JPH04102852A - Method and device for recording color image - Google Patents

Abstract

PURPOSE:To allow the checking of image quality in the state of simulating the thinning of dots at the time of printing with images for proofing by forming thinning simulation dot signals by logical computation of thinning simulation signals and dot signals for each respective plates. CONSTITUTION:This device consists of a color scanner 100 and an image recorder 200 for proofing. The digital image signals sy, sk, sym, sc are applied from the color scanner 100 to the image recorder 200 for proofing which converts the image signals sy1, sk1, sm1, sc1 correction by a color computing circuit 202 to the dot signals sdy, sdk, sdm, sdc and further inputs these signals respectively to a thinning simulation signal synthesizing circuit 204. These signals are added to the thinning simulation signals simulating the thinning of the dots and the thinning simulation dot signals sdy1, sdk1, sdm1, sdc1 are outputted. The images for proofing are recorded in accordance with these signals. The image quality is checked in the state of simulating the thinning of the dots at the time of printing by the images for proofing.

Description

[Detailed description of the invention]

[Industrial Application Field] This invention records a color image in halftone dot format on a light-sensitive material such as a photographic film based on image signals of a plurality of color-separated images obtained by color-separating a color original image. METHODS AND APPARATUS THEREOF. (Prior Art) When printing a color image, it is common to create a proofing image to check the quality of the printed image before the final printing process. In the conventional simple calibration method, yellow (Y), magenta (M), cyan (C), black (K
) was created, and the images for proofing were created by printing each mesh image one after another on color photographic paper specifically for proofing. (Problem to be Solved by the Invention) However, in the conventional simple calibration, it is necessary to create a color separation mesh image film for each dose, and when re-separation is instructed by the calibration judgment, the color separation mesh Image film is wasted. Furthermore, it is not possible to imitate the fading of halftone dots during printing (tiny spots on printing paper where ink does not adhere to the inside of the dots where ink should be applied). There was a problem that the image quality of the images differed. The present invention was made in order to solve the above-mentioned problems in the prior art, and an object of the present invention is to provide a color image recording method that can simulate halftone dot fading during printing, and an apparatus therefor. do.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the color image recording method according to the present invention includes: (a) a plurality of blurrings each simulating the blurring of halftone dots in a plurality of color separated images during printing; Prepare a simulated signal, (b) Based on the plurality of image signals,
A plurality of halftone signals each representing each color separation image as a halftone image are created, and (c) a plurality of halftone signals corresponding to each of the plurality of color separation images are generated by logically adding the halftone signal and the blurring simulation signal. (d) A color image is recorded based on the plurality of blurred simulated halftone dot signals. In this method, as each blur simulation signal corresponding to each color separation image, multiple types of original blur simulation signals are prepared depending on the presence or absence of halftone dots of other color separation images that are preprinted on each color separation image during printing. At the same time, when logically adding the fading simulation signal and the halftone dot signal, at each pixel position in the recording of a color image, the above-mentioned dots are added according to the presence or absence of halftone dots of other color separation images that are preprinted on each color separation image. It is preferable to select and use a plurality of types of original fade simulation signals. Further, the plurality of blur simulating halftone dot signals are first to fourth blur simulating signals corresponding to each color separation image of yellow magenta, cyan, and black in the order of two, and the recording of the color image is performed by (di) the above-mentioned By calculating the logical sum or AND of each of the first to third blurred simulated dot signals and the fourth blurred simulated halftone signal, the yellow plate and the black plate, the magenta plate and the black plate, and (d2) creating first to third composite halftone signals representing the union of halftone dots for each combination of the cyan plate and the black plate; It is preferable to record a color image on a photosensitive material by controlling the exposure beam based on the photosensitive material. Further, the color image recording device for carrying out the above-described method includes halftone signal generation means for creating a plurality of halftone signals representing each color separation image as a halftone image, based on the plurality of image signals; A plurality of blur simulation data each simulating blurring of halftone dots in the plurality of color separation images at the time of printing are stored, and a plurality of blurring simulation signals corresponding to the plurality of blurring simulation data are generated, a blurring simulating signal synthesizing means for creating a plurality of blurring simulating halftone dot signals corresponding to each of the plurality of color separation images by logically adding the signal and the blurring simulating signal; and recording means for recording a color image based on the signal. In this apparatus, each blurring simulation signal synthesizing means corresponding to each color separation image generates a plurality of types of original blurring simulation signals corresponding to the presence or absence of halftone dots in other color separation images that are preprinted on each color separation image at the time of printing. a plurality of original blur simulating signal generating means each generating a plurality of original blurring simulation signals; It is preferable to include a logical addition means for selecting one of the blur simulating signals and logically adding the selected original blur simulating signal and the halftone dot signal. Further, the plurality of blur simulating halftone signal synthesizing means combine first to fourth blur simulating signals corresponding to the respective color separation images of yellow magenta, cyan, and black with the respective halftone signals. between the first to fourth blur simulating signal synthesizing means and the recording means, each of the first to third blur simulating halftone dot signals and the fourth blur simulating By calculating the logical sum or logical product with the simulated halftone dot signal, the sum of halftone dots for each combination of the yellow plate and the black plate, the magenta plate and the black plate, and the cyan plate and the black plate is represented. The recording means is equipped with a black plate signal synthesizing means for creating the first to third synthesized halftone signals, and the recording means controls the exposure beam based on the first to third synthesized halftone signals. Preferably it is a means of recording a color image on the material. [Effect 1] Since a blur simulating halftone signal is created by logically adding the blur simulating signal and halftone dot signal for each plate, if a color image is created based on this blur simulating halftone signal, the blur of each plate can be can be simulated. In addition, halftone dot fading can be affected by the presence or absence of halftone dots on the pre-printing plate, so if you prepare multiple types of original fading simulation signals that correspond to this, it will be possible to use it under various overprinting conditions. It is possible to simulate cassoulet. Furthermore, the first halftone dot signal obtained by combining each of the faded simulated halftone dot signals of the Y, M, and C versions with the faded simulated halftone dot signal of the
Y if a color image is recorded on the photosensitive material based on the first to third composite halftone dot signals. It is possible to simulate not only the halftone dots of each version of M, C, but also the fading. Embodiment A. Structure and operation of the apparatus FIG. 1 is a diagram showing the structure of a scanner system as an embodiment of the present invention. This scanner system includes a color scanner 100 and a proofreading image recording device 200. The color scanner 100 is equipped with an input drum 101 and an output drum 102. The input drum 101 has a color original image OF, and the output drum 102 has a recorder for recording a halftone image obtained by color separation. Each film RF is wound. When reading the original image data by scanning the original image OF,
The input drum 101 rotates at a constant speed in the O direction, and the scanning head 103 is driven by the feed screw 104 at a constant speed in a direction parallel to the rotation axis of the input drum 101. Light emitted from a light source (not shown) provided inside the input drum 101 is received by the scanning head 103 after passing through the transparent input drum 101 and the color original image ○F. Blue light (B) focused by the scanning head 103
, green (G), and red (R) components are reflected by two dichroic mirrors 105a, 105b and one reflecting mirror 105c, respectively. The three reflected lights are individually converted into electrical signals by a photomultiplier tube 106, and then converted into blue, green, and red concentration signals Sb, Sg, and Sr by amplifiers 107a to 107c, respectively. These density signals Sb, Sg, Sr are sent to the masking circuit 1o8.
Here, they undergo processing such as color correction and gradation conversion, and are converted into image signals Sy, Sk, Sm, and Sc representing color-separated images of Y, M, and 0 versions, respectively. Image signal S
y, Sk, Sm, and Sc are converted into digital signals by the A/D converter 109 and provided to the dot generator 110. The digital image signals sy, Sk, Sm, Sc are
For example, it is a gradation level signal that expresses 256 gradations with 8 bits. When recording halftone images of Y, M, and C versions on recording film RF, dot generator 110 generates halftone dot signals Sd based on image signals Sy, Sk, Sm, and Sc. This halftone signal Sd modulates an AOM (acousto-optic modulator) 111 to turn on/off the laser light emitted from the laser light source 112. The laser light that has passed through the AOMI 11 is focused by the recording head 13 and exposes the recording film RF wound around the output drum 102. As a result, halftone images of each of the Y, K, M, and C versions are recorded on the recording film RF. Note that during this recording operation, the output drum 102 rotates at a constant speed in the O direction, and the recording head 113 is also driven by the feed screw 114 at a constant speed in a direction parallel to the rotation axis of the output drum 103. When creating a calibration image, the digital image signal Sy
, Sk, SmS Sc are given to the calibration image recording device 200 from the color scanner lOO. The calibration image recording device 200 includes an interface circuit 20
1, a color calculation circuit 202, and a dot generator 203
20 to the faded simulation signal synthesis circuit 204y, 204,
4m, 204c and K version signal synthesis circuit 205y, 205
m, 205c, laser light sources that emit laser beams of B, G, and R colors (not shown), and AOMI-knits 206y, 206m that control on/off of the laser beams of each color.
206c, a reflecting mirror 207a, a dichroic mirror 207b1207c, an exposure lens 208, and a drum 209. In the calibration image recording device 200, the digital image signals Sy, Sk, Sm, and Sc are transmitted to the interface circuit 20.
1 to the color calculation circuit 202. This color calculation circuit 202 calculates each digital image signal SyS S so that the color tone of the calibration image matches the color tone of the image on the printed matter.
It has a function of performing color correction and gradation correction for k, Sm, and Sc. Image signals sy1 and Skl corrected by the color calculation circuit 202
, Sml, Sc] are input in parallel to the dot generator 203 for four channels to generate halftone dot signals Sdy, Sdk.
, Sdm, and Sdc. These halftone signals 5d
yX 5dkS Sdm. Sdc is the recording film RF on the output drum 102
Y, recorded in , represents a shape similar to the shape of the halftone dot in the halftone image of each M and C version. For example, in each scanning line, the pixel position on the halftone dot is at L level, and the halftone This signal is at H level at pixel positions that are not on a point. In this embodiment, since the color sensitive material is exposed simultaneously using 10 exposure beams as described later, each halftone signal S
dy, 'Sdk, Sdm, and Sdc are each configured as a 10-bit signal that controls 10 exposure beams. Note that the screen line number and screen angle of the halftone image for each of the Y, K, and M%C versions are set to predetermined values by the dot generator 203, respectively. A method for arbitrarily setting the screen line number and screen angle of a halftone image is described in, for example, Japanese Patent Laid-Open No. 556393 and Japanese Patent Laid-Open No. 6
It is described in detail in Japanese Patent No. 1-137473. The halftone dot signals Sdy, Sdk, Sdm, and Sdc are generated by blur simulation signal synthesis circuits 204y, 204k, 204m, and 20
4c, and are added here with a blurred simulation signal simulating blurred halftone dots to produce 10-bit blurred simulated halftone dot signals 5dyl, 5dkl, Sdml,
It is output as 5dcl. The configuration and processing contents of the scratch simulating signal synthesis circuit will be further described later. Chromatic blur simulated halftone dot signal 5dy1. Sdm1.5d
Each of cl is a blurred simulated halftone dot signal 5dkl of the K version.
Along with the plate signal synthesis circuits 205y, 205m, 205
c. The plate signal synthesis circuits 205y, 205m, and 205C are as follows:
By calculating the logical sum or logical product of the two input signals, a composite halftone signal 5dy2 . Sdm2,5dc
Create 2. As a result, in the area that should be the K halftone dot, all three colors Y, M, and C develop into black, and halftone dots of the four colors Y, M, C, and K are recorded on the color photosensitive material. be able to. The configuration and processing contents of the K version signal synthesis circuit are detailed in Japanese Patent Application No. 1-285823, filed by the present applicant. Each of the 10-bit composite halftone dot signals 5dy2 . S
dm2, 5dc2 are AOM units 206y, 206
m, 206c, respectively. Note that the AOM units 206y, 206m, and 206c each include an AOM with 10 channels, and control the on/off of 10 exposure beams. In addition, AOM unit 20
6y, 206m, and 206c are blue-green and red exposure beams B and G, respectively. Control R. AOM unit 206. y, 206m,
Exposure beams B and G modulated with 206G. R is apparently combined into 10 beams by dichroic mirrors 207a to 207c, and the exposure lens 20
The color photosensitive material PF wound on the drum 209 is exposed with light condensed by the color photosensitive material PF, and a calibration image is recorded on the color photosensitive material PF. Note that during this exposure, the drum 209 rotates at a constant speed in the φ direction and moves at a constant speed in a direction parallel to the rotation axis. As described above, in this scanner system, the blur simulating halftone dot signals 5dyl and 5dkl, which simulate the fading of halftone dots during printing, are sent to the blur simulating signal synthesis circuits 204y and 204 by 204m and 204c. Since Sdml and 5dcl are created and a calibration image is recorded based on these signals, there is an advantage that the image quality can be confirmed in the calibration image while simulating halftone dot fading during printing. Further, K version signal synthesis circuits 205y and 205m. 205c, an image signal 5dy2. Since Sdm2゜5dc2 is created, for example, like silver halide photographic material, Y, M,
Even on an output medium having only CQ color layers, a calibration image can be directly recorded based on these signals. The above processing has the advantage that it is not necessary to record a color separation image on a screen film or the like in order to create a calibration image as in the conventional method, and the calibration image can be created directly from the image signal. In addition, Y is generated by the fading simulating signal synthesis circuit. After creating blurred simulated halftone dot signals for each of the M, C, and K versions, the K version signal synthesis circuit combines the faded simulated halftone dot signals of the other versions with the faded simulated halftone dot signals of other versions. , M, C, the principle by which the blurring of each edition can be accurately simulated will be explained in detail later. B. Processing details of the scratch simulating signal synthesis circuit B-1. Configuration and operation of blur simulating signal simulating acid circuit FIG. 2 is a block diagram showing the internal structure of the blur simulating signal synthesis circuit 204y for the Y version. The configuration of other versions of the blur simulating signal synthesis circuit will be described later. The blur simulation signal synthesis circuit 204y includes a blur simulation signal generation circuit 41y and a logic addition circuit 42y. The scratch simulating signal generation circuit 41y is a clock oscillator 410.
, an address counter 420, a line ring counter 430, and scratch simulation data memories 440 to 449,
Comparators 450 to 459 are provided. The logic addition circuit 42y also includes OR gates 460-469, NOR gates 470-479, and switch circuits 480-489. The fading simulation data memories 440 to 449 store fading simulation data Db that simulates fading of halftone dots. FIG. 3 shows an example of the blurring simulation data Db, and is a perspective view showing a three-dimensional histogram representing the level of the blurring simulation data Db of each pixel. This blur simulation data Db is configured as 4-bit data for each pixel in a 40x40 pixel matrix. Such fade simulation data Db is prepared for each version. 1
The blur simulation data memory 440 stores blur simulation data Db on four main scanning lines whose sub-scanning coordinates X are 1.11 and 21.31. Similarly, the second blur simulation data memory 441 stores blur simulation data Db on four main scanning lines whose sub-scanning coordinates X are 2.12 and 22.32. The same applies to the other memories 442 to 449. In addition,
The method for creating the blurred simulation data Db will be described further later. FIG. 4 is an explanatory diagram showing a comparison of the sizes of the pixel matrix PM for the blurred simulation data Db and the 100% halftone dot area HD. Here, the 100% halftone dot area is an area that is a repeating unit of halftone dots, and is an area occupied by halftone dots when the halftone dot area ratio is 100%. In this embodiment, taking the case where the screen angle is Oo as an example, the 100% halftone dot area HD is composed of 23x23 pixels. The cycle of the blur simulation data Db (40 pixels) is different from the cycle of the 100% halftone area HD (23 pixels). If the blur simulation data Db is regarded as a signal having a period of 40 pixels, and the data representing halftone dots is regarded as a signal having a period of 23 pixels, these two signals are asynchronous with each other. Moreover, the least common multiple of these periods is a value of 92020 pixels, and the degree of asynchrony is quite high. Note that, as will be described later, the fading simulation data is random data created on the assumption that fading of halftone dots occurs randomly. Therefore, the signal representing the blur simulation data is a random signal asynchronous to the halftone dot signal. Address counter 420 and line ring counter 430
is a circuit that outputs an address to be given to the scratch simulation data memories 440 to 449. The address counter 420 includes a clock signal oscillator 41
Along with the count clock signal Sac outputted from 0, a cylinder origin pulse Ps outputted from an encoder (not shown) provided on the shaft of the output cylinder 102 is given. This cylinder origin pulse Ps is a pulse signal that is generated one pulse each time the output cylinder 102 rotates once. The address counter 420 is cleared by this cylinder origin pulse Ps, counts the number of pulses of the count clock signal Scc, and outputs the result as a lower address La given to the blur simulation data memories 440-449. Address counter 420 is 4
It is a 0-base ring counter, and the value of the lower address La changes cyclically in the range of 0 to 39. This lower address La corresponds to the coordinates of the blur simulation data in the main scanning direction Y. On the other hand, the line ring counter 430 counts the number of cylinder origin pulses Ps and outputs the result as the upper address Ua of the blur simulation data memories 440 to 449. The line ring counter 430 is a quaternary ring counter, and the value of the upper address Ua is 0 to 3.
It changes cyclically within the range of . In other words, if expressed in binary numbers, the value of the upper address Ua is "00""01"
The upper address Ua is an address that specifies each of the regions R1 to R4 obtained by dividing the pixel matrix PM into four along the sub-scanning direction X, as shown in FIG. In the scanner system shown in the figure, a calibration image is recorded using 10 exposure beams, and each region R1 to R4 in FIG. 5 is an area that is exposed at once with each of the 10 exposure beams. When exposing R1, the fade simulation data Db for the area R1 is read out from the fade simulation data memories 440 to 449 according to the value of the upper address Ua. outputs the blur simulation data DbO on the main scanning line in which the coordinate value of the sub-scanning coordinate The blurring simulation data DbO to Db9 on each main scanning line, which is 10 from
0 to 459 respectively. Each comparator 450-4
59 is provided with a predetermined threshold value Dth together with blur simulation data Dbo-Db9. Each comparator 450-4
The output signals 5co-8c9 of No. 59 are at H level when each scratch simulation data DbO-Db9 is larger than the threshold value Dth, and are at L level when they are smaller than the threshold value Dth. 6A and 6B show the level of the signal 5c (ScO~5c9) when the value of the threshold Dth is the value A shown in FIG. 3, and the level of the signal Sc (ScO~5c9) when the value is B. FIG. In the figure, hatched pixels indicate that the signal Sc is at the H level, and white pixels indicate that the signal Sc is at the L level. A pixel for which the signal Sc is at H level is a pixel on which ink cannot be applied due to fading. Note that the value of the threshold Dth is set in advance by the operator so as to be able to simulate actual dot fading well, taking into consideration the unevenness of the printing paper and the amount of dampening water. Each 1-bit output signal S c of each comparator 450 to 459
O-S c 9 is applied to one input of each of OR gates 460-469 and NOR gates 470-479. OR gates 460-469 and NOR gates 470-
As the other input of 479, the dot generator 20
The halftone dot signal Ddy output from 3 is given. This halftone dot signal Ddy is a 10 bit signal corresponding to 10 exposure beams, and each bit of the signal is input to OR gates 460-469 and NOR gates 470-479, respectively. Output signals of OR gates 460 to 469 and NOR gate 4
The output signals 70 to 479 are the output signals of switch circuits 480 to 4.
89 respectively. Switch circuits 480-48
9 is switched according to a switching signal Ssl given from the outside. The switching signal Ssl outputs the output signals of OR gates 460 to 469 when recording the calibration image on a positive photosensitive material, and outputs the output signals of NOR gates 470 to 479 when recording on a negative photosensitive material. Switch circuits 480 to 489 are switched to . FIGS. 7A and 7B are timing charts showing the operation of the blur simulating signal synthesis circuit 204y when using a positive light-sensitive material and a negative light-sensitive material, respectively. In FIG. 7A and FIG. 7B, (a) is the faded simulation data Db.
is schematically shown and is expressed as a random noise component. The horizontal axis in the figure represents time, which is y in the main scanning direction.
corresponds to the pixel position (or address) of Threshold D
When th is set to the level shown in the figure, comparator 45
As shown in (b), the output signal Sc from 0 to 459 becomes H level only at pixel positions that satisfy Dth (Db).As shown in (C) of the figure, the halftone dot signal Sdy is output from the halftone dot forming part. This is a signal that becomes L level at
In each of the two signals Sdy. 5c (ScO to 5c9) are logically added, and (
A faded simulated halftone dot signal 5ay1 shown in d) is obtained. That is, at a pixel position where one of the two signals Sdy and Sc is at H level, the faded simulating halftone dot signal 5dy1 is at H level, and that pixel position is exposed. A positive photosensitive material is a photosensitive material in which exposed areas do not develop color and unexposed areas develop color. Correspondingly, the blurred simulated halftone dot signal 5dyl indicates that the pixel position where the blurred simulated signal Sc is at the H level is not colored but faded. When using a negative sensitive material, NOR gates 470 to 47
9, two signals Sdy, Sc (S
cO"5c9)) is inverted after logical addition, and the faded simulated halftone dot signal 5dy1 shown in (d) of FIG. only, fading simulated halftone dot signal 5d
y1 becomes H level, and that pixel position is exposed. A negative photosensitive material is a photosensitive material in which exposed areas develop color. Correspondingly, the blurred simulated halftone dot signal 5dyl shows that the pixel position where the blurred simulated signal Sc is at the H level is not colored but is also faded. The blurred simulated halftone dot signal 5dy1 synthesized in this way is output from the blurred signal synthesis circuit 204y, and is applied to the K version signal synthesis circuit 205M. In this way, the fading simulation data D as a random signal
b is stored in memory and read out and used in synchronization with the scanning when recording the proof image, so we can prepare fading simulation data for various printing conditions and use it to simulate fading according to the printing conditions. By rewriting the data, it is possible to successfully simulate fading under any printing conditions. Fig. 8A shows the fading simulation signal synthesis circuit 2 of Y, M, and C versions.
04y, 204m, and 204c, the block diagram shown in FIG. 8B is the K version blurred simulation signal synthesis circuit 204.
FIG. 2 is a block diagram showing a schematic configuration of the system. The circuit in FIG. 8A is drawn in a simplified manner; for example, the circuit 204y in the Y version of FIG. has been done. In addition, these faded simulating signal synthesis circuits are Y. This circuit generates an original blur simulating signal that takes into account the overlapping of each plate when the plates M and C are superimposed in this order. The reason why the overlapping of each plate is taken into consideration in this way is that the trapping rate of ink differs depending on the order of overlapping, and the manner in which fading occurs also differs. The M version blur simulation signal synthesis circuit 204m has the first and second
blur simulation signal generation circuits 41m1 and 41m2,
It has a switch circuit 43m and a logic addition circuit 42m. The first blur simulating signal generation circuit 41m1 generates a signal simulating the blur of a halftone dot on the M version when there is no halftone dot on the Y version below the halftone dot on the M version. The second blur simulating signal generation circuit 41m2 generates a signal simulating the blur of a halftone dot on the M version when there is a halftone dot on the Y version below the halftone dot on the M version. First and second blur simulation signal generation circuit 4
1m1.41m2 The signal generated from switch circuit 4
3m, which is switched by the Y halftone dot signal Sdy in the switch circuit 43m, and either one of the signals is applied to the logic adder circuit 42m. Note that the first and second blur simulation signal generation circuits 41 m, l, 41
Similarly to the blur simulating signal generation circuit 41y shown in FIG. 2, 10-bit signals corresponding to the 10 exposure beams are output from m2, and each of these signals is generated by the 10-bit halftone dot signal Sdy. They are independently switched and output. The signal output from the switch circuit 43m is logically added to the M-version halftone dot signal Sdm in the logic addition circuit 42m, and is output as a blurred simulated halftone signal Sdm1. The scratch simulating signal synthesis circuit 204C of version 0 also has the same configuration as the circuit of M version, and includes first to fourth blur simulating signal generation circuits 41c1 to 41C4, a switch circuit 43c, and a logic addition circuit 42c. have. Note that the symbols rY+], rM+], rC shown inside each scratch simulating signal generation circuit in FIGS. 8A and 8B
+] is the 7th edition 2M edition. Each of these circuits indicates that the circuit generates an original faded simulating signal corresponding to the case where the 0th edition is printed first. The M version is also used for the K version's fade simulation signal synthesis circuit 204. It has the same configuration as the circuit of version 0, and has 8 in the first to eighth blur simulation signal generation circuits 41, 8 in the switch circuit 43, and the logic addition circuit 42. There is. The switch circuit 43k is provided with output signals from eight blur simulation signal generation circuits 1 to 41, and
It is switched by the three halftone dot signals Sdy, Sdm, and Sdc and supplies its output signal to the logic adder circuit 42k. As shown in FIGS. 8A and 8B, if the original fading simulation signal is selected in consideration of the overlap of the halftone dots of each plate, the advantage is that fading including the influence of the ink trapping rate can be simulated. There is. B-2. Method for creating blurred simulated data The causes of halftone dot blurring are as follows. a, Dampening water left on the halftone dots of the printing plate (hereinafter referred to as "residual damp water") b, unevenness of the printing paper C0 ink absorption rate of the printing paper d, ink trapping rate e, printing Of these, the dominant factors for the occurrence of scratches are thought to be the influence of residual hot water and the unevenness of the printing paper. here,
The following three conditions are assumed regarding the mechanism of occurrence of halftone dot fading. Condition C1: If the occurrence of fading (non-transfer of ink) is considered as a stochastic process, the occurrence of fading is steady and ergodic. [Stationary J] regarding stochastic processes generally refers to the fact that the statistical properties of a stochastic process do not change even if the time is shifted, but here it means that the mode of occurrence of blurring does not change for different halftone images. . Furthermore, "ergodic" generally refers to the fact that the collective average of a stochastic process is equal to the time average of that stochastic process, but here it refers to an area that includes a certain number of halftone dots within the same halftone image. This means that the manner in which fading occurs within the halftone image is the same as the manner in which fading occurs within the entire halftone image=34=. Condition C2: The appearance of fading is white. This means that the occurrence of smudges is not concentrated in a specific part and there is no specific cycle. Condition C3: The occurrence of scratches on the printed paper surface is concentrated in the concave portions of the texture (weave of paper fibers). Here, furthermore,
It is assumed that the printed paper surface has a random texture. Random textures have some degree of periodicity based on the size (thickness and length) of the paper fibers. Furthermore, the residual hot water also has some periodicity. In other words, water droplets of a certain size tend to remain on the halftone dots, and water droplets that are too large or too small are difficult to remain on. Among the three conditions C1 to C3 above, conditions C1 and C
2 shows that the occurrence of blurring can be simulated as non-periodic white noise. On the other hand, condition C3 indicates that the occurrence of scratches can be simulated as a random signal with some degree of periodicity. Assuming conditions 01 to C3, the occurrence of dot fading can be simulated as a random signal having a spectrum uniquely estimated by the random texture of paper fibers and the size of residual hot water. At this time, the spectrum of the smear in the phase space can be estimated as a linear combination of the spectrum according to the fundamental frequency of the random texture (and/or the residual hot water) and the spectrum of the white noise. Regarding the estimation method of such a random signal,
For example, "Spectrum Analysis" by Mikinan Asakura (Breakfast Shoten,
(October 1977), page 142 onwards. An example of how to apply this method to create blurred simulated data will be described below. B-2a, Based on the estimation of the power spectrum (method) The power spectrum S (U, V) corresponding to the occurrence distribution of blurring G (x, y) is calculated using the following formula for estimating the power spectrum of a random signal. It is expressed as: S (U, V) = 4 (A' 2) ・ (B'
2) [1/fl (U)+1/f2 (U)+1/
f3 (V)+1/f4 (V)] fl (U)
=B”2+ (U+U (0)) “2(2
a) f2 (U) =B”2+ (U-U (0)
) '2(2b) f3 (V)=B"2+(V+V (0)) "2(2
c) f4 (V) =B” 2+ (V-V (
0)) ” 2... (2d) Here, the operator ' represents a power. Also, each sign is defined as follows. U, V: Cartesian coordinates U (p), V in the frequency plane (q) :U, v(7) Spectral samples in the domain [0, U(Nx)], [0, V (Ny)]. U(0) and V(0) are the This is the center frequency.Here, the center frequency is the frequency at which the spectrum has a peak.Here, we are considering the case where the coordinates U and ■ are equisymmetric, and U(○) = V (0 ). A, B: Coefficients that determine the shape of the power spectrum. The fading occurrence distribution G (x, y) in real space is expressed by the power spectrum S (U, V) as follows: G ( x, y) −4ΣpΣq (S (Upa, Vqa) (ΔUp・ΔVq) −0,5 1cos (Upa−x+θp) ・5in(Vqa−y+θk)) ・・(3) Upa−(U (p) 10 (p-1)) /2...
・(4a) Vqa= (V (q)+V (q-1)) /2・・
・(4b) 80p=U (p)-U (p-1) -(5a)Δ
vq=v (q)-V (q-1)-(5b) Here, operators Σp, Σq are scaled from zero to Nx for sign p.
An operation for adding up to Ny and an operation for adding from zero to Ny with respect to the sign q are shown respectively. Moreover, op and θq represent −-like random numbers. The fading occurrence distribution G (x, y
) represents the distribution shape of the blurred simulation data Db, and has a shape as shown in FIG. 7A (a) and FIG. 7B (a), for example. The fading simulation distribution G (x, y) has a center frequency U (
0) (=V (0)) and the values of coefficients A and B have different shapes. Therefore, these values U(0), A, B
As a parameter, several kinds of blurred simulated distributions G (x
, y) are created based on equation (3). At this time, the range of the value of the center frequency U (0) can be predicted to some extent from the manner in which blur occurs in actual halftone dots. In addition, assuming that the smudged simulated distribution G (X + y) is equal, the smeared simulated distribution G (X + y) is
All you have to do is find (x, y). The scratch simulation distribution G (x, y) obtained in this way is stored in the scratch simulation data memory 44 as the scratch simulation data Db.
0 to 449, and create a proofing image for solid painting. This calibration image includes Y, M, C,
A single image for each version of K, and images obtained by overprinting two, three, and four colors of these are prepared. Meanwhile, in parallel with this, a solid printing sample is prepared. As this print sample, Y. A printed matter in which M, C, and M plates are printed individually, and a printed matter in which two, three, and four colors of these are overprinted are prepared. The purpose of preparing various overprint samples of proof images and printed samples in this way is to prepare fading simulation data that reflects the differences in the way fading occurs depending on the characteristics of each ink and the way of overprinting. This is to create. Next, the calibration image created as above and the print sample are compared, and a blur distribution G (x, y) that can simulate the blur in the print sample with good reproducibility is selected, and this is used as the blur simulation data Db. Adopted as. In this way, the fading simulation signal generation circuits 41y, 41m1 to 41m2, 41c shown in FIGS. 8A and 88
The faded simulation data Db stored in the memory in 8 is obtained at l~41c4 and 41kl~41. B-2b. Method based on autocorrelation function of fading In this method, first, the above-mentioned solid print sample is created, and the distribution of occurrence of fading is actually measured. The two-dimensional distribution Ga(x, y) of scratches obtained through actual measurement is expressed as binary data representing the presence or absence of scratches for each pixel. The two-dimensional autocorrelation function (two-dimensional autocovariance function) φ of this Kasoulet distribution Ga (x. y)
(τX, τy) is given by the following equation. φ(τX, τy) = (1/σ”2) (1/L-2) ・ΣiΣj [(G (i, j)-gg) (G(i+τ
X, j tenτy) - gg) ]...(6a) σ ° 22 (1/L"2) ・ΣiΣj [(G (i, j) - gg)
" 2]... (6b) gg= (1/L" 2) ・ΣiΣj (G (i, j))
... (6c) Here, using the Wiener/Kinchin formula, the power spectrum of Kasoulet S (U, V
) and the autocorrelation function φ(τX, τy) are related by the following equation. S (U, V) −F [φ (τX, τ
y)]...(7) Here, operator F represents Fourier transform. From the power spectrum S (U.
x, y). This blurred simulated distribution G(x,
y) is the actually measured blur distribution G a (x + y
), it is expressed by multivalued data, and has a shape as shown in FIG. 7A (a), for example. The blur simulation signal generation circuit 41y uses this blur simulation distribution G (x, y) as the blur simulation data Db. 41m1~41m2, 41cl~41c4, 1 in 41~
By storing them in the memories 41 and 8, it is possible to simulate halftone dot fading. Note that the actually measured binary blur simulation distribution Ga (x, y) may be used as is as the blur simulation data Db. In this case, the comparator 45 of the configuration shown in FIG.
There is an advantage that 0 to 459 are not necessary. However, if the multi-value blurring simulation distribution G (x, y) obtained as described above is adopted as the blurring simulation data Db, the level of the threshold value Dth can be changed as explained in FIGS. 7A and 7B. This has the advantage that the size of the blur on the calibration image can be changed, and it becomes easier to simulate the actual occurrence of the blur. Synthesis processing by the C, version signal synthesis circuit FIG. 9 shows the K version signal synthesis circuit 205y, 205m, 20
FIG. 5 is a conceptual diagram showing the content of compositing processing in 5C. FIG. 9(a) shows how the halftone dots of each color of yellow (Y), cyan (C), and black (K) are printed one on top of the other in this order. For simplicity, it is assumed that there are no magenta halftone dots. In (b), (c), and (d) of Figure 9, C, K
. Blurred simulated halftone dot signals 5dcl and 5dkl for each Y version. A halftone dot represented by say 1 is shown. Three faded areas Hc] to Hc3 are simulated within the halftone dots of the 0 version, and similarly, four faded areas Hkl to Hk4 are simulated within the halftone dots of the 1 and K versions, and the halftone areas of the Y version are simulated. Three faded portions Hyl-Hy3 are simulated within the dots. (e), (f), and (g) in FIG. 9 show composite halftone dot signals 5dc2. Each halftone dot represented by Sdm2Sdy2 is shown. As can be seen from the figure, the composite halftone dot signals 5dc2, 5dy2 are 0
The shapes of the union of the halftone dots of the Y version and the K version are respectively shown. In addition, the composite halftone dot signal S d of the M version
The shape represented by m2 is the same as the halftone dot shape of the printing plate shown in (c), and this is overlapped with the halftone dots of the 0 and Y printing plates to form the halftone dots of the printing plate. FIG. 9(h) shows the above composite halftone dot signal S dy2°S
It shows halftone dots in a calibration image created based on dm2 and 5dc2. In this halftone dot, the third faded portion Hc3 of the 0 version and the third faded portion Hy3 of the Y version have disappeared. This is due to these scratched parts Hc3. Hy3
This is because the dots overlap with the halftone dots of the K version. Furthermore, since the halftone dots of the Y plate are present in the second faded portion Hc2 of the 0 edition, this faded portion Hc2 appears yellow. The four faded areas Hkl NHk4 of the K plate are all reproduced, but the second faded area Hk2 has cyan halftone dots, so it appears cyan (indigo 8). Similarly, the color of the third faded portion Hk3 appears to be yellow, and the color of the fourth faded portion Hk4 appears to be (yellow-cyan). In this way, the blur simulating halftone signal synthesis circuits 204y, 2
04, after simulating the fading of each halftone dot using 204m and 204c, the K version signal synthesis circuit 205y, 205m, 2
05c, blurred simulated halftone dot signal and Y, M, C
If you combine the fading simulated halftone dot signals of each version,
The resulting composite halftone signal 5dy2. Sdm2,5
Even in the calibration image created based on dc2, Y
. It can successfully simulate the blurring of M, C, and K versions. D. Modifications The present invention is not limited to the above embodiments, and the following modifications are also possible. (1) In the above embodiment, the calibration image was recorded on a silver halide photographic material in which colors are recorded by exposure of 83 colors of R, G, but various other printers (electrostatic type, Thermal transfer printers, thermal dye printers, inkjet printers,
A calibration image may be created using a laser printer, etc.). However, in these cases, directly Y, M, C
, K, Y, M since the image is recorded using subtractive color ink of four colors. The amount of ink of the four colors is controlled based on four dot signals simulating fading for each of the C and K versions. Therefore, it is not necessary to perform the process of adding the faded simulated halftone dot signal of the K plate to the faded simulated halftone dot signal of the chromatic color plate, as in the above embodiment. Furthermore, the present invention is applicable not only to the case where a color image is recorded using three colors of YMC or four colors of YMCK, but also generally to a method and apparatus for recording a color image using a plurality of colors. (2) Similar to halftone dot fading, dot gain during printing can be reproduced in the proof image. Here, dot gain refers to an increase (difference) in the halftone dot area ratio of a printed matter with respect to the halftone dot area ratio of a printing plate. To simulate the dot gain, use the simulated data as, for example, the first
This simulated data is stored in a memory (not shown) in the color calculation circuit 202 shown in the figure, and is used to increase the dot area ratio by the dot gain during tone correction processing performed in the color calculation circuit 202. Then, you can create a proofreading image. (Effects of the Invention) As explained above, according to the present invention, the blur simulating halftone signal is created by logically adding the blur simulating signal and the halftone dot signal for each plate, so that the blur simulating halftone signal is created based on this blur simulating signal. If a color image is created by using the same method, it is possible to simulate the fading of each plate. In addition, halftone dot fading may be affected by the presence or absence of halftone dots on the pre-printing plate, so if you prepare multiple types of original fading simulation signals that correspond to this, it will be possible to adjust the halftone dot fading under various overprinting conditions. This has the effect of being able to simulate the smearing caused by Furthermore, a first halftone dot signal obtained by combining each of the faded simulated halftone dot signals of the Y, M, and C versions with the faded simulated halftone dot signal of the
Y if a color image is recorded on the photosensitive material based on the first to third composite halftone signals. This has the effect that it is possible to simulate not only the halftone dots of each plate for M, C, but also the blurring thereof.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a scanner system as an embodiment of the present invention, FIG. 2 is a block diagram showing the internal configuration of a blur simulating signal synthesis circuit, and FIG. 3 is an example of blur simulating data. The histogram shown in Fig. 4 is a pixel matrix of blurred simulation data and 100
5 is an explanatory diagram showing the area into which the pixel matrix is divided, and Figures 6A and 6B are the comparison between the threshold level and the blurred simulated signal. 7A and 7B are conceptual diagrams showing the relationship, and FIGS. 8A and 8B are timing charts showing the operation of the blur simulating signal synthesis circuit.
FIG. 9 is a block diagram showing a schematic configuration of the blurred simulating signal synthesis circuit, and FIG. 9 is a conceptual diagram showing the content of synthesis processing by the K version signal synthesis circuit. Sdy, Sdk, Sdm, 5dc --- Halftone signal S d
y l , S d k 1 , S d m
1, Sdc41-fading simulated halftone dot signal

Claims (6)

[Claims] (1) A method of recording a color image in halftone dot format based on a plurality of image signals each representing the density level of each pixel of a plurality of color-separated images obtained by color-separating a color original image, the method comprising: ) preparing a plurality of blurring simulation signals each simulating blurring of halftone dots in the plurality of color separation images during printing, and (b) preparing each color separation image as a halftone image based on the plurality of image signals. (c) creating a plurality of blurred simulated halftone dot signals respectively corresponding to the plurality of color separation images by logically adding the halftone dot signal and the blurred simulated signal; (d) A color image recording method, characterized in that a color image is recorded based on the plurality of blurred simulated halftone dot signals. (2) The color image recording method according to claim 1, wherein each blur simulation signal corresponding to each color separation image is based on the presence or absence of halftone dots of other color separation images that are preprinted on each color separation image at the time of printing. In addition to preparing a plurality of types of original fading simulation signals corresponding to each of them, when performing the logical addition of the fading simulation signal and the halftone dot signal, at each pixel position in recording a color image, other types of original blurring simulation signals preprinted on each color separation image are prepared. A color image recording method in which the plurality of types of original blur simulation signals are selected and used depending on the presence or absence of halftone dots in a color-separated image. (3) The color image recording method according to claim 1 or 2, wherein the plurality of faded simulated halftone dot signals include a first halftone dot signal corresponding to each color separated image of yellow, magenta, cyan, and black in this order.
to a fourth blur simulating signal, and the color image is recorded by (d1) the logical sum or logic of each of the first to third blur simulating halftone dot signals and the fourth blur simulating halftone signal; By taking the product, the yellow version and the black version,
A first set representing the union of halftone dots for each combination of the magenta plate and the black plate, and the cyan plate and the black plate.
(d2) controlling the exposure beam based on the first to third composite halftone signals, thereby producing a color image in halftone format on the photosensitive material; Color image recording method. (4) A device for recording a color image in halftone dot format based on a plurality of image signals each representing the density level of each pixel of a plurality of color separated images obtained by color separation of a color original image, the plurality of halftone signal generation means for creating a plurality of halftone signals representing each color separation image as a halftone image based on the image signal of the second halftone image; A plurality of blur simulating data are stored, a plurality of blur simulating signals corresponding to the plurality of blur simulating data are generated, and the halftone dot signal and the blur simulating signal are logically added. The image forming apparatus is characterized by comprising a fade simulation signal synthesizing means for creating a plurality of blur simulation halftone dot signals respectively corresponding to the separated images, and a recording means for recording a color image based on the plurality of blur simulation halftone signals. Color image recording device. (5) The color image recording device according to claim 4, wherein each fade simulation signal synthesizing means corresponding to each color separated image is configured to combine halftone dots of other color separated images that are preprinted on each color separated image at the time of printing. A plurality of original blur simulating signal generating means each generating a plurality of types of original blur simulating signals corresponding to the presence or absence of the original blur, and a plurality of original blur simulating signal generating means each generating a plurality of types of original blur simulating signals corresponding to the presence or absence of the original blur, and a plurality of original blur simulating signal generating means each generating means for generating a plurality of types of original blur simulating signals corresponding to the presence or absence of the original blur. A color image recording device comprising: logical addition means for selecting one of the plurality of types of original blurred simulation signals according to the presence or absence of halftone dots, and logically adding the selected original blurred simulation signal and the halftone signal. (6) The color image recording device according to claim 4 or 5, wherein the plurality of faded simulating halftone dot signal synthesis means include first to first halftone dot signal synthesis means corresponding to each color separated image of yellow, magenta, cyan, and black in this order. first to fourth blur simulating signal synthesizing means for synthesizing the four blur simulating signals with respective halftone dot signals; and between the first to fourth blur simulating signal synthesizing means and the recording means, By calculating the logical sum or AND of each of the first to third blurred simulated dot signals and the fourth blurred simulated halftone signal, the yellow plate and the black plate, the magenta plate and the black plate, and black plate signal synthesis means for creating first to third composite halftone dot signals representing the union of halftone dots for each combination of the cyan plate and black plate; A color image recording apparatus is a means for recording a color image on a photosensitive material by controlling an exposure beam based on the composite halftone signal of No. 3.