an image at a required magnification, a background skipping process for whitening excess background color when the original is recycled paper, etc., and image data in a halftone dot area, a character area, and an image. Area discrimination processing for classifying into areas, conversion processing for converting image data of each RGB color into image data for each color of YMCK, character edge correction for correcting the character area, error diffusion processing for smoothing the image, etc. .. The ASIC 63 transmits the processed image data of each color of YMCK and the attribute signal SN to the ASIC 64.

The ASIC 64 performs compression processing on the image data and the attribute signal SN of each color of YMCK, and stores the data and the attribute signal SN after the compression processing in the memory 4. Further, the ASIC 64 reads the data of each color of YMCK and the attribute signal SN from the memory 4 by performing the decompression processing on the data stored in the memory 4. The ASIC 64 transmits the processed image data of each color of YMCK and the attribute signal SN to the ASIC 65.

The ASIC65 includes image correction processing such as edge enhancement and smoothing, processing for synthesizing a tint block image for copy protection, screen processing for emphasizing gradation changes, and delay between PCs for correcting the timing deviation of printing each color of YMCK on paper. Control processing, processing for adjusting print strength (PWM + synchronous IC), and the like are performed as necessary. After processing, the ASIC 65 transmits the image data of each color of YMCK and the attribute signal SN to the printer engine unit 32.

[Processing performed by the ink partial correction processing unit]

FIG. 8 is a diagram showing a circuit configuration of the ink partial correction processing unit 62 according to the embodiment of the present invention.

With reference to FIG. 8, the ink portion correction processing unit 62 includes a background gradation value detection unit 621 (an example of a background level detecting means), an R color neighborhood discrimination unit 622 (an example of a level discrimination means), and an R color maximum. Select the value discrimination unit 623 (an example of the level discrimination means), the saturation detection unit 624 (an example of the saturation discrimination means), the hue discrimination unit 625 (an example of the hue discrimination means), and the background saturation detection unit 626. A unit 627, a low saturation determination unit 628, an AND type circuit 629, a gradation value replacement unit 630, and a selection unit 631 (an example of replacement means) are included.

The background gradation value detection unit 621 is based on the image data of each RGB color input from the image reading unit 31 (hereinafter, the image data input from the image reading unit 31 may be referred to as input image data). The gradation values UR, UG, and UB of each of the RGB colors of the background are detected.

FIG. 9 is a diagram illustrating a method of detecting gradation values of each RGB color of the background of a document by the background gradation value detecting unit 621 in one embodiment of the present invention.

With reference to FIGS. 8 and 9, the background gradation value detection unit 621 calculates the brightness V of each pixel in the input image data and creates a histogram showing the distribution of the brightness in the image of the original. The brightness V of a pixel is calculated as an average value of the R color gradation value, the G color gradation value, and the B color gradation value of the pixel, for example, as shown in the following formula (1).

V = average (R, G, B) ... (1)

Subsequently, the background gradation value detection unit 621 detects the maximum brightness (here, the value PK1) among the peak brightnesses in the histogram as the background brightness. The background gradation value detection unit 621 detects the same value as the detected brightness value PK1 as the gradation values UR, UG, and UB of each RGB color of the background of the document.

FIG. 10 is a diagram illustrating a discrimination method performed by the R color neighborhood discriminating unit 622 in one embodiment of the present invention.

With reference to FIGS. 8 and 10, the R color neighborhood determination unit 622 extracts pixels in the document in the input image data one by one, and the R color gradation value SR of the extracted pixels is the background gradation. It is determined whether or not it is in the vicinity of the R color gradation value UR of the background detected by the value detection unit 621. The R color neighborhood determination unit 622 outputs "1" to the selection unit 627 when it determines that the R color gradation value SR of the extracted pixel is near the R color gradation value UR of the background. When the R color neighborhood determination unit 622 determines that the R color gradation value SR of the extracted pixel is not in the vicinity of the base R color gradation value UR, the R color neighborhood determination unit 622 outputs “0” to the selection unit 627.

In the R color proximity discrimination unit 622, the difference between the R color gradation value SR of the extracted pixel and the R color gradation value UR of the background is within ± 1% of the R color gradation value UR of the background (in other words, , The R color gradation value SR of the extracted pixel is within the range of the range RG1), it is determined that the R color gradation value SR of the extracted pixel is in the vicinity of the R color gradation value UR of the background. On the other hand, in the R color neighborhood discrimination unit 622, the above difference is not within ± 1% of the R color gradation value UR of the background (in other words, the R color gradation value SR of the extracted pixel is outside the range of the range RG1). In this case, it is determined that the R color gradation value SR of the extracted pixel is not in the vicinity of the R color gradation value UR of the background.

FIG. 11 is a histogram showing the relationship between the R color gradation value of the pixel of the trace portion where the characters drawn with the heat erasable ink (non-fluorescent color) are erased and the R color gradation value of the background of the document. Is.

With reference to FIGS. 8 and 11, the R color maximum value determination unit 623 extracts pixels in the document in the input image data one by one, and the R color gradation value SR of the extracted pixels is a gradation value. It is determined whether or not it is the maximum value of the detected value of. When the R color maximum value determination unit 623 determines that the R color gradation value SR of the extracted pixel is the maximum value, it outputs "1" to the selection unit 627. When the R color maximum value determination unit 623 determines that the R color gradation value SR of the extracted pixel is not the maximum value, it outputs "0" to the selection unit 627.

When the pixel of the trace part where the characters drawn with the heat-erasable ink (non-fluorescent color) is erased is extracted, the R color gradation value of the pixel becomes the maximum value LRMax, and the R color gradation of the background of the original. Greater than the value UR.

With reference to FIG. 8, the saturation detection unit 624 sequentially extracts the pixels in the document in the input image data one by one, and detects the saturation CF of the extracted pixels based on the RGB input image data. .. The largest value among the R color gradation value SR, G color gradation value SG, and B color gradation value SB of the extracted pixels is set as the maximum value Max (SR, SG, SB), and the gradation values SR, SG. , And when the smallest value among SBs is set to the minimum value Min (SR, SG, SB), the saturation CF of the extracted pixels is calculated using, for example, the following equation (2).

CF = Max (SR, SG, SB) -Min (SR, SG, LB) ... (2)

The hue discrimination unit 625 extracts pixels in the document in the input image data one by one in order, and determines whether or not the hue of the extracted pixels is R color based on the image data of each RGB color. In the hue discrimination unit 625, when the R color gradation value SR, the G color gradation value SG, and the B color gradation value SB of the extracted pixels satisfy the condition of the following formula (3), the hue of the extracted pixel is R. It is determined that it is a color, and "1" is output to the terminal IN2 of the AND type circuit 629. On the other hand, the hue discrimination unit 625 determines that the hue of the extracted pixel is not R color when the condition of the following equation (3) is not satisfied, and outputs "0" to the terminal IN2 of the AND type circuit 629.

｜ SR-SG ｜＞｜ SG-SB ｜ ・ ・ ・ (3)

The background saturation detection unit 626 detects the saturation CFA of the background of the document based on the gradation values UR, UG, and UB of each RGB color of the background of the document detected by the background gradation value detection unit 621. The largest value among the R color gradation value UR, G color gradation value UG, and B color gradation value UB of the background of the original is set to the maximum value Max (UR, UG, UB), and the gradation values UR, UG. When the smallest value among UB and UB is set to the minimum value Min (UR, UG, UB), the saturation CFA of the background of the document is calculated using, for example, the following formula (4).

CFA = Max (UR, UG, UB) -Min (UR, UG, UB) ... (4)

The selection unit 627 selects either one of the discrimination result by the R color neighborhood discrimination unit 622 and the discrimination result by the R color maximum value discrimination unit 623, and the selected discrimination result (input value from the selected member) is AND type. Output to terminal IN1 of circuit 629.

FIG. 12 is a diagram showing an example of a screen displayed on the operation display unit 33.

With reference to FIGS. 8 and 12, the operation display unit 33 may accept input for setting the type of ink contained in the document when receiving an image reading execution instruction from the user.

The screen displayed on the operation display unit is a screen that accepts input for setting the type of ink contained in the document, and includes keys KY1, KY2, and KY3. The key KY1 is a key that accepts the selection that the type of ink contained in the original is a heat-erasable ink that is not a fluorescent color. The key KY2 is a key that accepts the selection that the type of ink contained in the original is a fluorescent color heat-erasable ink. When one of the keys KY1 and KY2 is selected and the key KY3 for executing the job is accepted, the image forming apparatus 1 receives an instruction to execute image reading and the type of ink contained in the document. Accepts the setting that is the selected type.

When the input of the setting of the type of ink contained in the original is accepted, the selection unit 627 makes the above selection based on the accepted setting. That is, when the setting that the type of ink contained in the document is not the fluorescent color heat-erasable ink is accepted, the selection unit 627 selects the discrimination result by the R color neighborhood discrimination unit 622. When the setting that the type of ink contained in the document is fluorescent color heat-erasable ink is accepted, the selection unit 627 selects the discrimination result by the R color maximum value discrimination unit 623.

With reference to FIG. 8, the low saturation determination unit 628 receives the input of the saturation CF of the extracted pixel from the saturation detection unit 624, and the input of the saturation CFA of the background of the document is input from the background saturation detection unit 626. Accepts and accepts the input of the fixed value R color saturation CFB. The low saturation determination unit 628 extracts the pixels in the document in the input image data one by one in order, and the saturation CF of the extracted pixels is higher than that of the background saturation CFA as shown in the following formula (5). It is determined whether or not the saturation of the R color is within a range smaller than that of the CFB.

CFA <CF <CFB ... (5)

When the low saturation determination unit 628 determines that the saturation CF of the extracted pixel is within the above range, the low saturation determination unit 628 outputs "1" to the terminal IN3 of the AND type circuit 629. On the other hand, when the low saturation determination unit 628 determines that the saturation CF of the extracted pixel is out of the above range, the low saturation determination unit 628 outputs "0" to the terminal IN3 of the AND type circuit 629.

The AND type circuit 629 extracts pixels in the document one by one in the R color input image data in order, and the values to be input to each of the terminals IN1, IN2, and IN3 of the extracted pixels are "1". In the case of, the value C of "1" is output to the input terminal C of the selection unit 631. On the other hand, the AND type circuit 629 sets the value C of "0" to the input terminal of the selection unit 631 when the value to be input to at least one of the terminals IN1, IN2, and IN3 is "0". Output.

FIG. 13 is a diagram illustrating gamma correction for the gradation values SR, SG, and SB of each RGB color of the extracted pixels.

With reference to FIGS. 8 and 13, the gradation value replacement unit 630 sequentially extracts the pixels in the document in the input image data one by one, and the gradation values SR, SG, and the gradation values SR, SG, and the RGB colors of the extracted pixels are Each of the SBs is replaced with each of the gradation values UR, UG, and UB of each color of the base RGB, and the gradation value B after the replacement is output to the selection unit 631.

When the extracted pixels are the pixels of the erase marks of the heat-erasable ink, the G color gradation value and the B color gradation value of the extracted pixels tend to decrease. In the gradation value replacement unit 630, as shown by an arrow in FIG. 13, the gamma values of the gradation values SG and SB of each GB color of the extracted pixels are changed to the gamma values of the gradation values UG and UB of each of the underlying RGB colors. Correction may be made to match.

The gradation values SR, SG, and SB of each RGB color of the pixels extracted from the image reading unit 31 are input to the selection unit 631 as the gradation value A, and the gradation value B is input from the gradation value replacement unit 630. , The value C is input from the AND type circuit 629.

The selection unit 631 sequentially extracts the pixels in the document in the input image data one by one, and for the extracted pixels, whether the value C input from the AND type circuit 629 is "1" or "0". To determine. When the value C input from the AND type circuit 629 is "1", it is determined that the extracted pixel is a portion of the erase mark of the heat-erasable ink. In this case, the selection unit 631 determines the gradation value of the extracted pixel as the gradation value B, and outputs the gradation value of the determined pixel together with the information on the position of the extracted pixel. As a result, the gradation values of the RGB colors of the extracted pixels are corrected to the gradation values UR, UG, and UB of each of the underlying RGB colors.

On the other hand, when the value C input from the AND type circuit 629 is "0", it is determined that the extracted pixels are not the erase marks of the heat-erasable ink. In this case, the selection unit 631 determines the gradation value of the extracted pixel as the gradation value A, and outputs the gradation value A of the determined pixel together with the information on the position of the extracted pixel. As a result, the gradation values SR, SG, and SB of each RGB color of the extracted pixels are maintained without being corrected.

The function of the ink partial correction processing unit 62 may be realized not only by the above circuit configuration but also by the CPU 2 executing the control program stored in the ROM 3 as shown in FIGS. 14 and 15. ..

14 and 15 are flowcharts showing the processes executed by the ink partial correction processing unit 62 in one embodiment of the present invention.

With reference to FIG. 14, when the CPU 2 receives the input image data of each RGB color from the image reading unit 31, the CPU 2 calculates the brightness of the background of the original based on the input image data of each RGB color, and based on the calculated brightness. The gradation values UR, UG, and UB of each RGB color of the background of the original are calculated (detected) (S101). Next, the CPU 2 calculates (detects) the saturation CFA of the background of the document based on the gradation values UR, UG, and UB of each RGB color of the background of the document (S103), and sets the saturation CFB of the R color. (S105). Subsequently, the CPU 2 extracts one pixel in the document (S107), and calculates the saturation CF of the extracted pixel based on the gradation values SR, SG, and SB of each RGB color of the extracted pixel (S109). ). Subsequently, the CPU 2 determines whether or not the setting that the type of ink contained in the document is a heat-erasable ink that is not a fluorescent color is accepted (S111).

When it is determined in step S111 that the setting that the type of ink contained in the original is not a fluorescent color is not accepted (NO in S111), the CPU 2 determines that the type of ink contained in the original is fluorescent. It is determined that the setting that the color is heat-erasable ink is accepted, and the process proceeds to step S131 of FIG.

When it is determined in step S111 that the setting that the type of ink contained in the document is a heat-erasable ink that is not a fluorescent color is accepted (YES in S111), the CPU 2 determines that the saturation CFA, R of the background of the document It is determined whether or not the color saturation CFB and the saturation CF of the extracted pixels satisfy the relationship of the equation (5) (S113).

When it is determined in step S113 that the saturation CFA of the background of the document, the saturation CFB of the R color, and the saturation CF of the extracted pixels satisfy the relationship of the equation (5) (YES in S113), the CPU 2 extracts. It is determined whether or not the R color gradation value SR, the G color gradation value SG, and the B color gradation value SB of the pixels satisfy the condition of the equation (3) (S115).

When it is determined in step S115 that the R color gradation value SR, the G color gradation value SG, and the B color gradation value SB of the extracted pixels satisfy the condition of the equation (3) (YES in S115), the CPU 2 , It is determined whether or not the R color gradation value SR of the extracted pixel is in the vicinity of the R color gradation value UR of the base of the document (S117).

In step S117, when it is determined that the R color gradation value SR of the extracted pixel is in the vicinity of the R color gradation value UR of the background of the document (YES in S117), the CPU 2 determines that the RGB color scale of the extracted pixel is Each of the metering SR, SG, and SB is replaced with each of the gradation values UR, UG, and UB of each RGB color of the base of the document (S119), and the process proceeds to step S151.

In step S113, when it is determined that the saturation CFA of the background of the document, the saturation CFB of the R color, and the saturation CF of the extracted pixel do not satisfy the relationship of the equation (5) (NO in S113), in step S115. , When it is determined that the R color gradation value SR, the G color gradation value SG, and the B color gradation value SB of the extracted pixels do not satisfy the condition of the equation (3) (NO in S115), or in step S117. When it is determined that the R color gradation value SR of the extracted pixel is not in the vicinity of the R color gradation value UR of the base of the document (NO in S117), the CPU 2 proceeds to the process of step S151 without performing replacement.

In step S151, the CPU 2 determines whether or not all the pixels in the document have been extracted (S151).

If it is determined in step S151 that all the pixels in the document are not extracted (NO in S151), the CPU 2 proceeds to the process of step S107.

If it is determined in step S151 that all the pixels in the document have been extracted (YES in S151), the CPU 2 ends the process.

With reference to FIG. 15, in step S131, the CPU 2 determines whether or not the saturation CFA of the background of the document, the saturation CFB of the R color, and the saturation CF of the extracted pixels satisfy the relationship of the equation (5). Determine (S131).

In step S131, when it is determined that the saturation CFA of the background of the document, the saturation CFB of the R color, and the saturation CF of the extracted pixels satisfy the relationship of the equation (5) (YES in S131), the CPU 2 extracts. It is determined whether or not the R color gradation value SR, the G color gradation value SG, and the B color gradation value SB of the pixels satisfy the condition of the equation (3) (S133).

When it is determined in step S133 that the R color gradation value SR, the G color gradation value SG, and the B color gradation value SB of the extracted pixels satisfy the condition of the equation (3) (YES in S133), the CPU 2 , It is determined whether or not the R color gradation value SR of the extracted pixel is the maximum value of the detected value (S135).

When it is determined in step S135 that the R color gradation value SR of the extracted pixel is the maximum value of the detected value (YES in S135), the CPU 2 determines that the RGB color gradation values SR, SG, and the extracted pixel of each RGB color. Each of the SBs is replaced with each of the gradation values UR, UG, and UB of each of the RGB colors of the base of the document (S137), and the process proceeds to step S151 of FIG.

In step S131, when it is determined that the saturation CFA of the background of the document, the saturation CFB of the R color, and the saturation CF of the extracted pixels do not satisfy the relationship of the equation (5) (NO in S131), in step S133. , When it is determined that the R color gradation value SR, the G color gradation value SG, and the B color gradation value SB of the extracted pixels do not satisfy the condition of the equation (3) (NO in S133), or in step S135. When it is determined that the R color gradation value SR of the extracted pixel is not the maximum value of the detected value (NO in S135), the CPU 2 proceeds to the process of step S151 in FIG. 14 without performing replacement.

[Effect of Embodiment]

According to the present embodiment, pixels in the erased marks of the heat-erasable ink are detected based on the characteristics peculiar to the image of the erased marks of the heat-erasable ink, and the gradation value of the extracted pixels is used as the base. Is replaced with the gradation value of. As a result, even if an infrared cut filter or a three-color LED is not used, it is possible to avoid a situation in which the R color is thinly reproduced in the erase mark portion of the heat-erasable ink, and an increase in manufacturing cost is suppressed. can do.

[Other]

The determination as to whether or not the portion is the erase mark portion of the heat-erasable ink may be performed in units of one pixel as described above, or may be performed in units of a plurality of pixels.

The processing in the above-described embodiment may be performed by software or by using a hardware circuit. It is also possible to provide a program that executes the processing according to the above-described embodiment, and record the program on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, or a memory card and provide the program to the user. You may decide to do it. The program is executed by a computer such as a CPU. Further, the program may be downloaded to the device via a communication line such as the Internet.

It should be considered that the above embodiments are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Image forming device 2 CPU (Central Processing Unit)
3 ROM (Read Only Memory)
4 Memory 5 HDD (Hard Disk Drive)
6 Image processing unit 10 Main controller 31 Image reading unit (an example of image acquisition means)
31a Image reading unit housing 32 Printer engine unit 33 Operation display unit (example of reception means)
34 Communication unit 35 Audio processing unit 36 Audio input unit 37 Audio output unit 38 Paper output tray 41 Drive unit 42 Light emitting unit 43 AD conversion unit (example of image generation means)
61, 63, 64, 65 ASIC (Application Specific Integrated Circuit)
62 Ink partial correction processing unit 100 Main controller 310 ADF (Auto Document Feeder)
311 Document tray 312 Paper output tray 321 Contact glass 321a, 322a Slit 322 Platen glass 323 Wire 324 Slider 325 Light source (example of irradiation means)
326,327 Mirror 328 Motor 329,330 Lens 331, 331B, 331G, 331R Line sensor (example of light receiving means)
621 Base gradation value detection unit (example of base level detection means)
622 R (red) color neighborhood discrimination unit (example of level discrimination means)
623 R color maximum value discriminating unit (an example of level discriminating means)
624 Saturation detection unit (an example of saturation determination means)
625 Hue Discrimination Unit (Example of Hue Discrimination Means)
626 Base saturation detection unit 627,631 Selection unit (example of replacement means)
628 Low-saturation discrimination unit 629 AND type circuit 630 Gradation value replacement unit FT Infrared cut filter IK Thermal erasable ink IN1, IN2, IN3 terminal KY1, KY2, KY3 key P1 Document reading position SN attribute signal

Claims (13)

Image acquisition means for acquiring image data of each color of red, green, and blue of the manuscript,
A background level detecting means for detecting the level of each color of red, green, and blue of the background of the document based on the image data of each color of red, green, and blue.
A level determination means for determining whether or not the red level at a specific position in the document is a predetermined value based on the red image data, and
A hue determining means for determining whether or not the hue at the specific position is red based on the image data of each of the red, green, and blue colors, and
A saturation determination means for determining whether or not the saturation at the specific position is within a predetermined range based on the image data of each of the red, green, and blue colors.
The level determination means determines that the red level at the specific position is the predetermined value, and the hue determination means determines that the hue at the specific position is red, and the specific When the saturation determination means determines that the saturation of the position is within the predetermined range, the replacement means replaces the level of each color of red, green, and blue at the specific position with the level of each color of red, green, and blue of the base. An image processing device equipped with. The image acquisition means
Irradiation means for irradiating the document with light,
A light receiving means that receives reflected light from the document and
An image generation means for generating image data of each color of red, green, and blue based on the reflected light, and the red image data based on light in a red wavelength region and an infrared wavelength region included in the reflected light. The image processing apparatus according to claim 1, further comprising an image generating means for generating the image. The level determining means determines whether or not the red level at the specific position is in the vicinity of the red level of the base.
The replacement means determines by the level determining means that the red level at the specific position is close to the red level of the base, and the red level at the specific position is the red level of the base. Image data of each color of red, green, and blue when the hue discriminating means determines that the area is in the vicinity of, and the saturation discriminating means determines that the saturation of the specific position is within the predetermined range. The image processing apparatus according to claim 1 or 2, wherein the level of each color of red, green, and blue at the specific position in the above is replaced with the level of each color of red, green, and blue at the position of the base. When the difference between the red level at the specific position and the red level of the base is within ± 1% of the red level of the base, the level determining means determines the red level at the specific position. The image processing apparatus according to claim 3, wherein is determined to be in the vicinity of the red level of the background. The level determining means determines whether or not the red level at the specific position is the maximum level of the detected value.
The replacement means determines by the level determining means that the red level at the specific position is the maximum level of the detected value, and the red level at the specific position is in the vicinity of the red level of the base. When the hue determination means determines that there is, and the saturation determination means determines that the saturation at the specific position is within the predetermined range, the identification in the image data of each color of red, green, and blue. The image processing apparatus according to claim 1 or 2, wherein the level of each color of red, green, and blue at the position of is replaced with the level of each color of red, green, and blue at the position of the base. The level determination means
A first determining means for determining whether or not the red level at the specific position is in the vicinity of the red level of the base.
A second determination means for determining whether or not the red level at the specific position is the maximum level of the detected value, and
Including a selection means for selecting one of the first and second determination means,
When the first level discriminating means is selected by the selecting means, the replacement means tells the first level discriminating means that the red level at the specific position is close to the red level of the base. The hue determination means determines that the hue at the specific position is red, and the saturation determination means determines that the saturation at the specific position is within the predetermined range. When this is done, the level of each red, green, and blue color at the specific position is replaced with the level of each color of red, green, and blue at the base position.
When the second level determination means is selected by the selection means, the replacement means determines that the red level at the specific position is the maximum level of the detected value by the second level determination means. When the hue determination means determines that the hue at the specific position is red and the saturation determination means determines that the saturation at the specific position is within the predetermined range. The image processing apparatus according to claim 1 or 2, wherein the level of each color of red, green, and blue at the specific position in the image data of each color of red, green, and blue is replaced with the level of each color of red, green, and blue at the base position. Further provided with a reception means for accepting input for setting the type of ink contained in the manuscript,
The image processing apparatus according to claim 6, wherein the selection means makes a selection based on the settings received by the reception means. The ground level detecting means is
A histogram creating means for creating a histogram showing the distribution of brightness in the image of the manuscript based on the image data of each color of red, green, and blue.
The level of each red, green, and blue color at the position in the document having the peak brightness in the histogram is extracted from the image data of each of the red, green, and blue colors, and the level of each extracted red, green, and blue color is detected as the level of each red, green, and blue color of the background. The image processing apparatus according to any one of claims 1 to 7, further comprising a level extraction means for The red level at the specific position in the red image data is defined as level SR, the green level at the specific position in the green image data is defined as level SG, and the blue color at the specific position in the blue image data. When the level SR, the level SG, and the level SB satisfy the condition of | SR-SG |> | SG-SB |, the hue discriminating means is at the specific position. The image processing apparatus according to any one of claims 1 to 8, wherein the hue of the image processing apparatus is determined to be red. The saturation determination means according to any one of claims 1 to 9, wherein the saturation determination means determines whether or not the saturation at the specific position is within a range larger than the saturation of the base and smaller than the saturation of red. The image processing apparatus described. The red level at the specific position in the red image data is defined as level SR, the green level at the specific position in the green image data is defined as level SG, and the blue color at the specific position in the blue image data. Level SB, and the maximum level among the level SR, the level SG, and the level SB is the maximum level Max (SR, SG, SB), and the level SR, the level SG, and the level SB. When the minimum level is the minimum level Mix (SR, SG, SB), the saturation determination means sets the saturation CF at the specific position to CF = Max (SR, SG, SB) -Mix (SR). , SG, SB). The image processing apparatus according to any one of claims 1 to 10. The replacement means corrects the gamma value of the level of each blue-green color at the specific position in the image data of each blue-green color so as to match the gamma value of the level of each blue-green color of the base. 11. The image processing apparatus according to any one of 11. The image acquisition step to acquire the image data of each color of red, green, and blue of the manuscript,
A background level detection step for detecting the level of each color of red, green, and blue of the background of the document based on the image data of each color of red, green, and blue.
A level determination step for determining whether or not the red level at a specific position in the document is a predetermined value based on the red image data, and
A hue determination step for determining whether or not the hue at the specific position is red based on the image data of each of the red, green, and blue colors, and
A saturation determination step for determining whether or not the saturation at the specific position is within a predetermined range based on the image data of each color of red, green, and blue.
The level determination step determines that the red level at the specific position is the predetermined value, and the hue determination step determines that the hue at the specific position is red, and the specific When the saturation determination step determines that the saturation of the position is within the predetermined range, the replacement step of replacing the level of each red, green, and blue color at the specific position with the level of each red, green, and blue color of the base. A control program for an image processing device that causes a computer to execute.

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