JP2000134485A - Processing method for image information of color document information at time of production of color print image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system which is suitable for high picture quality, high output quality, and customer's needs as the processing method for image information of a color document image at the time of the production of a color print image. SOLUTION: This method is implemented through all of 'phases' which are discriminatingly sectioned and mutually relative, i.e., (1) a 'phase' for rearranging image information obtained from the color document image, (2) a 'phase' for designing process measures for the rearranged image information obtained in the process (1), (3) a 'phase' for processing the rearranged image information according to the design specifications of the process measures determined in the process (2), and (4) a 'phase' for applying the image information obtained in the process (3) to the production of a color copy image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color original image which is applied when a halftone color print image is reproduced (hereinafter also referred to as "production") from a continuous tone color original image. A new processing method for image information.

More specifically, the present invention takes into account the fact that the entire process and the entire system when producing a color print image from a color original image are extremely complicated, and in particular, color separation (separation / (I). In consideration of the complexity of the image processing system and elemental technology when performing color conversion, and the versatility of customer needs, etc., (i). The entire image processing system for producing color print images (overall "place") Are divided into several core "fields" (individual "fields" constituting the whole field described above), and (ii) for each "field", each "field"
Introduce the concept of "place" that incorporates (incorporates) technical means adapted to the characteristics (requirements) of each "place", etc. The present invention relates to a novel method of processing image information of a color document image which is a feature of the present invention.

[0003]

2. Description of the Related Art To produce a color print image of high quality, high image quality and halftone dot tone from a continuous tone color original image as shown in FIG. In order to perform the entire process (all systems) rationally and efficiently, there are extremely complicated and diverse check items and examination items, and items that need to be considered.

As shown in FIG. 1, even in a color original image itself to be processed, subsequent image information processing,
That is, color separation (this term is used for R / G /
This is used in a narrow sense that the color information of B is obtained after being separated. ) And tone conversion (this term means to convert and reproduce the gradation of a color original image on a duplicate image, and should be interpreted in a broad sense to include both tone and tone conversions) There are various considerations and issues that need to be considered in order to implement.

In the present invention, the technical means for processing the image information includes an image information processing technique, a color separation technique or a color separation processing technique (including both the above-described color separation and gradation conversion). ). Further, in the present invention, from the viewpoint that the image information processing technology applied to all systems for producing a color print image of a final product starting with the submission of a color original image must be a systematic, The information processing technology is also called an image information processing system. As a matter of course, the image information processing system is based on the premise that there are some lower subsystems.

As shown in FIG. 1, the image information processing system (color separation technology) rationally incorporates the needs of various audiences from the viewpoint of the finished condition of a color print image as a final product to achieve high quality. , High quality, and must meet the needs of the audience.

However, to date, it is no exaggeration to say that there is no systematic image information processing system applied to all systems (total systems) for producing the above-described color print images. .
That is, the image information processing technology applied at the time of the conventional color print image production is: image information processing technology of a very limited area in the entire system; It is not an exaggeration to say that when viewed from the viewpoint of the above, they have no organic relationship with each other or the organic relationship is extremely poor.

[0008] In connection with the above, even today's expensive image processing equipment (advanced mechatronics equipment), color that fully satisfies the desired high quality, high image quality, and audience needs. At present, it is not possible to produce printed images rationally and efficiently.

Recently, in image information processing technology, DTP
As seen in the above, with the opening of devices, there has been an increasing movement to build a device independent color management system (CMS). This was born from the intent of achieving unified color management regardless of the type of image information processing equipment used with the opening of related equipment for image information processing. . The construction of the color management (CMS) described above can be said to show one way in view of the fact that the problem of color consistency in the production of a color print image is an extremely large problem.

[0010] However, the CMS (color management system) approach is not well accepted in the market today. Hereinafter, the outline of the CMS approach will be described, but it should be understood that the difficulty and difficulty in producing a color print image rationally from this (the Journal of the Printing Society of Japan, Vol. 34, No. 5). , 1997
Year, see pages 320-325).

[0011] The CMS provides a function of perceiving an image to be the same to human vision among a plurality of devices (for example, an image input device, a monitor device, and an image output device). Can be defined. One method of realizing the above-mentioned CMS is a method in which tristimulus values between a document image and a duplicated (reproduced) image match between various devices having different color characteristics (color space, color space). There is. More specifically,
This method uses device values such as CMYK (or RGB) used in devices such as a scanner (image getter), monitor, and printer (image setter), and corresponding XYZ, Lab, L (star) a (star). This is a method of performing colorimetrically consistent color reproduction by mutual conversion with device-independent color values such as b (star). In other words, the color reproduction is performed by matching the color space (color space) unique to each device with a color space that is a reference (standard). That is, the above-mentioned method is to handle image data based on color values and to execute device-independent (device-independent) color management (CM).

In order to convert between the device values and the color values described above, the color characteristics of each device must be examined, and this must be described as data called a device profile. The format of the device profile is ICC (International
l Color Consortium). The IC
C is an organization set up in 1993 to realize and standardize a color management system (CMS) in an open environment. ICC members include Kodak, Agfa, Fuji, and Microso
It is made up of the world's leading color image-related companies such as ft, Adobe, and Apple, and standardization of ICC is about to become a virtual world standard.

The device profile of the ICC is:
Known as the ICC profile,
997 ICC Profile Format Specificatoin Vers
ion3.4 has been released and is available for download on the Internet homepage (www.Color.org).

The outline of a color management system (CMS) using the ICC profile is as follows. (1) The system configuration can be roughly divided into:-an image input device such as a scanner or a digital camera;-an image display device such as a monitor;-an image output device such as a printer; A system unit (which constitutes a part of the application unit) for performing color management. (2) Device profiles are classified into: an input profile (Input profile), a display profile (Display profile), and an output profile (Output profile), and the format of each is determined. (3) The color management (CM) is automatically executed when a color processing command is issued in the application unit, while the color management module (CMM) in the system is automatically called.

The color management system (CM)
The CMS in which the original is scanned in S), displayed on the monitor and output by the printer will be specifically described below.

(1). Color management module (C
MM) is the scanner profile, i.
The RGB values obtained by the image information reading mechanism of the scanner are converted into color values L (star) a (star) b (star) using the nput profile). When converting the RGB values into color values L (star) a (star) b (star), a fundamental tool (a fundamental) for the conversion is used.
tool) is ANSI (American National St.
andards Insititute) Standards Comi
ttee IP8. This is a standard manuscript (eg, IP 8.7 / 1 or 7/2) developed by Working Group. Each scanner (each input device) uses the above-mentioned standard original IT8.7 / 1 (transparent original, photographic film original)
Or 7/2 (reflective document) is scanned and input, and the reference color value L (star) a (star) from any document
A scanner profile (scanner profile) for obtaining b (star) will be prepared. (2) Next, the color values L (star) a (star) b (star) are converted into RGB values of the monitor by a monitor profile and displayed on the monitor. (3). Furthermore, a printer profile
Thus, the color values L (star) a (star) b (star) are converted into CMYK values of the printer and output on recording paper. By the above process, color reproduction by matching of color values, that is, color management (CM) in which color values L (star) a (star) b (star) match is realized.

However, a color management system (CMS) centered on the ICC profile
At present, there is not yet enough space to be found in the color-related industry, for example, in the field of color printing. The above-mentioned defects of the color management system (CMS) having the ICC profile as the core can be easily understood from the following points.

(1) A standard (standard) original, for example, a transparent original (photographic film original, transparency) serving as a standard is easily obtained from Fuji Photo Film (Fuji), Agfa (Agfa), Kodak (EK), or the like. However, these are considerably different from each other visually, and are different from each other even if the color is measured by a colorimeter. This is the current situation in the preparation of the reference manuscript, and the above points must be sufficiently taken into consideration when using the present system. In addition, the inventor described later in detail,
The photographic film photosensitive material used to create the transparency manuscript (transparency manuscript) has a unique photographic (density) characteristi
c curve), each reference document is also affected by its own photographic characteristic curve, and it is considered that the above-mentioned variation among the reference documents can easily occur.

(2). The ICC is used in a device (scanner profile generotors) for producing an input profile.
In order to improve the accuracy of MS, for example, the type of light source (for example, D50 having a color temperature of 5000 k) and measurement conditions (for example, an observation angle of 45 °) are specified. However, these conditions for improving the accuracy are usually extremely limited in view of human visual conditions when a human views a color image (subject, real scene). In other words, it is unlikely that a true color management system (CMS) will be constructed by matching the rich visual sensation of a human to such extremely limited conditions.

(3). The targets (standard manuscripts, ANSI 8.7 / 1, 7/2) recommended by the ICC include three segment patches: (i). Dye patches (dye scales), and (ii). It consists of three main elements: a neutral density patch (neutral dye scales), and (iii) a color gamut area. However, the color information (color information) included in these three elements is extremely limited as a reference for the actual color world. This point is also one of the major limitations of the color management system (CMS) based on the ICC profile.

As mentioned above, the ICC profile approach for a color management system (CMS) starts with the reference targets (a standard manuscript prescribed by the ICC) as a fundamental tool. . However, due to restrictions on this type of target, measurement conditions, and the like, at present, sufficiently satisfactory results have not been obtained among various devices in an open environment such as DTP.

As is clear from the above, in color reproduction technology,
An elemental technology for converting and compressing a color original image that sufficiently reflects human visual characteristics is indispensable. The approach of the color reproduction method based on the color value matching based on the ICC profile using the reference target as a tool described above uses only a part of the physical phenomenon in human color vision. .

A point to be noted in the color reproduction technique is that humans go through many stages to understand color as a sensation. And color reproduction technology converts colors that fully reflect these human visual characteristics,
Compression is necessary.

(1) First, light entering the eyeball is converted into an electrical signal by the cone of the retina. At this point, the mechanism relating to the automatic exposure of the human eye works, scaling to the appropriate signal strength and adjusting the sensitivity to color. (2) Next, various processes are added and perceived in the brain through the optic nerve. Among them, there are phenomena such as color averaging by a spatial filter and stereoscopic vision, such as an automatic white balance mechanism for colors and an illusion due to the influence of surrounding colors. Here, problems such as chromatic constancy and chromatic adaptability of human vision intervene. (3) In addition, the colors that humans remember from experience and the environment, for example,
There is a problem with the color memorized as a preferred color such as human skin, blue sky, and plants. Note that the above-mentioned memory colors do not match in terms of color values and color appearance, but indicate that a technique for reproducing an acceptable color is required.

As described above, the current color management system (CMS) based on the ICC profile is as follows.
It uses only a small part of physical phenomena in human color perception. The processing mechanism of human visual information is extremely complicated, and requires interdisciplinary research such as biology, psychology, and information engineering.

[0026]

SUMMARY OF THE INVENTION The present invention provides a method of producing a color print image of high quality, high image quality and matched to customer needs from a color original image (including a transparent original and a reflective original). Color reproducibility (color repr
oduction), as well as technology for producing color print images that can meet customer needs (needs for the finished tone of color print images) from any color document image, especially color document images To provide the image information processing technology.

The present inventors have established a technique for producing the above-described advanced color print image by: (i) a color original image, for example, a color transparent original (which is
The dynamic range of image density information is large and is considered to be indispensable for producing high-quality color printing, and is also called a photographic film original or a transparency original. ) Has what characteristics, and how these characteristics affect the processing of image information (?) (Ii). For color print images, R / G /
B is obtained by obtaining the image information of B and finally converting the image information into C / M / Y image information.
What is a gradation conversion method that can reasonably absorb customer needs as well as the problem of (color management)?
Also, what characteristics (performance) must the essential gradation conversion formula applied to gradation conversion have (?) (Note: In the present invention, "gradation conversion" means It should be interpreted in a broad sense to include the conversion of color tone as well as the gradation and density gradation of the original image.) (Iii).
Plates, Y plates, etc.) are produced (reproduced). However, the relationship between the halftone dot arrangement and the coloring is based on the primary color (each halftone dot of each color plate does not overlap individually). ), Secondary colors (color phenomena from areas where the halftone dots of the two color plates partially overlap), and tertiary colors (color phenomena from the three color plates). It is extremely complicated as shown in the color phenomenon from the area where the halftone dots are completely overlapped. Under such color phenomenon, color consistency satisfying the customer is realized. Investigations have been made that go back to the roots of conventional color print image production techniques, such as what kind of gradation conversion method is better for providing color print images.

In order to streamline the entire process (all processes) of producing a color print image from a color original image, the present inventors have used, in particular, color separation techniques (including color separation and gradation conversion). Items to be examined and requirements required for rationalization were identified and examined in detail (see Fig. 1).

As a result, the present inventors have applied the method of producing a color print image from a color original image in order to rationally absorb the problem of color matching (color management) and advanced customer needs. For the color separation technology (including color separation and gradation conversion), the "field" (corresponding to the subsystem of the whole system) It is extremely effective to introduce the concept (concept).

The present invention introduces an unprecedented concept of a "place" to an entire system (entire "place") for producing a color print image from a color original image, thereby realizing a complex and diverse element. Technology for producing color print images that are made up of technologies and that meet sophisticated customer needs as well as color matching (color management). In particular, color printing of halftone dots from continuous tone color original images, which is the core technology, The purpose of the present invention is to rationalize a processing method of image information applied when producing an image.

[0031]

SUMMARY OF THE INVENTION In general, the present invention provides image information of a color original image applied when producing a halftone color print image from a continuous tone color original image. In the method of processing, the method of processing the image information of the color original image includes (1) a `` place '' for organizing image information obtained from the color original image, and (2).
(3) Design a processing strategy for the sorted image information obtained in the process of (3). `` Place '' to execute the processing of the arranged image information, (4).
The process is performed through the distinctly divided and interrelated individual "places" consisting of "places" that apply the image information obtained in step (3) to the production of color duplicate images. And a method of processing image information of a color document image.

Hereinafter, the technical structure of the present invention will be described in detail. First, in order to obtain an understanding of the present invention, a color print image is produced by using a color film original (transparent original) image as the color original image, according to the present invention incorporating the concept of the above-mentioned "place". A method of processing image information of a color original when performing the operation will be briefly described. In addition,
A detailed description of each "place" will be described later.

(1) A “place” for organizing the image information of the color original image (hereinafter, also referred to as a “place” related to (1)):
The “place” related to this includes a process of setting an H portion (lightest portion) and an S portion (darkest portion) of a color film original (transparent original) image. In this step, first, in order to obtain image information for producing a production color plate (C / M / Y) of a color print image from a predetermined photographic photosensitive material that is a photographing medium of a color film original image, R complementary to the color plate
And a step of setting the density range of the color original image on the photographic characteristic curve of the / G / B photosensitive emulsion layer. Needless to say, depending on the settings of the H portion and the S portion, the H portion to the S portion where image information should be taken in on the photographic characteristic curve of each emulsion layer (R / G / B). The ultimate dynamic range will be defined.

The "field" relating to the above (1) is the influence of the photographic characteristic curve of the "photographic photosensitive material" which is the photographing medium of the color film original image. (Recognizing it).

As a method for removing the influence of the photographic characteristic curve of the photographic photosensitive material, the photographic characteristic curve itself may be converted into a mathematical expression (function). First, the photographic characteristic curve of the photographic photosensitive material is converted from the image information (vertical axis-D value) correlated with the density of the original image obtained from the color film original image and the subject forming the original image to the photographic photosensitive material. A function formula indicating a correlation with an image information value (horizontal axis-X value) correlated with the amount of incident light is defined, and then the photographic density of a photographic photosensitive material which is a photographic medium of the color film original (transmission original) image Utilizing a characteristic curve (photographic characteristic curve), based on image information correlated with the density of a color film original image, the H portion (lightest portion) to the S portion (darkest portion) of the original image excluding the characteristics of the photosensitive material are removed. , A standardized light value image which is image information correlated with the amount of light incident on the photographic photosensitive material from a subject (for example, an actual scene called an apple) which is a source of a color film original image. information( It suffices to determine the standardization light intensity value).

Further, the "field" relating to the above (1) indicates that the dynamic range of the light amount image information (standardized light amount value) is "1" from the viewpoint of efficient processing of the image information thereafter.
And the step of normalizing to

(2) A “place” for designing a processing method for the image information obtained in the step (1) (hereinafter, also referred to as a “place” in (2)): "
The R / G / B image information from the arranged color original image obtained from the “place” relating to (1) is subjected to gradation conversion to produce halftone halftone color plates (C / M / Y). It can be said that it is a place of plate making design.

The important design work of the “place” relating to the above (2) includes a work of qualitatively and quantitatively designing at least the following four items (i) to (iv). In the present invention, in order to meet the needs of advanced customers, the following (i)
The four items (1) to (iv) are characterized in that they are handled in the design work as inseparable items. Note that this point will be described later in detail. (i) H part (lightest part) and S part (darkest part) of a color print image
settings of. (ii). Setting of halftone dot values to be arranged in the H and S sections. (iii). Setting conditions for maintaining gray balance (color balance). (iv) Setting of the adjustment condition of the halftone contrast from the H section to the S section.

(3) In accordance with the processing design specifications determined in the step (2), a “place” (hereinafter referred to as “the field”) that executes the processing of the sorted image information obtained in the step (1). The “place” for (3) is the same as the “place” for (3). Each color plate (C / M /
Y) is a tone conversion (conversion of continuous tone to halftone tone, tonal conversion) in order to produce Y, which is a very important "field". It goes without saying that the “field” related to (3) includes a determination of what “gradation conversion formula” (or gradation conversion method) is to be used in gradation conversion.

The gradation conversion work in the “place” related to the above (3) is inseparable from the design items in the “place” related to the above (2), specifically, the “place” related to the above (2). i) ~
It must be performed using a gradation conversion formula that simultaneously satisfies item (iv). The present invention has a significant feature in employing the following <gradation conversion formula (1)> as the gradation conversion formula.

<Tone conversion equation (1)> y _n = y _H + [α (1−10− ^{k · xn} ) / (α−β)] · (y _S −y _H )... (1) where said at <tonal conversion formula (1)>, each symbol means the following; xn: shows the [X _n -X _H]. That is, the image information value (D) correlated with the density of an arbitrary pixel (n point) on the color original image
_n ), the image information value (X _n ) correlated with the light amount of the corresponding pixel (point n) obtained using the photographic characteristic curve, and correlated with the density of the H portion (lightest portion) on the color original image. An image information value (X _H ) correlated with the light amount of the corresponding H portion (brightest portion) obtained from the image information (D _Hn ) using the photographic characteristic curve.
Shows the basic light amount value obtained by subtracting. y _n : Halftone dot value set for a pixel on a color print image corresponding to an arbitrary pixel (n point) on a color original image. y _H : Halftone dot value preset for the H portion on the color print image corresponding to the H portion (lightest portion) on the color document image. y _s : a dot% value preset for the S portion on the color print image corresponding to the S portion (darkest portion) on the color document image. α: Surface reflectance of printing paper used for color printing. β: Numerical value determined by β = 10− ^γ . k: k = [γ / ( X S -X H)] numerical value determined by. The X _S is correlated with the light amount of the corresponding S portion (darkest portion) obtained from the image information value (D _S ) correlating with the density of the S portion (darkest portion) on the color document image using the photographic characteristic curve. The image information value (X _S ) thus obtained is shown. γ: any coefficient.

(4) A "place" for applying the image information (image information for gradation conversion) obtained in the step (3) to the production of a color duplicated image (hereinafter, the "place" relating to (4)) ): The “field” for (4) is based on the halftone generator (dots) based on the gradation conversion information obtained in the step (3).
(C / M / Y) plates used for producing and printing a color print image by a generator.

Hereinafter, the technical structure of the present invention will be described in more detail. As can be seen from the schematic description of the present invention described above,
According to the present invention, when a color print image is produced from a color original image, elemental technologies (such as acquisition of image information by a color scanner or an image setter, color separation, gradation conversion, a dosimeter, Output of halftone image by setter, production and proofreading of each color plate,
Output of a CRT monitor image for checking each color plate, printing equipment with adjusted dot gain, etc.) and the need to respond to diversified customer needs as well as color consistency. The present invention proposes a new system in which the entire system (entire “place”) is newly reconstructed and a color print image can be produced rationally.

This is because the current color print image production technology is based on the above-described color management system (CMS).
And the underlying problem is that it does not sufficiently solve the problem of color consistency seen in Japanese and does not sufficiently respond to the diversified needs of customers for the finish condition of color prints .

The present invention divides the entire "field" of the production of a color print image into several "fields" that are closely related to each other, and assigns these "fields" to a clear role or function. Take the approach. Then, in each “place”, in order to realize customer needs, an approach that positions each of a variety of complex elemental technologies in each “place” and clarifies the roles and functions that these elemental technologies must share Is adopted. The present invention relates to the above-mentioned "field", and a plurality of "fields" constituting the field.
(Hereafter, sometimes referred to as the concept of a “place” or the concept of a “place”), it is possible to rationalize sophisticated and diversified customer needs with uniformity even in a complex and diverse system for producing color print images. It is thought that we can cope.

In the whole "place" (all systems) for producing a color print image, first, in the "place" which handles the color original pixels in the first stage, the color original image itself already has high image quality, high quality, and customer needs. There are hindrance factors, complexity factors, and disturbance factors in producing a corresponding color print image.

As shown in FIG. 1, the above-mentioned high quality and high quality of the color original image, the obstructive factors, the complicated factors and the disturbance factors in producing a color print image corresponding to customer needs are, for example, the following. It is on the street. (1) Document type (reflective, transmissive, positive, negative) (2) Photosensitive material type (manufacturer brand, brand) (3) Photographic exposure (over / suitable / under) (4). Image quality (high key, low key, normal) (5). Color fog colors (red, green, blue) and their degree (6). Degree of fading (large, medium, small) (7). Color document storage conditions (8) .Other

Among the characteristics of the color original image, some types of photographic photosensitive materials (manufacturers and their brands) are shown below.
It is as follows. EK (Eastman Kodak) Ektachrome 64, Eclachrome Dupe Film 6121, Ektachrome 50 (Professional Film, Tungsten), Ektachrome 200 (Professional Film 3036), Kodachrome 2
5 (Professional, Tungsten), Ektachrome 200 (Professional Daylight), etc.
AGFACHROME-1000-R manufactured by AGFA
S, 50-RS, 200-RS, 100-RS, and the like, such as Fujichrome-50 (professional, daylight) and Fujichrome 100 (professional, daylight) manufactured by Fuji Film Co., Ltd.

A color original image having various characteristics described above, for example, a color film original (transmissive, transparen)
It should not be overemphasized that cy) must be dealt with in the first stage of producing a color print image. This is because R / G / B
The image information is obtained, and the corresponding C / M / Y image information (for producing a color plate having a complementary color relationship) is obtained, whereby each color plate (C / M
/ Y or C / M / Y / BL), that is, in view of the fact that the color original image is the origin for obtaining image information.

The color original image having the various characteristics described above is submitted to a department, a maker, or the like that produces a color print image. In such a situation, the present inventor believes that it is necessary to reconsider a `` place '' for obtaining image information from a color original image in order to make the manufacturing process of a color print image rational. thinking. The inventor has various quality,
In order to produce high quality, high quality and color print images that meet customer needs from color original images with high image quality, when obtaining image information, color film originals (transparent originals t
In the case of a ransparency image, it is necessary to obtain image information in which the influence of the photosensitive characteristics of the color film as the photographing medium has been removed (eliminated).

From the viewpoint of unifying and homogenizing image information, a color film original image of any quality and image quality, and a color film original image photographed using a color film of any manufacturer can be used. It is considered necessary to obtain image information from which the characteristics of the photographic characteristic curves of the respective color film originals have been removed at a minimum. The inventor considers that the above-described attitude of obtaining image information is an indispensable requirement for realizing color management (CM) according to the present invention.

In the present invention, as shown in FIG.
The entire system (total "place") that obtains image information from a color original image and performs image processing (color separation and gradation conversion) based on this to produce the final color print image is called "image information processing". Place. " The “place” where the above-described image information is obtained is referred to as a “place for organizing image information”. Hereinafter, the contents of the "place for organizing image information" will be described in detail.

As shown in FIG. 1, the "place" for organizing the image information of the present invention is a "place" for obtaining important image information in producing a color print image from a color film original (transparent original). About.

The “place” for organizing the image information of the present invention is
As shown in FIG. 1, (i). A color film original (transparent original) is plotted on a characteristic curve of each R / G / B photosensitive layer of a photographic material as a photographing medium (recording medium) of the color film original. A process of designating a density range (dynamic range) by an H portion (highlight portion, brightest portion) and an S portion (shadow portion, darkest portion); (ii) original image using a photographic characteristic curve of a photosensitive material (Iii) normalizing the light quantity information (value) to obtain a normalized light quantity information value.

In FIG. 1, "color separation" in the "field" means that R / G / B image information is separated into C / M / Y image information (signal value) using an R / G / B filter. Means existing information detection means, or existing color correction (color correction) means applying a masking equation or Neugebauer equation. In the present invention, the conventional information detecting means relating to the "color separation" is naturally used as it is. The existing color correction (color correction) means can be used as it is, but as will be described later, the tone conversion means of the present invention can reasonably perform not only tone conversion but also color tone conversion. For,
This eliminates the need to use the conventional color correction (color correction) technology.

Hereinafter, the "place" for organizing the image information will be described in detail.

In the production of a conventional color print image,
The image information is based on “density information value”. On the other hand, according to the present invention, for example, originals of over / normal / under exposure, originals of high key / low key, originals with various color fog, or fading (fading) are not affected by the image quality of color film originals. In order to create color print images of excellent quality without being affected by the original, etc., instead of the conventional "density values", "light intensity values" To use.

This is a point which is distinguished from the prior art. In the present invention, the reason why the "light amount value" is used instead of the "density value" of the color original image when performing the gradation conversion is as follows. Starting from various color film original images using different photographic materials of the above-mentioned various manufacturers and having different image qualities, in order to rationally convert these images, the photographs which the color film photographic materials have inherently Instead of using the “density value” that depends on the density characteristic curve, the subject (the literal base of the original image. It is necessary to use the “light amount value” from the “real scene”. Therefore, image information that does not depend on the photographic density characteristic curve (characteristics of the photographic material) of the color film photographic material must be obtained. Must.

The "light amount" is a characteristic curve of a color photographic film light-sensitive material (photosensitive emulsion) on which the original image is taken, that is, a so-called photographic density characteristic curve.
eristiccurve, photographic density (photographic des)
ity).

The photographic density characteristic curve is represented by a DX orthogonal coordinate system in which the vertical axis (D) is the density and the horizontal axis (X) is the exposure. In order to determine the "light amount", the photographic density characteristic curve of the color film photosensitive material on which the image document is photographed must be converted into a function. Then, by determining the function formula of the photographic density characteristic curve, the light amount value (X _n ) of the corresponding pixel is obtained from the density value (D _n ) of an arbitrary pixel point (n point) in the color original image. Can be. Since the photographic density characteristic curve is given as technical data from each photographic material maker, it may be converted into a function.

For example, FIG. 3 shows Ektachrome 6 manufactured by EK.
4 shows a photographic density characteristic curve of a professional film (Daylight). The method of converting the photographic density characteristic curve into a function is not particularly limited, and may be in accordance with a desired method. Needless to say, as shown in FIG. 3, the R / G / B light-sensitive emulsion layers of a color photographic film have their respective characteristic curves. , The light quantity value for the production of the corresponding color plate (C / M / Y) must be determined. Table 1 shows the results. Note that Table 1 shows a plurality of formula divisions in order to formulate the photographic density characteristic curve as accurately as possible. As the number of segments increases, a more accurate function expression of the photographic density characteristic curve can be obtained.

[0062]

[Table 1]

In the present invention, when the photographic density characteristic curve shown in FIG. 3 is converted into a function, it is represented by a scale (scale) on the D-axis indicating the density value of the color film original and log E of the subject (substantial image). D value (density value) with the same scale of the X axis indicating the light amount value
And the X value (light amount value) may be converted into a function. D mentioned above
The scaling with respect to the axis and the X axis is performed from the following viewpoints, and is considered to be quite reasonable by the present inventors. That is, it is considered to be quite reasonable in the photographic density characteristic curve. That is, in the photographic density characteristic curve, the logarithmic value of the exposure amount E (log E = logI × t) is positioned as the X-axis load, and this physical amount is evaluated by a logarithmic discrimination characteristic with respect to light and darkness of human visual perception. On the other hand, the physical quantity relating to the density on the D axis is also logarithmically evaluated in human vision. Therefore, when correlating the D axis and the X axis, it is considered that there is no unreasonableness even if the scaling is performed under the same scale. Note that the above-described scaling of the present invention is a kind of simple method, and it is needless to say that the present invention is not limited to this. For example, it goes without saying that the function may be expressed by a numerical value (actually measured value) relationship shown on the D axis and the X axis shown in FIG.

In consideration of the relative meaning of the D value and the X value, in the present invention, the physical quantity on the X axis is defined as the exposure quantity (lo).
gE = logI × t).

According to the present invention, as described above, gradation conversion is performed.
Color film original density value (D _n Value)
Rather than the subject (real image, real scene)
The image information value, that is, the light amount value (X_n The value
It is the basis. As described above, the photographic density characteristic curve
D shown in Table 1 by the functionalization of the line_nValue and X_nThe value is X =
Since it is correlated by the function formula of F (D), D
_nX from value_nThe value can be determined.

The function curves of the photographic density characteristic curves of other photographic films are shown below. (1) Table 2 shows the function formula of AGFACHROME-1000-RS. (2) Table 3 shows the function formula of FujiCHROME-50 (Professional D).

[0067]

[Table 2]

[0068]

[Table 3]

Next, the photographic density characteristic curve of a predetermined color photographic film is converted into a function, and measured data of each pixel (n points) of a predetermined color film original photographed on the color photographic film, that is, D _n Tables 4 to 6 below show the relationship between (density value) and X _n (light amount value). (1). Table 4 shows KODAK EKTACHROME-64.
Are actually measured data on a color film original. (2) Table 5 shows actual measurement data of a color film original of AGFA CHROME-100-RS. (3) Table 6 shows actual measurement data of a color film original of FUJI CHROME-100.

[0070]

[Table 4]

[0071]

[Table 5]

[0072]

[Table 6]

In the "field" for organizing the image information of the present invention, the image information of the color film original is obtained from the density value (D _n ) of the predetermined pixel (n points) as the image information of the color film original according to the above-described procedure. The light amount value (X _n ) that is not affected by the characteristics (photographic density characteristic curve) of the (photographic photosensitive material) (the characteristics are removed or “distortion” due to the characteristics is removed) is obtained. The light amount value (X _n ) is more uniform and has less distortion compared with the density value (D _n ) based on the conventional image information processing technology from the viewpoint of the qualitative characteristics of the image information. Standardized image information,
In addition, it reflects the substance of the subject (substance image) more accurately. In the present invention, the X _n value obtained from the D _n value as described above may be referred to as a standardized light value.

In the processing of the image information of the present invention, the image information of each pixel (n points) is relatively shifted in the entire dynamic range from the H part (lightest part) to the S part (darkest part) of the continuous tone image. Since the quality of image information does not change when compressed, the process includes a process of compressing the dynamic range of the standardized light amount value to “1” of 0 to 1. It is apparent from Tables 4 to 6 that the dynamic range of the _Xn value is of various sizes. The present invention
The process of compressing the dynamic range to “1” is called “normalization”. Then, the normalized (standardized) light amount value is referred to as a normalized light amount value. It should be noted that the "normalized" light amount value has a great advantage in image processing, particularly in calculation processing at the time of gradation conversion (calculation processing by the calculation software at the time of gradation conversion). It goes without saying that the details will be described later.

In the image information processing technique of producing a halftone color print image from a continuous tone color film original (transparent original) according to the present invention, it is important to follow the "place" for organizing the image information. The “place” is a “place” for examining what kind of color print image is to be produced based on the image information obtained in the above process, that is, a “place” for plate making design (plate making design). .

Image information obtained from the above-mentioned "place" for organizing image information (light amount information value instead of conventional density information value)
As shown in FIG. 1, in the plate making design for producing each color plate (C / M / Y) and black plate (BK) using the above, the following items must be examined in whole and organically. It must be.

(1). Setting of position and halftone dot value of H portion for color plate (C / M / Y) (2). Position and halftone dot portion of S portion for color plate (C / M / Y) Value setting (3). Setting for black plate (BK) (UCR amount, UCA amount, ST
(P / EDP settings) (4). Related adjustment of gradation conversion and tone conversion (color correction) when setting a tone curve (gradation conversion curve) (gradation conversion first principle) (5). Adjustment considering unnecessary components of process ink when setting tone conversion curve) (Maintaining color balance and gray balance in all ranges) (6). DOT when setting tone curve (gradation conversion curve)
・ Adjustment in consideration of GAIN (7). Adjustment of halftone contrast (8). Maintenance of gray balance and color balance (9). Reduction and enlargement magnification of finished image (10). S. The amount of M, etc.

High quality, high image, and color print images that meet advanced customer needs can be reasonably (ratinall
y) In order to manufacture efficiently and with good reproducibility, the above-mentioned items must be considered in plate making design. Although many of the various examination items described above are individually known in the art, the contents of each item will be described below in relation to the present invention.

The above (1) and (2) are used for producing color plates (C / M / Y) in order to produce an H portion (highlight portion, brightest portion) and an S portion (shadow portion, darkest portion) of each color plate. And the setting of the dot% value (the size of Dot) to be disposed here is important. The above (3) is a black plate used in combination with a color plate (C / M / Y) (an important plate used from the viewpoint of reproduction of halftone tone, black balance, control of the total amount of halftone dots, etc.). Here is an example of how to design from the viewpoint. In the present invention, it should be understood that the black plate (BK) may not always be required. UCR stands for Under
Color Romoval (under color removal), UCA is U
nder Color Addition (under color addition)
Means STP / EDP is the starting point of the black ink (Star
t point) and the end point (End point), and means, for example, from which halftone dot position to which halftone dot position of the C plate is to be inserted.

In the plate making process, setting of a gradation conversion curve (tone curve) is extremely important.
When converting a continuous tone color original image to a halftone color print image, the present invention regards tone conversion (conversion of density gradation and gradation possessed by the original) in the first place. I believe that. This is a matter of course in view of the fact that the process ink is applied on the halftone dots formed by the gradation conversion to reproduce the gradation and the color tone (the color reproduction is performed). Therefore, the present invention requires that conventional color correction (color correction) should be performed in a relative (organic) relationship with the entire area (entire dynamic range) of the color print image to be produced. Take.

In view of the above-mentioned drawbacks and limitations of a CMS (color management system) based on an ICC profile based on colorimetric values (color values), the present invention provides color correction (color) when setting a gradation conversion curve (tone curve). Correction), and the process ink (C ink =
Considering the separation of the process blue ink, M ink = process red ink, and Y ink = process yellow ink) from the ideal color (unnecessary and impure components of each process ink), how to achieve gray balance or Color balance (in other words, color / match,
It emphasizes the position of maintaining color-consistency. The emphasis is placed on making use of the contents of these studies in setting a gradation conversion curve (tone curve).

As shown in FIG. 1, when setting a gradation conversion curve (tone curve) important in the production of the color print image, other considerations include dot gain (optical and optical) at the time of printing. Physical Dot Gain), specific color (for example, skin color), specific area (halftone), etc.
Contrast adjustment, and other shades associated with it, maintaining overall gray and color balance with other areas, and the like. In relation to the above various considerations, a gradation conversion curve (tone curve) should be set objectively and quantitatively.

In the plate making design, as other considerations, as shown in FIG. 1, how to perform gradation conversion by reducing and enlarging the finished image (color print image), the sharpness of the image edge USM for issuing
The amount of (unsharp Mask) should be set.

As is apparent from the above description, the present invention provides a "place" of a design for processing image information, that is, a plate making design for producing a color print image (plate making design).
In the "place" of today, the largest color management in today's color imaging industry (CM, color matching, ie color-
The problem of consistency) can be solved by taking into account the characteristics of the halftone dots as the medium for forming the color image and the process color ink (C / M / Y ink) applied on the halftone dots. In this case, a tone conversion curve (tone curve) is set so that the gray balance and the color balance are maintained in the entire range (entire dynamic range).

The CMS (color management system) based on the ICC profile that matches the above colorimetric values (color values) is based on the colorimetric values of a color film original (IT8.7 / 1) that is a standard original (reference original). However, this is only a standardization that uses only a part of the color reproduction in human vision. On the other hand, the present invention provides a method for forming a color image (color reproduction).
Regardless of the printing ink (process ink) used as a medium, these ink characteristics are used when setting the gradation conversion curve (tone curve), and are used in the entire range (full dynamic range) of the color print image to be produced. And an objective setting of a gradation conversion curve (tone curve) so that the gray balance and the color balance are maintained.

The approach to CM (color management) of the present invention uses a medium for forming (color reproducing) a real color image (it goes without saying that it may be of any kind). On the other hand, in the entire range (the entire range from the H section to the S section) for the human vision, when the gray balance and the color balance are maintained, a color that is satisfactory for the human vision is reproduced (color ri). It is based on the concept of production. Therefore, the CM (color management) approach of the present invention can overcome the limitations of CMS due to the ICC profile.

As can be seen from the above description, according to the present invention, in setting of a gradation conversion curve (tone curve) serving as a work reference curve at the time of gradation conversion, the above-described color image formation (color reproduction) medium (printing In consideration of the characteristics of the ink and the process ink, the gray balance and the color balance are set so as to be maintained in the entire dynamic range of the color print image to be produced (the entire dynamic range from H to S). This is based on the premise that a <gradation conversion formula> is used to guarantee that this is the case. CM
(Color management) problem is overcome, high quality,
The <gradation conversion formula> employed in the present invention, which enables the production of a color print image that meets high image quality and customer needs, will be described later in detail.

Before describing in detail the <gradation conversion formula> used in the present invention, the problem of maintaining the above-mentioned gray balance and color balance will be described. (1). Maintenance of gray balance: three-color process ink (C /
When a neutral original is reproduced as neutral by (M / Y), gray balance is a very important characteristic (a primary requ
irement). (2). Maintaining color balance: three-color process ink (C /
M / Y) so that the R / G / B light reflected from all pixels (dots) of the color reproduction (print) matches the color (color) of the color original image. Should be printed. However, maintaining the color balance described above is a complicated process because the process ink has an impurity component (because it deviates from the ideal ink). Usually, the gray balance of the three-color process ink is required to maintain the color balance. And along the entire gradation range (along the entire t
In the production of a color print image using C / M / Y inks of different ratios, the color balance is printed by separating a gray scale as a neutral gray (mental gray). This is achieved by: As can be seen from the foregoing, it is extremely important in color management (CM) that gray balance and color balance are maintained over the entire range (entire dynamic range) of a color print image to be produced. The present invention employs a specific <gradation conversion formula (1)> in order to satisfy the above-mentioned requirements, and in addition to maintaining the above-mentioned gray balance and color balance, high image quality, high quality, and matching customer needs. A color print image can be produced.

The “place” of the design for processing the image information of the present invention, that is, the “place” of the plate making design of the color plate (C / M / Y) and the black plate (BK) is the specific place described above. <Tone conversion formula (1)
>, Various items to be considered in plate making design (design) are examined. Therefore, in FIG. 1, the <gray scale conversion formula> itself, which can make use of the results of the above-described various examination items, should be included in the “place” of the design for processing image information. Note that the specific <gradation conversion formula
Regarding (1)>, the theoretical derivation process and operation thereof will be described in detail in the next “place”, that is, the “place” of the execution of image information processing.

In the "field" of the design for image information processing (plate making design), as described above, various angles are used on the premise that the specific <gradation conversion formula (1)> of the present invention is used. The plate making design is made as described above. The biggest consideration in the above-mentioned "place" is CM, that is, color management (color / conformity, color consistenc).
y). In the “place” of the plate making design of the present invention, the problem of the CM (color management) is that the color management (CM) in the entire area (entire dynamic range) of the H section to the S section of the color print image to be produced is as follows. This can be overcome by setting the gradation conversion curve (tone curve) so that each pixel in the entire dynamic range can maintain the gray balance and the color balance. In this sense, the CMS (color management system) of the present invention
The method is completely different from the above-described management method based on matching of colorimetric values using an ICC profile.

Next, specific design contents for achieving CM (color management) in the “place” of the plate making design of the present invention will be described. (1) In the H and S parts of each color plate (C / M / Y), a predetermined printing ink (for example, G by Dainippon Ink and Chemicals, Inc.)
EOS-G, TK Hi-Echo manufactured by Toyo Ink Mfg. Co., Ltd.) is used to set a condition of a halftone dot value at which a gray balance (color balance) is maintained when multi-color plate making is performed. (2) At a control point of a color plate serving as a predetermined reference, for example, a predetermined control point of a C plate (for example, a part where 50% halftone dots are set, or a part of 1/4 tone of the dynamic range) The halftone dot value (for example, 50% halftone dot value) arranged there is compared with another color plate (M / Y) at the control point.
The gray scale (color balance) is maintained when the halftone dot% value is large. (3) While utilizing the conditions of (1) and (2) above, each color plate (C /
A gradation conversion curve (tone curve) is set over the entire range from the H section to the S section of (M / Y).

In the present invention, an indispensable tool for creating a gradation conversion curve (tone curve) for each color plate (C / M / Y) while utilizing the conditions (1) and (2) is the above-mentioned < It goes without saying that the gradation conversion formula (1)> is satisfied. In the present invention, in order to operate the <gradation conversion formula (1)>, in addition to the above-described conditions, the γ value must be set for the purpose. This will be described in detail in the characteristic of Expression (1)>. Preliminarily, the γ value can be determined using the above-described condition by
It can be reasonably calculated from the tone conversion formula (1)> itself. The γ value is a k value (k = γ /
[Density area of color original image] = γ / [light amount area of color original image]) and β value (β = 10 ^−γ ). It is a very important parameter in operation.

The conditions for maintaining the gray balance (color balance) under the desired printing ink (process ink) will be further described. (1). The halftone dot% values arranged in the H and S portions of each color plate (D / M / Y) are, for example, 5% in the H portion of the C plate and 95% in the S portion.
And 3% in the H section and 90% in the S section of the other M and Y versions
Should be arranged. Naturally, these conditions are changed depending on the printing ink (process ink) used.

(2) As a control point of the C plate, in the production of a color print image of halftone gradation, the pixel at the halftone dot value = 50% is determined by the tone of the image (both the grayscale and the color tone). ) Is very important in reproducing the same, it is preferable to set, as the control point, a part having a halftone dot value of 50%. In addition, the control point of the halftone dot value = 50% is from H section to S section.
This corresponds to a portion of about ４ (quarter tone) of the density of the dynamic range of the part, and is an important portion in reproducing the tone of an image in visual evaluation of a color printed image. The quarter tone region is a halftone region of the image, and in the present invention, the halftone region (region)
(M). In the present invention, it goes without saying that the portion of the management point can be set arbitrarily. At the control point (halftone) (M) of the C version,
Gray balance (color balance) is set for the M / Y plate when a halftone dot value of 50% is set for the C plate under a predetermined printing ink, for example, by setting a halftone dot value of 40%.
Can be maintained. In the M and Y plates, the gray balun (color balance) is maintained when the two dots happen to have the same halftone dot value at the control point. However, the values differ depending on the type of printing ink. For example, the M plate may be 40% and the Y plate may be 38%.

By setting the conditions (1) and (2), the γ value of the <gradation conversion formula (1)> can be obtained. For example,
For C _{plate, y n = 50 (%)} , y H = 5%, y s = 95
%, _Xn values, a light amount value (normalized light amount value) obtained from a halftone density value of a color original image using a photographic density characteristic curve, α = 1.0, β = 10 ^−γ , and k By substituting = −γ into the <tone conversion equation (1)>, the γ value can be obtained. In this case, a value of γ = 0.45 is obtained. Further, other color plates, gamma value of M / Y version, y _n = 4
Γ using values such as 0 (%), y _H = 3%, and y _s = 90%.
= 0.168 is determined.

By using the γ value for the C plate and the γ value for the M / Y plate, the gradation conversion curve (tone) for each color plate for maintaining the gray balance (color balance) over the H portion to the S portion. Curve) can be set rationally. In the present invention, one point (1/4 quarter tone, halftone) is set as the control point of the C plate. However, when the gray balance (color balance) is to be maintained at a high level over the entire dynamic range, Two or more control points may be provided. Then, in these plurality of control points, the dot% set at the control point
What is necessary is just to classify and operate the operation division of the <gradation conversion formula (1)> so as to be a value according to the number of control points.
The advantages of setting the two or more management points are as follows. In a halftone dot color print image, in a region where the halftone dot is small, the halftone dots of each color plate become a primary color coloring region that does not overlap each other. Is a color-developing area of the secondary colors which overlap each other. Further, in the area where the halftone dot is larger than the above-mentioned area, the color plates completely overlap each other.
This is because the coloring area of the next color is different, and the coloring phenomenon is different from the viewpoint. With these things in mind, the more advanced C
In order to execute M (color management), it is preferable to set a plurality of management points and perform CM.

Table 7 below summarizes the conditions for maintaining the gray balance (color balance) realized under the above-mentioned predetermined printing ink (process ink).

[0098]

[Table 7]

As shown in FIG. 1, there are various items to be examined in the “place” of the plate making design (plate making design), in addition to the items related to the CM (color management). These can also be rationally studied and determined in relation to the features and characteristics of the <gradation conversion formula (1)>.

Next, a "place" for executing the processing of the image information of the present invention will be described (see FIG. 1). First, the <gradation conversion formula> of the present invention operated in the "place" of the execution of image information processing
Regarding (1)>, the induction process and its characteristics will be particularly described.

<Tone conversion formula (1)> of the present invention is derived based on a density formula (photo density, optical density) represented by the following formula (2). D = logIo / I = log1 / T (2) where Io = incident amount, I = reflected light amount or transmitted light amount, T
= I / Io = reflectance or transmittance. Now, let the pixel area of a predetermined pixel (point n) be 1.0 (the area unit does not matter), the surface reflectance of printing paper be α, and the surface reflectance of printing ink be β, and the pixel (point n) be used. To the dot% value (y _n )
The density (D _n ) of the pixel when (for example, 5% and 10% halftone dots) are printed is obtained by the following equation (3). D = logIo / I = log { α / [α (1-y n) + β · yn]} ...... (3)

From the above equation (3), the dot% value (y_n) Is
Required by (4). y_n= [Α / α-β)] (1-10^-Dn) …………………………………………………………………………………………………………………………… (4)
A predetermined halftone dot value can be set for the shadow area.
(2) Density range and printing of original image
Since the density range of the image is different, do not compress the gradation.
(3) Along with the gradation compression,
Tone changes (including both gradation and color tone)
To reflect the practical requirements of platemaking
When the theoretical value and the measured data are transformed to match, the following equation (5)
Can be obtained. y_n= Y_H+ [Α (1-10^{-k ・ Dn}) / Α-β)] (y_s-Y_H) (5) In the above formula (5), y_H, Y_s, K means
You. (1) .y_HIs a halftone dot value preset in the H portion (for example,
When setting a 5% halftone dot in the H part of the C version, y_H= 5
You. ) (2) .y_sIs a dot% value preset in the S section (for example,
When 95% of halftone dots are set in the S part of the C version, y_s= 95 and
Become. (3) .k is k = [γ / (density area of color original image)]
Numerical value determined accordingly. The γ value for determining the k value is an arbitrary numerical value.
However, the β value is also β = 10 ^-γIs a numerical value determined by What
Note that the γ value is, for example, a solid density value (solid de
nsity), the β value is the surface of the printing ink
It will show the reflectivity. At this time, D_n= Print
Solid density value = density area of color original image
Me, kD_n= Γ.

In the above equation (5), when the basic density value obtained by subtracting the density value of the H part pixel from the density value of the predetermined pixel is used as the D _n value, and the value of α = 1.0 is used. If you, H section, a predetermined y _H value set in advance in the S portion,
The y _s value can be set. That is, in the H section,
By definition, D _n = (density value of H part−density value of H part) = 0
Since the formula (5) is y _n = y _H. Further, in the S portion, since D _n = (density value of S portion−density value of H portion) = (density range of color original image) by definition, -k ·
D _n =-gamma, and the formula (5) is y _n = y _s.

According to the present invention, as described in detail in the "field" for organizing image information, the density value (D _n ) is not used as the image information value of a predetermined pixel (n points), and the light amount value (X _n ). Therefore, if D _n → X _n is changed in the equation (5), the <gradation conversion equation (1)> of the present invention is obtained. <Tone conversion formula (1)> of the present invention employs a light quantity value (X _n ) instead of a conventional density value (D _n ) as an image information value. Is exactly the same as the above equation (5).

The output data obtained by using the <gradation conversion formula (1)> of the present invention is represented by the light amount value (xn) on the horizontal axis (X axis),
When the gray scale intensity value (y _n ) is plotted on the vertical axis, it is said that it is generally called “color separation curve” or “gradation conversion curve (tone curve)” in the art. It is not even.

Here, the difference between the prior art and the tone conversion method of the present invention will be described using the term "color separation curve". (1) Since the conventional color separation method is performed based on the density information value positioned on the density axis (D axis) of the photographic density characteristic curve as described above, the color separation depending on the D axis color separation curve is performed. It can be called a law. (2) On the other hand, since the color separation method of the present invention is based on the light amount information value positioned on the light amount value (X axis) of the photographic density characteristic curve, it depends on the X axis color separation curve. It can be said that this is a color separation method.

Next, the operation of the <gradation conversion formula (1)> of the present invention will be described. In the case of multi-color (C / M / Y) plate making, y _H and y _s are generally constant (consta
nt value). For example, in the case of the C version, y of the C version
_CH 5%, 95% y _CS, 3% to y _MH = y _YH in M and Y plate, dot percentage of 90% in y _MS = y _YS is set in advance. In the operation of the <gradation conversion formula (1)>,
(X _n ) determined in relation to the (D _n ) value measured by the densitometer
If the value of n) is used and the percentage value (% value) is used for y _H and y _s , the y value is also calculated as a percentage value.

In the operation of the <gradation conversion formula (1)> of the present invention, the γ value, which is another parameter, is an arbitrary value as described above. At the time of setting the decomposition curve (gradation conversion curve, tone curve), the γ value may be fixed to 0.45 (it can be used as a default value). According to many experiments by the present inventors, high quality and high quality color print images can be produced even when the γ value is set to 0.45.

However, the parameter γ value can change the shape of the X-axis color separation curve to the desired purpose. In other words, the desired γ value can be adjusted to achieve the desired gradation characteristics (color tone). Is a very important parameter, and is not fixed to the above-mentioned value. The numerical value setting of the parameters of the <gradation conversion formula (1)> according to the present invention is based on the situation that the tone of a given subject (substantial image) is to be faithfully reproduced on a color print image. Will be different depending on the standpoint of producing a color print image in which is adjusted (corrected or changed). In the latter case, by intentionally changing the γ value, the shape of the X-axis color separation curve can be appropriately changed to a desired one (that is, to a desired gradation). Tone color print images can be produced. For example, when the shape of the X-axis color separation curve is to be convex upward (when it is desired to emphasize the tone from the H part to the halftone), the γ value should be a positive value larger than 0 and the curve should be substantially linear. Can be set to a negative value when the γ value is close to 0, and when it is desired to make the shape concave in reverse (when it is desired to emphasize the tone of the halftone to the shadow portion).

Next, the α value (the surface reflectance of the printing paper) which is another parameter of the <gradation conversion formula (1)> will be described. Here, the β value is as described above. In the present invention, the α value may be set to 1.0. In other words, a constant may be set to α value = 1.0. This is the printing paper (substrate) used to represent color print images
Has a surface reflectance of 100%. The α value can take various values depending on the type of printing paper, but in practice, it may be set to 1.0 in order to zero-adjust the whiteness of the paper. According to the modified example (α = 1.0), y _H can be set as the brightest portion H on the print image and the darkest portion y _s can be set as expected. The conversion formula (1)> is a major feature. What has been described above is that the brightest portion H on the printed image
In, xn by definition _{= (X n -X H) =} = 0 and becomes possible, also in the darkest portion _S xn X _s -X _Hs becomes possible, namely -k · xn = -γ · (X s -X _H ) / ( _Xs-
X _H ) = − γ. As described above, by using the <gradation conversion formula (1)> (a modified example in which α = 1) of the present invention, y _H and y _s as expected are always set to the H portion on the color print image. It can be set in the S section, which is extremely important for the user to consider the work result. For example, set the value to desired to y _H and y _s in the color print image (dot% value), varying the γ value (where, alpha = 1.0), various X-axis color separation curve is obtained Can be Then, a color print image produced under these X-axis color separation curves can be easily evaluated in relation to the γ value.

It is particularly important in plate making practice that the X-axis color separation curve (gradation conversion curve, tone curve) obtained in the present invention differs from the conventional D-axis color separation curve in that the printed image as the final product is different. This is a point that the gradation characteristics and tone characteristics from H to S are displayed. Thus, plate making artisan, given y _H, through consideration of the y _s and γ values of X-axis color separation curve shape obtained under the finish of the final printed image (tone) to predict eligible to Can be. This is because when tone conversion is performed on a plurality of color original images having different image qualities (for example, different exposure conditions), the X-axis color separation curves set for each color original image are all 1
This is due to the great feature of the gradation conversion method of the present invention that the two color separation curves converge. In contrast, conventional D axis color separation curve (same y _H, employing a y _s and γ values.) Are separate D axis color separation of each corresponding to different respective color original quality image A curve is obtained and its shape is complex. Therefore, in the plate making operation, it is not possible to appropriately predict what the final color printed image will be by merely considering the D-axis color separation curve. The meaning of the above is extremely important,
On the basis of the X-axis color separation curve according to the present invention, the plate-making operator displays the X-axis color separation curve of each color plate (C, M, Y) and the black plate (B) on a monitor, for example, to display the final print image. Since the finish can be accurately predicted, various calibration operations can be made unnecessary. In other words, the present invention enables direct plate making (direct plate making method).

[0112] The the present invention in the operation of <tonal conversion formula (1)>, as k value is γ value, i.e., (X _s -X _H)
The value may be normalized to be 1.0. Normalizing such a dynamic range of X _{H to} X _S to 0 to 1 = 1.0 facilitates a comparative study between a plurality of X-axis color separation curves and a floor of a color printing image production apparatus. <Tone conversion formula (1)> by computer of tone conversion unit
(Either a software-based or a hardware-based operation method) can be extremely easily calculated. Of course, the basic light intensity value (x
n) also changes according to the above-described normalization, but does not hinder the setting of the color separation curve because it is a relative change. The normalized basal light value (xn) is
In the present invention, this is referred to as a normalized light amount value. In the following description, the calculation of y _n value is obtained by calculation using the value after normalization.

By using the <gradation conversion formula (1)> of the present invention, the multi-color plate making (generally, four plates of C, M, Y, and BK (Sumi) plates are considered as one set). In order to set the gradation conversion curve (X-axis color separation curve) for each color plate and black plate, the “field” of the design for processing the image information, that is, the color plate (C / M / Y) and black plate (BK) according to the contents determined in the “place” of the plate making design, for example, according to the condition setting for maintaining the gray balance and the color balance in the entire dynamic range, each gradation conversion curve (X
Axis color separation curve) is set.

In the "place" of the image information processing of the present invention,
The next important “place” following the “place” of the plate making design (design) is a “place” for executing image information processing. The “place” of the execution of the image information processing according to the present invention includes the determination contents of the examination items in the “place” of the plate making design (design) described above.
While utilizing the <gradation conversion formula (1)>, the light amount value (normalized light amount, xn) obtained from the image information of the continuous-tone color original image is converted to the halftone dot image information value (halftone value). point%
Value, is a "place" for the tone conversion into y _n). In the “field”, an X-axis color separation curve (gradation conversion curve, tone curve) instead of the conventional D-axis color separation curve is obtained, and each color plate (printing plate) (C / M) according to the tone curve.
/ Y) is produced.

As a method of producing each color plate (printing plate) by using the <tone conversion formula (1)>, an existing system known in the art may be used. For example, the gradation conversion unit according to the present invention may be used in a gradation conversion unit of a commercially available electronic color field device (color scanner, total scanner) or the like.
(1) It is sufficient to incorporate a mechanism that can operate (calculate)>. More specifically, a small spot light is applied to a color film original (medium image) which is a continuous tone, and the reflected light or transmitted light (image information signal) is converted into a photoelectric conversion unit (photomultiplier or CCD light receiving unit). ), Convert the light intensity into voltage intensity, and obtain the obtained image information electric signal (voltage value).
Is processed and processed by a computer, the light source light for exposure is controlled based on the processed image information electric signal (voltage value) output from the computer, and then the laser spot light is printed on raw film. A well-known existing system for creating a master plate (printing plate) may be used.

When using the existing system (for example, a color scanner), it is needless to say that the existing system must be improved so that the concept of the "place" of the present invention can be utilized. That is. Specifically, the following improvements must be made to existing systems (color scanners). (1) In the image information acquisition section (image information detection section),
Reconstruction is performed so that the light amount values (standard and normalized light amount values) described in the “field” of the image information arrangement of the present invention are obtained. (2) In the control unit (image processing control unit), the various examination items and the examination results described in the “place” of the design for processing the image information of the present invention (the “place” of the plate making design) are described. It is displayed and reconfigured so that the examination result can be instructed to the gradation conversion unit. (3) In the tone converter of the color scanner (regardless of whether it is integrated with the control unit or not), the <tone converter> described in the section of “Execution of Processing of Image Information of the Present Invention” (1) Reconfigure so that> can be operated (computed).

On the premise that the above-mentioned existing system is reconfigured, in order to carry out the present invention, a computer for organizing and processing electric signals correlated with image information of a color film original (medium image) is required. In the calculation processing mechanism section, the original image (subject) is obtained from the density information value of the color film original (medium image) recorded on the predetermined color film (recording medium) by using the color film (recording medium).
The image information value correlated with the amount of light is obtained through the photographic density characteristic curve, and the image information value is converted into image information (electric signal) for forming a halftone dot by using the <gradation conversion formula (1)>. It is only necessary to incorporate software that can do this into existing systems.

As the software described above, an information value (D _n ) correlated with the density of a color film original image is converted into an image information value (X _n ) correlated with a corresponding light amount under a predetermined photographic density characteristic curve. And <Gradation conversion formula (1)>
Owns the algorithm as software and A / D
(Analog-digital conversion), a general-purpose computer having a D / A I / F (interface), an electric circuit embodied by a general-purpose IC using the algorithm as logic, an electric circuit including a ROM holding algorithm operation results, and an algorithm. P embodied as internal logic
Various forms such as an AL, a gate array, a custom IC, and the like can be taken. Particularly in recent years, modularization has been developed, and the arithmetic processing mechanism based on the <gradation conversion formula (1)> of the present invention can be easily implemented as a dedicated IC, LSI, microprocessor, microcomputer, or other module. Can be manufactured.

Then, the spot lights for photoelectric scanning are sequentially emitted.
If the laser beam is exposed while being divided into points, and the laser exposure unit is also synchronized with the point, the <gradation conversion formula (1)>
The numerical value of the dot area percentage (y
The printing original plate (printing plate) having the halftone gradation having _n ) can be easily prepared and printed.

As described above, the method of processing image information of a color original image, which is a core technical means applied to the production of a color print image of the present invention, is a concept of a “place” not seen in the prior art. To clarify the division of roles of the functions of each "place", thereby producing color print images rationally and efficiently, which is the biggest problem in the production of color print images Color-consiste
ncy) and the like (color management). FIG.
Are shown together.

[0121]

Next, the present invention will be described in more detail with reference to examples. In the following embodiment, in duplication of a color print image, gray balance (color balance) is maintained over the entire dynamic range, which is the center of the tone conversion work of the image, and tone (color management) that is easy to perform in CM is easy. An example of setting a conversion curve (tone curve, color separation curve) will be mainly described.

(Example 1) (1) Regarding a color film original image and a photographic density characteristic curve of the color film: As a color film original image (transparent original), a photosensitive material film manufactured by Company F (Fuji Corporation, FUJI. (CHROME) was used. The reasons for selecting the above three types of color film original images are as follows. The image quality of a color film original image (medium image) varies depending on the exposure conditions at the time of photographing, such as a standard image (appropriate exposure) and a non-standard image (over / under exposure).
In order to verify whether the present invention can reasonably cope with these variously different color film originals, a color film original having a different density range (Density Range = DR) (D-axis density range) Are different). (a). Density range (dynamic range) D =
0.18 to 2.70 (bright original, overexposure) (b). Density range (dynamic range) of original image D =
0.30 to 2.80 (normal original, exposure correction) (c). Density range (dynamic range) D =
0.60-3.10 (dark original, underexposure)

FIG. 4 shows a photographic density characteristic curve of the photosensitive material film manufactured by Company F. Further, a function formula showing a correlation between the D value (density value) and the X value (light amount value) of the photographic density characteristic curve is shown in Table 8 below.

[0124]

[Table 8]

(2) Regarding the setting conditions of the gradation conversion curve (tone curve, X-axis color separation curve) of the present invention: using the photographic density characteristic curve of FIG. And D on the D axis of various color film original images
_{The n} value is converted to an _Xn value on the X axis to obtain a light amount value (standard value), and this is normalized to obtain a normalized light amount value (xn).
Ask for. Next, the xn value was converted into a dot area% value (y _n value) by <gradation conversion formula (1)>.

The operation conditions of the <gradation conversion formula (1)> are as follows. (i) Under the printing ink (process ink) used,
<Gray balance (color balance) maintenance condition> in Table 7 was adopted as the condition for maintaining the gray balance (color balance) at the control point (the part where the 50% halftone dot of the C plate is set). (ii). Other operating conditions are as follows. . The γ value of each color plate to satisfy the <gray balance (color balance) maintenance condition> in Table 7 is γ (C) =
0.45 and γ (M / Y) = 0.168. In this embodiment, in addition to the color plate (C / M / Y), a black plate (BK) was also created. This black plate (BK) is the dot 5 of the C plate.
It was set so that 0% of the region was defined as the starting point (STP) and 95% of the C-plated region was defined as the end point (EDP). The γ value for the black plate (BK) was set to γ (BK) = − 0.50. . The α value was set to 1.0.

(3) Regarding the data for setting the gradation conversion curve (tone curve, X-axis color separation curve) of the present invention: Tone conversion was performed on three types of color film original images to obtain tone conversion curve setting data. The results are shown in Tables 9 and 1 below.
0, shown in Table 11.

[0128] In Table 9 to Table 11 below, the tone intensity value (y _n) is shown as a color plates dot% value of (C / M / Y) and black plate (BK). Further, in the table, the normalized light intensity value (xn) is to standardize light value dynamic range _{(DR) (X s -X H} ) of (xn) was determined by normalizing to 1.0. When the standardized light value (X _n ) is converted to a normalized light value (xn),
In the operation of (1)>, k = γ / (X _Sn −X _Hn ) = 1 /
1 = 1, and the calculation load is greatly reduced. In addition,
Even _if the DR of the standardized light amount value (X _n ) is adjusted to 1.0, the gradation intensity value (y) set at each pixel point (n point) is also relativized and changes. It does not adversely affect the image quality. The standardized light value ( _Xn )
In order to obtain the normalized light quantity value (xn) from the following equation, the following equation may be used. ( _Xn ) = ( _{Xn− XHn} ) × [(DR adjustment range) /
(X _Sn −X _Hn )] In the case of Table 9 below, the formula for calculating the normalized light value (xn) from the standardized light value (X _n ) is as follows. ( _Xn ) = ( _Xn− 1.02) × [1 / (2.85-1.02)] = ( _Xn− 1.02) × (1 / 1.83)

[0129]

[Table 9]

[0130]

[Table 10]

[0131]

[Table 11]

[0132] In the present invention, the table is normalized light intensity value indicated in 9 Table 11 (xn) dot percentage data (y _n) is to be seen if graphed, the color film original image Whatever the image quality (in the above case,
Exposure over / normal / under. ), The surprising fact that the gradation conversion curves (tone curve, X-axis color separation curve) fit into one thing. On the other hand, a conventional D-axis color separation curve (a curve showing the relationship between the density value and the dot% value in Tables 9 to 11)
Can be understood as curves corresponding to each other and a complicated curve. The usefulness of the facts described above in plate making is important in plate making, and the person making plate making needs to know how the color printed image as the final product to be made by the gradation conversion curve (X-axis color separation curve) of the present invention. It is possible to consider in advance whether the tone has a proper tone (gradation and color tone).
However, the above cannot be performed under the conventional D-axis color separation curve.

In the plate making operation using the <gradation conversion formula (1)> of the present invention, it is possible to produce a high quality and high quality color print image in which the gray balance and the color balance are maintained by the entire dynamic range. it can. That is, the inventor of the present invention has developed a 455 manufactured by ISOMET of the United States, which is known in the art as a high-end (meaning that high-quality printed images are produced) and low-end color scanners.
And 405 DIGITAL COLOR SCANNER
In addition, plate making was performed by incorporating the concept of the "place" of the present invention.

More specifically, in the color scanner, software for obtaining a light amount value (X _n ) from a density value (D _n ) is incorporated in a density detection unit, and a control of an image processing control unit (control unit) is performed. In addition to allowing the panel to issue a command for the contents of the plate making design (design), software for operating the <tone conversion formula (1)> in the tone conversion unit operating under the command is incorporated, and the printing plate (C /
(M / Y / BK), and the effect of the present invention was confirmed by composing the printing plate. As a result, it has been found that, according to the present invention, a high-quality, high-quality color print image that matches customer needs is produced regardless of the image quality of the color original image. Further, the produced color print image has excellent gray balance / color balance over the entire dynamic range.
(Color management) was found to be an important tool.

In the plate making operation described above, (1) the density detecting section is responsible for sharing the function of the "place" for organizing the image information of the present invention, and (2) the image processing control section (control section).
Performs the function sharing of the “place” of the plate making design (design) of the present invention, and (3) the gradation conversion unit performs the function of the “place” of executing the processing of the image information of the present invention. It goes without saying that sharing is done.

(Embodiment 2) In the present invention, a "place" of design for processing image information, that is, a color plate (C / M / Y)
It is important to maintain various objective data in plate making design (design) for plate making and design of black plate (BK) in order to enhance the performance of the place. It is. For example, it is important that the “place” holds objective data for adjusting and managing the finished tone of a color print image as a final product.

According to the present invention, the <gradation conversion formula (1)> is used as an important tool, and in view of the characteristics of the <gradation conversion formula (1)>, the objective adjustment / management data described above is used as the tool. It can be obtained from <gradation conversion formula (1)>. Table 12 below shows data for adjusting and managing the finished tone of a color print image created by using the <tone conversion formula (1)>. Based on the adjustment and management data described above,
The “place” of plate making design (design) is a color plate (C / M / Y)
Of the halftone dot value to be set in the H and S sections of the section (H section to
(Stone dot range), gradation conversion curve (tone curve)
(Largely depending on the γ value), a black plate (BK) tone curve, and the like can be objectively and rationally determined.

The notes in Table 12 below are as follows. (1) Table 12 is a data list for setting a C plane which is a color printing reference curve of the gradation conversion curve. (2). The dot (area)% value in the table is calculated by using <gradation conversion formula (1)>, and the obtained numerical value is rounded off to one decimal place. (3).
Value "and (1-10- ^γ ) value. (4) When a halftone dot value other than 5% is used for the H portion of the C plate, it is necessary to consider conditions for maintaining gray balance (color balance). This table is 50% for C version
The part where the halftone dot is set is a control point for maintaining the gray balance (color balance). (5) In the table, “γ value” is −0.3500 to 0.55,
Data in which the “% area” is in the vicinity of (5 to 80) to (5 to 60) is reference data when creating a black plate (BK).

[0139]

[Table 12]

[0140]

The present invention relates to a method for processing image information of a color original image which is a core technical element in a process of producing a halftone color print image from a continuous tone color original image. It is. In particular, the present invention has been made in view of the drawbacks of the conventional method of processing image information in producing a color print image, for example, the fact that its biggest problem, color management (CM), has not been sufficiently solved. , The color management (CM)
In addition to the above-mentioned solution, it is intended to enhance the processing technology of the color original image image information at the time of producing a conventional color print image.

According to the present invention, as a method of processing image information of a color original image applied to the production of a color print image, all systems (entire “places”) related to the processing of image information are clearly assigned functions and roles. A method in which image information is processed in each of the different “places” that are divided into several different “places”
In other words, the concept of a “place” is introduced to process the image information of the color original image rationally and efficiently.

The method for processing image information of a color original image according to the present invention eliminates opacity and ambiguity in image information processing in the entire process of producing a color print image. Therefore, the present invention can convert the color separation technology located at the beginning of the image information processing system (entire “field”) into a rational and regular system element technology, and furthermore, the system software for image information processing can be converted. Can be streamlined.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the complexity of a color separation technique.

FIG. 2 is a workflow diagram of image information processing according to the present invention.

FIG. 3 is a diagram showing a photographic density characteristic curve of a color film manufactured by EK.

FIG. 4 is a view showing a photographic density characteristic curve of a color film manufactured by Company F.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junichi Naya 5-9-7 Toranomon, Minato-ku, Tokyo Yamatoya Corporation F-term (reference) 2H084 AA30 AE01 AE05 AE06 BB04 CC18 5B050 AA09 BA15 CA08 DA04 FA02 FA03 FA05 GA04 5C077 MP02 MP08 NN02 NN03 NP01 PP15 PP32 PP33 PP37 PP38 SS07 TT02 5C079 HB03 LA11 LA12 LA23 LB02 LC12 NA03 PA02 PA03 PA08

Claims (9)

[Claims] 1. A method for processing image information of a color original image applied when producing a halftone color print image from a continuous tone color original image, wherein the image information of the color original image is processed. (1) A `` place '' for organizing the image information obtained from the color original image, (2) A `` designing a processing method for the organized image information obtained in the step (1) '' (3). According to the design specification of the processing policy determined in the step (2), the processing of the arranged image information obtained in the step (1) is performed. This is performed through the distinctly divided and interrelated individual `` places '' consisting of `` places '' which apply the image information obtained in the step (3) to the production of color reproduction images. Image information of a color original image when producing a color print image Law. 2. A method according to claim 1, wherein the color original image is a color film original (transparent original) image photographed on a predetermined photographic material (photosensitive material). . 3. The "place" for organizing the image information of the color original image in the step (1) is a color film original (transparent original).
3. The method for processing image information of a color original image according to claim 1, further comprising a step of setting an H portion (lightest portion) and an S portion (darkest portion) of the image. 4. The "place" for organizing the image information of the color original image in the step (1) is a color film original (transparent original).
Utilizing a photographic density characteristic curve (photographic characteristic curve) of a photographic material as a photographing medium of an image, an H portion of an original image in which characteristics of the photographic material are excluded from image information correlated with the density of a color film original image Standardized image information of all pixels from the (lightest part) to the S part (darkest part), which is correlated with the amount of light incident on the photographic material from the subject forming the original of the color film original image 3. The method for processing image information of a color original image according to claim 1, further comprising a step of obtaining the obtained light amount value image information (standardized light amount value). 5. A method according to claim 1, wherein a photographic density characteristic curve (photographic characteristic curve) of the photographic material is based on image information (vertical axis-D value) correlated with the density of the original image obtained from the color film original image. 5. A method for processing image information of a color document image according to claim 4, wherein the characteristic curve indicates a correlation with an image information value (horizontal axis-X value) correlated with the amount of light incident on the photographic material from the subject forming the image. . 6. The dynamic range of a standardized light amount value is 1
5. The method for processing image information of a color original image according to claim 4, wherein the normalized light amount value image information (normalized light amount value) is obtained by normalizing the image information. 7. A "place" (a "place" in plate making design) for designing a processing method of image information in the process (2) includes: (i) an H portion (lightest portion) and an S portion of a color print image; (Darkest part)
(Ii). Setting of halftone dot values to be arranged in H and S sections; (iii) Setting of gray balance (color balance) maintenance conditions; (iv). From H section to S section 3. The method for processing image information of a color document image according to claim 1, further comprising the step of at least setting halftone contrast adjustment conditions. 8. A "place" for executing the processing of the image information in the step (3) includes: (i) an H portion (lightest portion) and an S portion (darkest portion) of a color print image;
(Ii). Setting of halftone dot values to be arranged in H and S sections; (iii) Setting of gray balance (color balance) maintenance conditions; (iv). From H section to S section 3. The method according to claim 1, further comprising a step of executing image information processing by employing the following <gradation conversion formula (1)> capable of operating the setting specification of the halftone contrast adjustment condition. A method for processing the image information of the described color original image. <Tonal conversion formula _{(1)> y n = y} H + [α (1-10 -k · xn) / (α-β)] · (y S -y H) .................. (1) However, in the above <tonal conversion formula (1)>, each symbol means the following; xn: shows the [X _n -X _H]. That is, the image information value (D) correlated with the density of an arbitrary pixel (n point) on the color original image
_n ), the image information value (X _n ) correlated with the light amount of the corresponding pixel (point n) obtained using the photographic characteristic curve, and correlated with the density of the H portion (lightest portion) on the color original image. An image information value (X _H ) correlated with the light amount of the corresponding H portion (brightest portion) obtained from the image information (D _Hn ) using the photographic characteristic curve.
Shows the basic light amount value obtained by subtracting. y _n : Halftone dot value set for a pixel on a color print image corresponding to an arbitrary pixel (n point) on a color original image. y _H : Halftone dot value preset for the H portion on the color print image corresponding to the H portion (lightest portion) on the color document image. y _s : a dot% value preset for the S portion on the color print image corresponding to the S portion (darkest portion) on the color document image. α: Surface reflectance of printing paper used for color printing. β: Numerical value determined by β = 10− ^γ . k: k = [γ / ( X S -X H)] numerical value determined by. The X _S is correlated with the light amount of the corresponding S portion (darkest portion) obtained from the image information value (D _S ) correlating with the density of the S portion (darkest portion) on the color document image using the photographic characteristic curve. The image information value (X _S ) thus obtained is shown. γ: any coefficient. 9. A "place" to which the image information of the step (4) is applied.
Is at least halftone C obtained from the step (3).
(Cyan) version, M (Magenta) version, and Y (Yellow)
3. The method for processing image information of a color original image according to claim 1, wherein a color print image is produced using a color plate of the plate.