JP2011254473A - Image processing system, method for the same, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing system, a method for the same, and an image forming device capable of setting up a density after monochrome conversion for every hue in the case where a color image is output as a monochrome image.SOLUTION: In an embodiment, the image processing system is provided with input means by which a density value is input with respect to a hue associated with a color of an input image of which density adjustment is to be carried out, and monochrome brightness adjustment means that, in each of a case where a Lab value of the color of the input image is located on color gamut outline curve data and of a case where the Lab value is located in a different region from on the color gamut outline curve, using the density value input from the input means, suppresses the maximum of an output gradation value in the case where the color of the input image is a color having high brightness, and enhances the maximum of the output gradation value in the case where the color of the input image is a color having high chroma saturation and low brightness.

Description

  Embodiments described herein relate generally to an image processing apparatus and method, and an image forming apparatus.

  The image forming apparatus uses a color material of C (cyan), M (magenta), and Y (yellow (yellow)) for reproducing color (chromatic color) and a color of Bk (black) for reproducing black (achromatic color). Using the material, a visible image corresponding to the image data is formed and output to a sheet medium.

JP 2006-262471 A

  Depending on the color gamut of the image data (input image) (for example, sRGB (standard RGB) or L * a * b * (CIE (Commission Internationale de L'eclairage <France> International Lighting Commission))) Yellow (yellow, Y) may have high brightness, and blue (blue, B) may have low brightness. When such image data is output as a monochrome image, yellow (Y) is printed light and blue (B) is printed dark.

  For this reason, when an image with high brightness such as yellow (Y) is converted to a monochrome (black single color, Bk) image and output, the brightness difference between yellow (Y) and the color of the paper base (sheet medium) becomes small. This makes it difficult to distinguish between the image and the background. Also, when a document in which black (Bk) characters and blue (B) characters are mixed is converted to monochrome (monochrome black), the blue (B) character and black ( Bk) The brightness difference from the character becomes small, and the identification becomes difficult.

  From such a background, when outputting a chromatic image as a monochrome (black single color) image, for example, for a color with high brightness, the maximum value is suppressed, and for a color with high saturation and low brightness. It is preferable that the density after monochrome conversion can be set for each hue, such as increasing the brightness.

  An object of the present invention is to provide an image processing apparatus and method, and an image forming apparatus capable of setting the density after monochrome conversion for each hue when a chromatic image is output as a monochrome (black single color) image. It is.

  In the embodiment, the image processing apparatus includes an input unit that inputs a density value for a hue related to the color of the input image to be density-adjusted, and a Lab value of the color of the input image located on the color gamut contour curve data. And the Lab value is located in a region different from the color gamut contour curve, the density value input from the input means is used, and when the color of the input image is a high brightness color, the output gradation value And a monochrome lightness adjustment unit that suppresses the maximum value and increases the maximum output gradation value when the color of the input image is a color with high saturation and low lightness.

Schematic which shows an example of embodiment. Schematic which shows an example of embodiment. Schematic which shows an example of embodiment. Schematic which shows an example of embodiment. Schematic which shows an example of embodiment. Schematic which shows an example of embodiment. Schematic which shows an example of embodiment. Schematic which shows an example of embodiment. Schematic which shows an example of embodiment.

  Hereinafter, embodiments will be described with reference to the drawings.

  1 includes at least an image forming unit 3, a data management unit 5, a communication control unit 7, and a system control unit 9. The MFP 1 is connected to an arbitrary number of clients (users) such as personal computers (PCs) 101,..., N through a communication control unit described later.

  The image forming unit 3 visualizes images and characters based on arbitrary format data and outputs them on a sheet medium. The data management unit 5 receives data and manages the data for execution of jobs such as print output and storage. The communication control unit 7 manages data transmission / reception with a communication line (network network). The system control unit 9 controls the operation of the image forming unit 3, the data management unit 5, the communication control unit 7, that is, the MFP 1.

  The image forming unit 3 includes at least a power supply unit 31, a scanner unit 32, a memory unit 33, an image forming unit 34, a monochrome brightness adjustment unit 35, a color conversion unit 36, and a process control unit (process controller) 37. The image forming unit 3 also includes a sheet medium supply mechanism that holds an image output from the image forming unit 34 and supplies the image to the image forming unit 34.

  The power supply unit 31 is connected to a commercial power supply and generates a secondary side voltage used for the operation of the MFP 1 from the primary side (input) voltage. Of course, the input allowable current value (upper limit) is managed for the primary side voltage.

  When the image forming unit 34 visualizes and outputs information on the sheet medium, such as images, characters, shapes, colors, and the like are in a non-data format, the scanner unit 32 outputs the information as image data. The scanner unit 32 shines light on a sheet-like document or three-dimensional object including information, acquires an electrical signal corresponding to the intensity of the light (image light) reflected by the information (image light), and converts it into image data. .

  The memory unit 33 holds original image data obtained by the scanner unit 32, output data from a personal computer (PC), or image data input from the outside such as facsimile reception data. The memory unit 33 also stores programs, applications (software), and the like.

  The image forming unit 34 visualizes the image data and outputs it on a sheet medium. As a visualization method, there are many electrostatic transfer methods using toner and direct recording methods (inkjet) using ink. A hot stamp or the like for outputting a special color (gold / silver) may be used in combination.

  The monochrome brightness adjustment unit 35 converts the color image data into monochrome image data in response to a request to output the color image data as a monochrome (black single color) image in a color conversion table referred to when the color conversion unit 36 outputs the output image data. In the case where the image data including the difference between the image with high brightness and the background color of the sheet medium or the image information of two or more colors with small brightness differences is output as a monochrome image (easiness of identification) In order to improve the image quality, etc., the gradation value (density data) of the monochrome image used when outputting the monochrome image is set for each pixel of the image data with a small brightness difference according to the brightness and the saturation (monochrome brightness adjustment). As an example of setting, when a color image is output as a monochrome image, for example, the maximum value is suppressed for a color with high brightness, and the brightness is increased for a color with high saturation and low brightness, etc. There is.

  The color conversion unit 36 includes at least a color conversion table that is referred to when the image forming unit 34 visualizes the image data and outputs the image data as an output image, and reflects the result of density adjustment by the monochrome brightness adjustment unit 35 while forming an image. The color (color material and its amount) used when the unit 34 outputs an output image is set.

  The process control unit 37 includes a CPU (microprocessor) and controls each unit of the image forming unit 3.

  The data management unit 5 includes a data input unit 51 that receives data, a data processing unit 52 that processes the data received by the data input unit 51 for execution of jobs such as print output and storage, and data processed by the data processing unit 52 A data output unit 53 that outputs the data in a format specified by the job, and a data control unit (data controller) 54 that controls data exchange between the data input unit 51, the data processing unit 52, and the data output unit 53. Including at least.

  The communication control unit 7 is connected to a public communication line and receives or transmits facsimile (FAX) data. The communication control unit 7 is connected to an external network such as a LAN (local area network) and receives data from the network. A LAN control unit 72 for transmission, for example, an extended interface unit 73 corresponding to a USB (Universal Serial Bus) standard and receiving or transmitting data from a connected party, a facsimile unit 71, a LAN control unit 72, and an extended interface unit 73 At least a communication control unit (communication controller) 74 for controlling communication with the other party, data input and output, parallel processing, and the like. As described above, the MFP 1 is connected to an arbitrary client (user), for example, a personal computer (PC) 101,..., N via the LAN control unit 72, and also functions as a network printer.

  The system control unit 9 includes at least a main control block (MPU) 91, an input unit (switch or button group) or a user interface unit (operation unit) 93 in which an input panel (touch panel) and a display unit 92 are integrated. . The MPU 91 is mutually connected to the process controller (CPU) 37, the data controller 54, and the communication controller 74 of each unit described above, and controls each unit.

  The MPU 91 is connected to the operation unit (user interface unit) 93, and starts and stops operation of each unit, condition setting, and an output image output from the image forming unit 34 of the image forming unit 3 from the touch panel of the display unit 92. For example, it accepts a setting of an achromatic color adjustment amount for improving the reproducibility of a black image, and outputs a control signal for controlling the operation of each unit in response to an instruction input.

  The touch panel (display unit) 92 detects an instruction (control) input by a user's finger, and inputs (instructs) the MPU 91 to start up copying, scanning start, display of scanned data or incoming facsimile data, and the like.

  It is connected to the MPU 91 or the timer unit 94. The timer unit 94 sets the year (yyyy), month (mm), day (DD), hour (HH), and minute (MM) based on the clock generated by the built-in clock generation unit (CLK), for example, a facsimile document. The received date / time, the transmitted date / time, the scan date / time displayed by the scanner, and the file can be saved (attached to the file name). The clock generation unit (CLK) may be provided in the system control unit 9 for the operation of the MPU 91. The timer unit 94 may count the time or hold the time data, for example, using the frequency of the commercial power input to the power supply unit 31 of the image forming unit 3 / time data (time signal) included in the (spatial wave) broadcast signal. Service signal) may be received directly.

  FIG. 2 shows an outline of monochrome brightness adjustment processing on the printer driver screen on the PC (client) side for the image output by the client (PC) 101,...

  As described above, the monochrome brightness adjustment process is performed when, for example, image data including image information of two or more colors having a small difference in brightness or a difference between an image having a high brightness and a background color of the sheet medium is output as a monochrome image. In order to improve the visibility (easiness of identification) of the mutual colors, the gradation value of the monochrome image used when outputting the monochrome image is set.

  That is, on the printer driver screen on the client (PC) 101 side, a GUI (Graphical User Interface) for receiving monochrome density input settings for each hue is displayed (1), and an input for monochrome density settings for each hue is received (2). ), Monochrome color conversion is performed on the MFP 1 side (3). In the monochrome color conversion, specifically, the gradation of a monochrome image is set by changing the brightness and saturation for each pixel. The monochrome density here indicates an image gradation value after monochrome conversion. In this case, the image gradation value after monochrome conversion is, for example, 256 levels in 8-bit display, and is in the range of 0 to 255.

  More specifically, the monochrome brightness adjustment processing is shown in FIG. 3 as an example, but a hexagon 101-111 capable of displaying six hues of RGB (three primary colors used for additive color mixture) and CMY (three elements used for subtractive color mixture), And input areas (text boxes) 111-1, 111-2,..., 111-n-1, 111-n where n can be set for each hue indicated by the top of the hexagon (n is a positive integer) ) Including GUI (Graphical User Interface) 101-11 is displayed on the printer driver screen 101-1, and the gradation value of the monochrome image after the monochrome conversion of the color original, that is, the input image, is displayed in each text box. By inputting (user instruction value), the monochrome brightness adjustment unit 35 on the MFP 1 side changes the gradation value of the monochrome image. Is shall. The six hues are divided into R (Red, Red), G (Green, Green), and B (Blue, Blue) at intervals of 120 °, and C (Cyan) which is a complementary color of each of the six hues. , M (Magenta) and Y (Yellow) are applied to the same circle, so that every 60 °, the position of 180 ° is 120 ° from C and R, with R as the reference 0 ° (angle from R) A position where G is a position apart from G (an angle from R) is 300 ° and a position which is 120 ° away from G and R is a position B (an angle from R) is Y. It is a color scheme.

  In FIG. 3, each text box can directly accept the gradation value of the monochrome image desired by the user by inputting a numerical value of 0 to 100 (%). The tone value can be set in the monochrome brightness adjustment unit 35 on the MFP 1 side.

  The monochrome density of each hue corresponds to a specific gradation value of the input color image. The specific gradation values are RGB (255, 0, 0) for hue R, RGB (255, 255, 0) for hue Y, RGB (0, 255, 0) for hue G, and hue C. Are RGB (0, 255, 255), the hue B is RGB (0, 0, 255), and the hue M is RGB (255, 0, 255).

  The GUI 101-11 on the printer driver screen 101-1 displays an “OK” button for outputting a control command for validating the monochrome density input in the text box (execution of processing by the image forming unit 3). 101-12 and a “cancel” display 101-13 for outputting a control command for canceling the input to the text box (does not execute the processing by the image forming unit 3).

  Hereinafter, the monochrome lightness adjustment, which has been outlined with reference to FIGS. 2 and 3, will be described in detail with reference to FIGS. 4 to 9 can be realized by the monochrome brightness adjustment unit of the image forming unit shown in FIG. Further, each of the six hues will be described by using an arbitrary one hue, for example, Y (yellow).

  FIG. 4 shows an example of color conversion of an input color image to a monochrome image. Input is performed so that the Y point (one point in each of the six hues) designated on the printer driver screen described in FIG. An example of converting a color image and outputting a monochrome image is shown.

  First, an L * a * b * (CIE) value corresponding to the RGB value of the input color image is obtained. Hereinafter, in the present embodiment, since it is clear that it is CIELab, it is simply indicated as “Lab (value)”.

  That is, color conversion is performed using the RGB-Lab conversion table, and a Lab value (output Lab value) corresponding to the RGB value of the input image signal is obtained.

  Next, in the color gamut of the input color image, a monochrome gradation value (0 to 255) is obtained using the (obtained) output Lab value. It is assumed that the white point of the color gamut of the input color image is the monochrome gradation value 0, and the black point is the monochrome gradation value 255.

  Hereinafter, the monochrome density (%) set on the printer driver screen is multiplied by the maximum gradation value 255 (16 × 16 = 256, but including “0”) to obtain an arbitrary point in the hue. Monochrome gradation value at is obtained.

  For example, the monochrome gradation value is 154 (255 × 0.6) if the monochrome density specified on the printer driver screen is 60%. If the monochrome density is 50%, it is 128 (255 × 0.5), and if it is 40%, it is 102 (255 × 0.4).

  It should be noted that any one point of each of the six hues and other than the eight points that are the white point (gradation value 0, generally L * = 100) and the black point (gradation value 255, generally L * = 0). Based on the Lab value, monochrome gradation values after monochrome conversion are obtained for each of the color gamut outline (indicated by the bold line (outline) in FIG. 4) and inside (inside the outline in FIG. 4).

  First, it is determined whether or not the color to be color-converted, that is, the Lab value of the input color image is on the color gamut outline.

[1] Color gamut outline determination (see FIG. 5)
a) Based on the RGB-Lab conversion table, outline curve data indicating the gamut outline of the input color image as C * and L * is obtained.

    b) Next, the first Lab value of the input image data is obtained based on the RGB value of the input color image and the RGB-Lab conversion table.

    c) Next, it is determined whether or not the (obtained) first Lab value exists in the color gamut outline represented by the outline curve data.

  If the Lab value is present on the color gamut outline as a result of the determination, the following processing <[2] · [3]> is executed. As a result of the determination, if the Lab value does not exist on the color gamut outline, the monochrome method described in << [4] · [5] >> is executed.

[2] Obtain monochrome gradation value of maximum saturation (see FIGS. 6 and 7)
The hue is specified for each pixel of the input color image, the maximum saturation point in the color gamut where the saturation is maximum in the <specified> hue is determined, and the monochrome gradation at the <determined> maximum saturation point is determined. Find the value (perform processing).

    1) The Lab value of the input color image converted using the RGB-Lab conversion table is calculated, and the hue angle for each pixel of the input color image is obtained (FIG. 6).

    2) Two hues among the six hues sandwiching the obtained hue angle are discriminated (FIG. 6). In the example of FIG. 6, the two hues are “Y” and “R” based on the rule between 6 hues and Lab values a * and b * (association when establishing Lab (CIE)). I understand that.

3) Therefore, the formula <A> shown below

To "the angle (b) between the R point and the maximum saturation point (the point between the R point and the maximum saturation point)" is changed from the "Y point to the maximum saturation point (the Y point and the maximum saturation point). The product of the value (quotient) divided by “angle (a)” and “difference in monochrome density (%) between Y point and R point” is obtained, and monochrome at the maximum saturation point (between << Y-R >>) The concentration (%) is obtained (FIG. 7). Note that the monochrome density (%) of the Y point and the R point is a value set in each text box of the GUI 101-11 shown in FIG. Further, the above-mentioned division of “angle (b) / angle (a)” substantially divides the distance between the R point and the maximum saturation point by the distance between the R point and the Y point (proportional). It is similar to distributing.

    4) Next, the monochrome gradation value (%) is multiplied by the maximum gradation value 255 (actually 256) to obtain a monochrome gradation value (point X).

[3] Calculate monochrome gradation values on the color gamut outline (see FIG. 8)
A) RGB (255, 255, 255) converted to Lab values using the RGB-Lab conversion table, white point (monochrome gradation value is “0”), RGB (0, 0, 0) is converted to RGB-Lab Using the black point (monochrome gradation value “255”) and the maximum saturation (Y point in FIG. 8) converted into the Lab value by the table, the following formula <B>

In any case, the monochrome gradation value of the color gamut outline portion is obtained. When the L value of the point (X) on the outline is larger than the L value of the maximum saturation (Y point), the L value of the point (X) on the outline is also the maximum saturation ( If the value is smaller than the L value at point Y), the formula <C> is used.

On the other hand, when the calculated Lab value is located inside the color gamut, as in the case where the Lab value exists on the color gamut outline,
[4] Monochrome gradation value of maximum saturation is obtained (see FIGS. 6 and 7).
Even when the Lab value of the input color image exists within the color gamut, the maximum saturation is obtained by the same method as in [2].
[5] Obtain the monochrome gradation value in the color gamut (see FIG. 9)
B) RGB (255, 255, 255) converted into Lab values using the RGB-Lab conversion table, white points (monochrome gradation value is “0”), and RGB (0, 0, 0) are RGB-Lab A black point (monochrome gradation value “255”) converted to a Lab value by a conversion table is obtained,
C) A straight line (on L *) connecting the white point and the black point where the monochrome gradation value changes from 0 to 255 is obtained.

    D) Next, the “first point” having the same value as the monochrome gradation value of the maximum saturation obtained in [4] is defined on the obtained straight line.

    E) Next, the obtained “first point” and the maximum saturation (point) are connected to form a “specified density line”.

F) Next, the “monochrome gradation value” is expressed by the following formula <D>

Apply and seek. In Formula <D>, when the Lab value of the input color image is located above the “specified density line” (white point side), and when the Lab value of the input color image is below the “specified density line” ( In the case of being located on the black spot side), the “first distance” and the “second distance” are set as follows according to either [G)] or [H)].

    G) When the Lab value of the input color image is located above the “specified density line” (white point side), pass the “first distance” from the white point through the Lab value of the input color image, The distance from the position intersecting with the “straight line” (referred to as “second point”) is defined as the distance from the white point to the Lab value of the input color image as “second distance”.

    H) When the Lab value of the input color image is located below the “specified density line” (black dot side), the “first distance” is passed from the black point through the Lab value of the input color image and the specified density line ” The distance from the black point to the Lab value of the input color image is defined as the “second distance”.

By applying the above-described embodiment, a color original (image data) in which a difference between an image having a high brightness and a background color of a sheet medium or an object having a small brightness difference is mixed is converted into a monochrome image, and an output image is converted. In the formation, the brightness difference between the objects can be sufficiently increased, and the visibility of the printed image (printout) can be improved.

  3 has been described as a display example of the printer driver screen (client side), it may be displayed on the display unit (touch panel) 92 of the MFP 1. That is, when a user (client) who has instructed printing (output image output) goes to the MFP 1 to obtain an output image (printout), the output image is confirmed and the brightness difference between objects is further adjusted. It is possible. In this case, a GUI 101-11 including a printer driver screen (polygon display 101-111 and text boxes 111-1, 111-2, ..., 111-n-1, 111-n (n is a positive integer)). In the numerical value setting (numerical value) in the text box, a numerical key group capable of inputting numbers “0” to “9” held by the display unit 92 is used.

  The change information input to the monochrome brightness adjustment unit 35 is temporarily held by the monochrome brightness adjustment information temporary holding unit 11. The monochrome brightness adjustment information temporary holding unit 11 may be provided on any of the PC (client) 101,..., N side / MFP1 side (FIG. 1 shows an example held on the MFP1 side for convenience).

  “Input” / “setting change” or the like temporarily held by the monochrome brightness adjustment information temporary holding unit 11 is stored, for example, in the memory unit 33 (of the MFP 1) when the setting change / input is confirmed. Note that the monochrome brightness adjustment information temporary holding unit 11 can also be used as the memory unit 33 when it is not affected by the writing / reading speed of the memory unit 33 or the like. Of course, “input” / “setting change” or the like may be temporarily stored in the memory on the PC side and supplied to the MFP 1 side when it is confirmed.

  As described above, by applying the present embodiment, the image data including the difference between the image with high lightness and the background color of the sheet medium or the image information of two or more colors with small lightness difference is converted into a monochrome image. As a result, it is possible to improve the visibility (easiness of identification) of the mutual colors and the like.

  That is, the brightness difference between objects when a color original containing a mixture of objects having a small brightness difference is converted into monochrome, and the visibility of a printed image (print output) is improved.

  In particular, for example, for a color with high brightness, the maximum value can be suppressed, and for a color with high saturation and low brightness, the brightness can be increased.

  The gradation value (density data) of the monochrome image used when outputting the monochrome image can be arbitrarily set by the user, and a density that can be easily identified can be set by confirming the output image (printout).

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... MFP (image forming apparatus), 3 ... Image forming part, 5 ... Data management part, 7 ... Communication control part, 9 ... System control part, 11 ... Monochrome brightness adjustment information holding unit, 32 ... Scanner unit, 33 ... Memory Unit 34... Image forming unit 35 35 monochrome brightness adjustment unit 36 color conversion unit 37 process control unit (process controller) 51 data input unit 52 data processing unit 53 data output unit 72 ... LAN control unit, 73 ... expansion interface unit, 74 ... communication control unit (communication controller), 91 ... main control block (MPU), 92 ... display unit (touch panel), 93 ... user interface unit (operation unit), 101- 1 ... Printer driver screen, 101-11 GUI (graphical user interface).

Claims (7)

Input means for inputting a density value for a hue related to the color of the input image to be density-adjusted;
In accordance with the density value input from the input means, monochrome brightness adjustment means for obtaining a gradation value as a monochrome black image of the color of the input image whose density is to be adjusted;
Comprising
The monochrome brightness adjustment means includes:
Obtain the gamut contour curve data of the color of the input image,
Find the first Lab value (CIE) of the color of the input image,
When the obtained first Lab value is located on the color gamut contour curve,
Identify the hue of each pixel of the input image color,
Find the maximum saturation point in the color gamut that maximizes saturation in the specified hue,
Calculate the Lab value of the color of the input image using the maximum saturation point, find the hue angle for each pixel,
Determine the two hues that sandwich the calculated hue angle,
Using the difference between the two hues determined and the angle between one of the hues of the maximum saturation point and the two hues determined, the difference between the density values input by the input means is used to obtain a monochrome black Output tone value as
An image for obtaining a monochrome gradation value using a white point converted to a Lab value (monochrome gradation value is “0”), a black point converted to a Lab value (monochrome gradation value is “maximum value”), and maximum saturation. Processing equipment. Input means for inputting a density value for a hue related to the color of the input image to be density-adjusted;
In accordance with the density value input from the input means, monochrome brightness adjustment means for obtaining a gradation value as a monochrome black image of the color of the input image whose density is to be adjusted;
Comprising
The monochrome brightness adjustment means includes:
Obtain the gamut contour curve data of the color of the input image,
Find the first Lab value (CIE) of the color of the input image,
When the calculated first Lab value is located in a different area from the color gamut contour curve,
Identify the hue of each pixel of the input image color,
Find the maximum saturation point in the color gamut that maximizes saturation in the specified hue,
Calculate the Lab value of the color of the input image using the maximum saturation point, find the hue angle for each pixel,
Determine the two hues that sandwich the calculated hue angle,
Using the difference between the two hues determined and the angle between one of the hues of the maximum saturation point and the two hues determined, the difference between the density values input by the input means is used to obtain a monochrome black Output tone value as
Defining a first straight line connecting the white point converted to the Lab value (monochrome gradation value is “0”) and the black point converted to the Lab value (monochrome gradation value is “maximum value”);
A first point having the same value as the gradation value defined by the maximum saturation point is defined on the first straight line.
Define a second straight line connecting the first point and the maximum saturation point,
Define a third straight line connecting the white point and the color of the input image,
Defining a second point where the third straight line intersects the second straight line;
The ratio between the distance between the color of the input image on the third straight line and the white point, the ratio between the color of the input image on the third straight line and the second point, and the density value of the second point An image processing apparatus for obtaining a monochrome gradation value. The image processing apparatus according to claim 1, wherein the input unit includes a graphical user interface screen and can directly input density values of individual hues within a range of 0 to 100 (%). Obtain the gamut contour curve data of the color of the input image,
Find the first Lab value (CIE) of the color of the input image,
When the obtained first Lab value is located on the color gamut contour curve,
Identify the hue of each pixel of the input image color,
Find the maximum saturation point in the color gamut that maximizes saturation in the specified hue,
Calculate the Lab value of the color of the input image using the maximum saturation point, find the hue angle for each pixel,
Determine the two hues that sandwich the calculated hue angle,
Using the difference between the two hues determined and the angle between one of the hues of the maximum saturation point and the two hues determined, the difference between the density values input by the input means is used to obtain a monochrome black Output tone value as
An image for obtaining a monochrome gradation value using a white point converted to a Lab value (monochrome gradation value is “0”), a black point converted to a Lab value (monochrome gradation value is “maximum value”), and maximum saturation. Processing method. Obtain the gamut contour curve data of the color of the input image,
Find the first Lab value (CIE) of the color of the input image,
When the calculated first Lab value is located in a different area from the color gamut contour curve,
Identify the hue of each pixel of the input image color,
Find the maximum saturation point in the color gamut that maximizes saturation in the specified hue,
Calculate the Lab value of the color of the input image using the maximum saturation point, find the hue angle for each pixel,
Determine the two hues that sandwich the calculated hue angle,
Using the difference between the two hues determined and the angle between one of the hues of the maximum saturation point and the two hues determined, the difference between the density values input by the input means is used to obtain a monochrome black Output tone value as
Defining a first straight line connecting the white point converted to the Lab value (monochrome gradation value is “0”) and the black point converted to the Lab value (monochrome gradation value is “maximum value”);
A first point having the same value as the gradation value defined by the maximum saturation point is defined on the first straight line.
Define a second straight line connecting the first point and the maximum saturation point,
Define a third straight line connecting the white point and the color of the input image,
Defining a second point where the third straight line intersects the second straight line;
The ratio between the distance between the color of the input image on the third straight line and the white point, the ratio between the color of the input image on the third straight line and the second point, and the density value of the second point An image processing method for obtaining a monochrome gradation value. 6. The image according to claim 4, wherein the density value of each hue related to the color of the input image to be density-adjusted can be directly input within a range of 0 to 100 (%) using a graphical user interface screen. Processing method. Input means for inputting a density value for a hue related to the color of the input image to be density-adjusted;
Obtain the gamut contour curve data of the color of the input image,
Find the first Lab value (CIE) of the color of the input image,
When the obtained first Lab value is located on the color gamut contour curve,
Identify the hue of each pixel of the input image color,
Find the maximum saturation point in the color gamut that maximizes saturation in the specified hue,
Calculate the Lab value of the color of the input image using the maximum saturation point, find the hue angle for each pixel,
Determine the two hues that sandwich the calculated hue angle,
Using the difference between the two hues determined and the angle between one of the hues of the maximum saturation point and the two hues determined, the difference between the density values input by the input means is used to obtain a monochrome black Output tone value as
Using the white point converted to the Lab value (monochrome gradation value is “0”), the black point converted to the Lab value (monochrome gradation value is “maximum value”), and the maximum saturation, the monochrome gradation value is obtained.
When the calculated first Lab value is located in a different area from the color gamut contour curve,
Identify the hue of each pixel of the input image color,
Find the maximum saturation point in the color gamut that maximizes saturation in the specified hue,
Calculate the Lab value of the color of the input image using the maximum saturation point, find the hue angle for each pixel,
Determine the two hues that sandwich the calculated hue angle,
Using the difference between the two hues determined and the angle between one of the hues of the maximum saturation point and the two hues determined, the difference between the density values input by the input means is used to obtain a monochrome black Output tone value as
Defining a first straight line connecting the white point converted to the Lab value (monochrome gradation value is “0”) and the black point converted to the Lab value (monochrome gradation value is “maximum value”);
A first point having the same value as the gradation value defined by the maximum saturation point is defined on the first straight line.
Define a second straight line connecting the first point and the maximum saturation point,
Define a third straight line connecting the white point and the color of the input image,
Defining a second point where the third straight line intersects the second straight line;
The ratio between the distance between the color of the input image on the third straight line and the white point, the ratio between the color of the input image on the third straight line and the second point, and the density value of the second point A monochrome brightness adjustment means for obtaining a monochrome gradation value;
Using the gradation value obtained by the monochrome brightness adjustment means, the maximum value is suppressed for a color with high brightness, and an output that forms a monochrome output image with increased brightness for a color with high saturation and low brightness Image forming means;
An image forming apparatus comprising:

Images