JP3679253B2 - Color image output method, apparatus and recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color image output method and apparatus for generating and processing a gradation image, and a recording medium on which a color image output program is recorded, and is applied to a controller device such as a color printer or printer driver software installed in a computer. .
[0002]
[Prior art]
In recent years, functions such as color DTP and word processor have been enhanced, and not only text but also complex figures can be easily created. In particular, the gradation function is one of functions often used to improve the appearance of a document. As the gradation function, various gradation patterns are prepared as shown in FIG. 9, and a color at a predetermined end point is designated, and the area is painted so as to gradually change from designated color 1 to designated color 2. There are many (FIG. 10).
[0003]
In addition to the rectangle, the shape of the region includes a shape corresponding to a complex shape such as a polygon as shown in FIG. 11 and a shape that performs circular gradation processing. For example, an apparatus described in Japanese Patent Application Laid-Open No. 9-307740 performs gradation processing on a shape other than a rectangle, and divides the gradation region into a plurality of regions according to the shape of the region, and for each divided region. Various gradations are realized by setting the composition ratio of two colors.
[0004]
Furthermore, advanced gradations that specify not only end points but also intermediate points have been processed for designated points.
[0005]
The technology described in the above publication mainly considers application to a color copying machine. On the other hand, the invention described in JP-A-8-72317 is intended for gradation printing in a color printer. In the present invention, in order to improve the speed reduction in the communication system, PDL (printer description information) suitable for gradation is transmitted to the printer and developed into a raster image on the printer side. That is, the host computer transmits intermediate information representing mask data describing a drawing area and background information including gradation information and the like, and performs rendering by analyzing gradation information on the printer side.
[0006]
[Problems to be solved by the invention]
FIG. 14 is a diagram for explaining gradation processing. When the operator instructs gradation drawing, the host PC notifies the drawing module of a gradation drawing command, and the drawing module interprets the gradation drawing command and draws the gradation on the display.
[0007]
A drawing command for creating a gradation generally specifies information such as color data of end points (Cs, Ce in FIG. 12), the shape of a region to be filled, and a filling pattern. The color information of the end point usually uses color values in the RGB color space except for special cases.
[0008]
When printing the above gradation, the host PC sends the same drawing command to the printer driver or printer controller. The driver or controller interprets the drawing command described above, renders the gradation, and outputs it to the printer. Since the printer is a subtractive color mixing system, it is finally mapped to the CMY or CMYK color space.
[0009]
In the technique described in Japanese Patent Laid-Open No. 8-72317 described above, when rendering operation is performed, the designated colors Cs and Ce are color-converted and mapped to Ps and Pe before creating a gradation. However, if this method is used, the color space used for rendering differs between when it is displayed on the display and when it is output to the printer, so colors that differ significantly from the gradation displayed on the display are output. End up.
[0010]
Such a problem will be described with reference to FIGS. FIG. 12 is a diagram for explaining how to determine a color when displayed on a display. Assume that the colors at both ends of the gradation are given by Cs and Ce, respectively. At this time, the host PC divides the area by a predetermined number of divisions. For example, when divided into 20, the drawing color C (i) of the first area is C (i). Red = i * (Ce.Red-Cs, Red) / 20 + Cs. Red
C (i). Green = i * (Ce.Green-Cs.Green) / 20 + Cs. Green
C (i). Blue = i * (Ce.Blue-Cs.Blue) / 20 + Cs. Blue
(FIG. 13 (a)).
[0011]
When the above rendering process is performed after conversion to the printer signal (CMY), the specified colors Cs and Ce are first color-converted to obtain Ps and Pe, and then P (i). Cyan = i * (Pe.Cyan-Ps.Cyan) / 20 + Ps. Cyan
P (i). Magenta = i * (Pe. Magenta-Ps. Magenta) / 20 + Ps. Magenta
P (i). Yellow = i * (Pe. Yellow-Ps. Yellow) / 20 + Ps. Yellow
Thus, the drawing color Pi is obtained (FIG. 13B).
[0012]
In the above processing, since color conversion is performed with respect to the designated point in consideration of the characteristics of the printer, it is possible to make Cs and Ps and Ce and Pe substantially the same color. However, since the RGB color space and the CMY color space are in a non-linear relationship, the intermediate colors Ci and Pi obtained by the rendering process cannot guarantee the same color.
[0013]
As a result, a phenomenon occurs in which the gradation displayed on the monitor and the gradation output to the printer are greatly different. As a method for solving this, a method of performing color conversion to CMY (K) for each pixel after rendering processing in the RGB color space is conceivable. In this case, color conversion processing is performed for all pixels. Therefore, the processing time is significantly increased.
[0014]
The present invention has been made to solve the above problems,
An object of the present invention is to provide a color image output method, apparatus, and recording medium for printing a gradation faithful to a monitor screen at high speed.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a drawing area designated by a command in a document image, color signal values of a plurality of points designated in the drawing area, and the area designated A color image output method for generating a gradation image in the region based on a predetermined gradation pattern, wherein a color signal value between the plurality of points is divided into a predetermined number, and each divided point A first color list including the color signal values of the first color list is generated, and the color signal value of each point in the first color list is converted into a color signal value of another color system, thereby generating the second color list. When generating and rasterizing the drawing area, the second color list is referred to for each pixel in the drawing area, and the color signal value read from the second color list corresponding to each pixel is used. It is characterized by developing a gradation image into a bitmap .
[0016]
According to a second aspect of the present invention, it is determined whether or not black generation is performed for each section divided by the plurality of points. When it is determined that black generation is performed, the section is color-converted into four colors of CMYK. When it is determined that black generation is not performed, the section is color-converted into three colors of CMY .
[0017]
In a third aspect of the present invention, a drawing area designated by a command in a document image, color signal values of a plurality of points designated in the drawing area, and a predetermined gradation pattern designated in the area A color image output device for generating a gradation image in the region based on the first color signal value divided into a predetermined number of color signal values between the plurality of points, and comprising a color signal value at each of the divided points. Means for generating a color list of the first color list, means for converting the color signal value of each point in the first color list into a color signal value of another color system, and storing the converted second color list And means for referring to the second color list for each pixel in the drawing area when rasterizing the inside of the drawing area, and a color signal value read from the second color list corresponding to each pixel And means for developing a gradation image into a bitmap using .
[0018]
According to a fourth aspect of the present invention, there is provided means for determining whether or not black generation is performed for each section divided by the plurality of points, and when it is determined that black generation is performed, the section has four colors of CMYK. It is characterized by further comprising means for performing color conversion and means for performing color conversion in the section to three colors of CMY when it is determined not to generate black ink.
[0019]
The invention described in claim 5 is a computer-readable recording medium recording a program for causing a computer to implement the color image output method described in claim 1 or 2 .
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
(Example 1)
FIG. 2 shows a configuration example of a printing system when rendering processing is performed in the printer controller. Usually, the operating system 22 includes a dedicated module 23 for drawing, and this drawing module 23 manages drawing processing for a display and a printer.
[0021]
For example, when the operator prints a document image edited on the screen using a certain application 21 on a printer, the application 21 transmits a command to start a print job to the drawing module 23. Upon receiving a print start message, the drawing module 23 converts the document image data created by the application 21 into a command that can be interpreted by the printer driver 24, and transmits the command to the printer driver 24. The printer driver 24 converts the command received from the operating system 22 into a drawing command that can be interpreted by the printer controller 25 and transmits the command. A rendering device (interpret commands and convert to bitmap data) 26 and a color converter (convert RGB signals to CMYK signals) 27 of the printer controller 25 can perform image processing such as color conversion and output by the printer. Bitmap development 28 is performed on the raster image, pseudo gradation processing 29 is performed, and a printing operation is started.
[0022]
FIG. 1 shows the configuration of the first embodiment of the present invention, and shows the detailed configuration of the rendering device 26 and the color conversion device 27 in FIG. In the figure, 1 is a print command interpretation unit that interprets a drawing command, 2 is a color list generation unit that generates a color list from designated color data in a drawing command, 3 is a color list storage device that stores a color list, and 4 is a color A color conversion module for converting the list into a color signal for a printer, 5 is a color list storage device for storing the color list after color conversion, and 6 is a rasterization processing device for developing a gradation pattern into a bitmap in a drawing area.
[0023]
The gradation output operation in this embodiment will be described with reference to FIG. First, upon receiving a gradation drawing command, the printer driver converts it to another gradation drawing command (print command) that can be interpreted by the printer controller, and transmits it to the controller.
[0024]
The gradation drawing command includes parameters relating to the designated color data and drawing method normally specified by the operator. When the printer controller receives this gradation drawing command, it executes processing in the following steps.
[0025]
FIG. 3 is a process flowchart of the first embodiment of the present invention. First, the print command is interpreted (step 101), and a color list is created based on the designated color data (step 102). Next, the color list is converted into a color signal for the printer (step 103), rasterization processing is performed using the color list after the color conversion, and the color list is developed in a bitmap memory (step 104). When the rasterizing process is completed, pseudo gradation processing is performed according to the number of gradations of the printer (step 105), and output to the printer (step 106).
[0026]
Hereinafter, each step described above will be described using specific examples. Here, a case where a circular gradation is applied along the radial direction from the center (for example, FIG. 11) will be described as an example.
[0027]
GradFill (Col [], COIN, DivNum, Rect, CIRCLE PATTERN) as a circular gradation output command
A drawing command is assumed.
[0028]
Here, Col [] is a list of designated color data given by RGB color values, ColN is the number of designated colors, DivNum is the gradation division number of gradation, Rect is a structure representing the area to which gradation is applied, CIRCLE -PATTERN is a constant indicating a circular gradation.
[0029]
The gradation from the center to the radial direction designates two colors, the center color and the outermost color. in this case,
CoIN = 2
Col [0] = (Rs, Gs, Bs)
Col [1] = (Re, Ge, Be)
And Also, the area between the center and the outermost frame is divided into 256 gradations (DivNum = 256). The area Rect is designated by a rectangular area that circumscribes the circle to be drawn. For example, when gradation is applied to a circle having a radius r centered at (Xo, Yo),
Rect = (Xo-r, Yo-r, Xo + r, Yo + r)
As shown, specify the coordinates of the upper left point and the lower right point.
[0030]
When the printer controller receives the drawing command, it starts the processing operations in steps 101 to 106 described above. In the first step 101, the command is decoded by the print command interpretation unit 1, and the designated color information and the number of gradation divisions are sent to the color list generation processing unit 2. The color list generation processing unit 2 creates a list of color data for 256 gradations according to the designated color information (designated color data, the number of designated colors) and DivNum (step 102). FIG. 4 is a process flowchart for creating a color list.
[0031]
It is desirable to create the color list so that it has the same gradation characteristics as that displayed on the display as much as possible. For example, when a gradation is drawn so as to change linearly between col [o] and col [1] when the display is displayed, the controller side also sets Col [o] to Col [1]. Create a color list that is linear between.
[0032]
That is,
CLISTA [i]. Red = i * (Re−Rs) / 255 + Rs
CLISTA [i]. Green = i * (Ge−Gs) / 255 + Gs
CLISTA [i]. A color list CLISTA described by RGB values as Blue = i * (Be−Bs) / 255 + Bs (i = 0, 1,255) is created and stored in the color list storage device 3.
[0033]
In step 103, the color list CLISTA read from the color list storage device 3 is color-converted by the color conversion module 4 to be converted into a color list CLISTB of the printer signal and stored in the color list storage device 5. Various methods such as an interpolation method have been proposed for color conversion, and the present invention is not particularly limited as to what method is used, but device independence considering the color reproducibility of the monitor and the color reproducibility of the printer. A color conversion system in which the dent color (for example, Lab) matches is desirable.
[0034]
In step 104, the color list converted into the printer signal is read from the color list storage device 5, and the rasterization processing device 6 performs rasterization processing. The rasterization process is an operation of interpreting a command and converting it into bitmap format data. In the present embodiment, the information that is the basis of the rasterizing process is the color list CLISTB, the number of gradations DivNum, the drawing area Rect, and the gradation pattern CIRCLE PATHTERN. Hereinafter, rasterization processing using these pieces of information will be described.
[0035]
FIG. 5 shows a method for rasterizing a circle. A circle is drawn in a rectangular area defined by the area Rect. Draw a gradation here. In the rasterizing process, the drawing color is determined by searching corresponding points from the color list CLISTB for each pixel while sequentially scanning the inside of the rectangle.
[0036]
That is, the drawing color determination method for the coordinates (Xp, Yp) can be expressed by the following equation.
The distance d from the center point is obtained by d = SQRT ((Xo−Xp) 2 + (Yo−Yp) 2). When d> r, the pixel value is not changed. When d <= r, the drawing color P (Xp, Yp) obtained by the drawing color P (Xp, Yp) = CLISTB [int (255 * d / r)] is used as the pixel value.
[0037]
FIG. 6 is a diagram for explaining the color determination of the pixel of interest (Xp, Yp). When int (255 * d / r) = k, CLISTB [Ck, Mk, Yk] stored at the position of i = k is read out, and this is read as the drawing color P (Xp, Yp) of the pixel of interest (Xp, Yp). Yp).
[0038]
In the above method, since the color conversion is performed only on the color list CLISTA obtained by interpolating the designated color, the gradation displayed on the display can be faithfully reproduced.
[0039]
In the above-described embodiment, a circle gradation pattern has been described as an example. However, the present invention is not limited to this, and other shapes can be reproduced with a faithful gradation on a display by creating a color list in the same procedure. Can be created. Further, the color designated by the user is not limited to two colors, and a color list can be created according to the processing procedure of FIG. 4 even when there are three or more colors.
[0040]
(Example 2)
In the first embodiment, during the rasterization process, the color list CLISTB after color conversion is searched, and the color data corresponding to the target pixel is used as the drawing color as it is. However, in this case, unless the number of gradation divisions is significantly increased, tone jump may occur and the smoothness of the image may be impaired.
[0041]
Therefore, in this embodiment, the gradation property is improved by performing the rasterization process by performing the interpolation process shown in FIG. FIG. 7 shows a configuration of a rasterization processing apparatus according to the second embodiment.
[0042]
That is, in the rasterization method of the second embodiment, after obtaining the color list CLISTB by the same procedure as that of the first embodiment, the pixel value of (Xp, Yp) is obtained by the following procedure.
[0043]
The rate and idx calculation unit 31 calculates the area idx on the color list including the pixel of interest (Xp, Yp) and the internal division rate for interpolation calculation, and the interpolation calculation list and data extraction unit 32 calculates the color list. Interpolation calculation color data P [idx] and P [idx + 1] are read from the storage device 5, and the interpolation calculation unit 33 performs linear interpolation processing on P [idx] and P [idx + 1] according to the rate to determine the pixel value. To do.
[0044]
For example, in the rasterizing process for the circle in the first embodiment, d is obtained by the distance d = SQRT ((Xo−Xp) 2 + (Yo−Yp) 2) from the center point. If d> r, the pixel value is It does not change. When d <= r, idx = int (255.0 * d / r)
rate = (255.0 * d / r) -idx
Thus, the corresponding area on the color list and the internal ratio are obtained. Next, the drawing color is obtained by linear interpolation as the drawing color P (Xp, Yp) = rate * CLISTB [idx] + (1.0−rate) * CLISTB [idx + 1].
[0045]
In the above example, (idx + 1) is used as a region in the vicinity of the region idx, but other regions, for example, (idx-1) may be used as long as they are in the vicinity.
[0046]
(Example 3)
When a gradation is printed by a four-color (CMYK) printer, there may be a phenomenon that the image quality deteriorates when the ink combination is changed in the middle of the gradation. For example, when a gradation that changes from red to blue is created, the saturation is lowered at an intermediate portion of the gradation. As a result, K ink is not applied even in CMYK decomposition in high chroma portions such as red and blue, but K ink is mixed in low chroma portions.
[0047]
For this reason, when output is performed by a printer having particularly low gradation reproduction capability, the graininess is extremely deteriorated in the vicinity of the boundary where K ink (black) begins to mix. In this embodiment, a smooth gradation is output by adaptively changing the color conversion method according to the designated color of the gradation.
[0048]
The operation of the third embodiment will be described with reference to FIG. In this embodiment, two types of color conversion modules, a module 41 that performs color conversion to CMYK four colors and a module 43 that performs color conversion to CMY3 colors, are provided, and a color conversion mode determination unit 42 is provided.
[0049]
When the printer controller receives the gradation drawing command, the designated color data is converted into CMYK using the four color conversion module 41. Next, the color conversion mode determination unit 42 determines whether or not K ink is used. That is, for each section divided by a plurality of points, it is determined whether or not the points at both ends of the section use K ink.
[0050]
If neither of the points at both ends uses K ink, the module 43 is selected so as to perform color conversion in the three-color mode of CMY, and one of the points at both ends uses K ink. If it is, the module 41 is selected so as to perform color conversion in the CMYK four-color mode within the section, rendering processing is performed, and the result is output to the printer.
[0051]
The rendering process is preferably performed using a color list in the same manner as in the first embodiment, but a conventional rendering process may be used.
[0052]
Note that the processing of each of the above embodiments may be recorded as a program on a recording medium such as a CD-ROM, and this may be processed by software within the printer driver.
[0053]
【The invention's effect】
As described above, according to the present invention, a gradation faithful to the image displayed on the display can be generated at high speed and printed out. In addition, since the color conversion mode of the printer signal is switched while determining whether or not to generate black for each section delimited by the point data, the black ink is not applied only during the gradation, and a smooth gradation is achieved. Can be output.
[Brief description of the drawings]
FIG. 1 shows a configuration of Embodiment 1 of the present invention.
FIG. 2 shows a system configuration example to which the present invention is applied.
FIG. 3 is a process flowchart of Embodiment 1 of the present invention.
FIG. 4 is a process flowchart of color list generation.
FIG. 5 is a diagram for explaining a circle rasterizing method;
FIG. 6 is a diagram for explaining color determination of a pixel of interest (Xp, Yp). FIG. 7 shows a configuration of Example 2 of the present invention.
FIG. 8 shows a configuration of Embodiment 3 of the present invention.
FIG. 9 shows an example of a gradation pattern.
FIG. 10 shows an example of setting a designated color.
FIG. 11 shows an example of gradation for a shape other than a rectangle.
FIG. 12 is a diagram illustrating gradation rendering.
FIGS. 13A and 13B show the relationship between a designated color and a gradation drawing color.
FIG. 14 shows a configuration of gradation processing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Print command interpretation part 2 Color list production | generation process part 3, 5 Color list memory | storage device 4 Color conversion module 6 Rasterization processing apparatus

Claims (5)

The gradation in the area is based on a drawing area specified by a command in the document image, color signal values of a plurality of points specified in the drawing area, and a predetermined gradation pattern specified in the area. A color image output method for generating an image, wherein color signal values between the plurality of points are divided into a predetermined number, and a first color list including color signal values at each of the divided points is generated, When the second color list is generated by converting the color signal value of each point in the first color list into a color signal value of another color system, and when the inside of the drawing area is rasterized, A color image output characterized in that the second color list is referred to for each pixel and a gradation image is bitmap-developed using color signal values read from the second color list corresponding to each pixel. Method. It is determined whether black generation is performed for each section divided by the plurality of points. When it is determined that black generation is performed, the section is color-converted into four colors of CMYK and black generation is not performed. 2. The color image output method according to claim 1 , wherein when the determination is made, the inside of the section is color-converted into three colors of CMY . The gradation in the area is based on a drawing area specified by a command in the document image, color signal values of a plurality of points specified in the drawing area, and a predetermined gradation pattern specified in the area. A color image output device for generating an image, wherein the color signal values between the plurality of points are divided into a predetermined number, and a first color list including the color signal values of the divided points is generated; Means for converting the color signal value of each point in the first color list into a color signal value of another color system, means for storing the converted second color list, and in the drawing area When the image is rasterized, the gradation image is bit-converted using means for referring to the second color list for each pixel in the drawing area and a color signal value read from the second color list corresponding to each pixel. A color image output device comprising means for developing a map. Means for determining whether or not to generate black for each section divided by the plurality of points; means for converting the color of the section into four colors of CMYK when it is determined to generate black; and black generation 4. The color image output apparatus according to claim 3 , further comprising means for converting the inside of the section into three colors of CMY when it is determined not to perform the operation. A computer-readable recording medium on which a program for causing a computer to realize the color image output method according to claim 1 is recorded.

Images