KR0164030B1 - Color scanner - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide a color scanner incorporating a new color separation technique incorporating (fusion) of gradation adjustment and hue adjustment, although difficult in the prior art in producing a color print image.

The configuration of the present invention for this purpose is that (1) the characteristic curve of the recording medium (X value) incident on the recording medium and the density value (D) formed on the recording medium. Value) using the characteristic curve defined in the DX rectangular coordinate system] to obtain the light quantity value (X value) from the density value (D value), and (2) the light quantity value (X value) using the following gray scale conversion equation. To obtain the halftone value (Y value) by performing gradation conversion, and (3) the hue adjustment step used in the gradation conversion, wherein the hue adjustment step includes (3-1) H part (most part) of the color original image. A color tone management point M ₁ for managing the color tone of the color print image is set at a desired portion between the S portions (the darkest portions), and (3-2) in the color tone management point M ₁ , (3-3) The color tone tube described above is defined by the dot value of the desired color plate (C plate, M plate, Y plate, and BL plate). Point (M ₁₎ to the value halftone dot% of the desired to be set to light intensity levels and saekpan halftone dot% value, and the H section and the S section of reflecting the adjustment condition of the tones assigned to the gray-scale conversion equation to determine the value γ and the saekpan in A gradation conversion equation is provided for gradation conversion of the light quantity value of the pixel from the H portion to the S portion of the pixel to the halftone value, and (3-4) each pixel for each color plate is prepared using the gradation conversion formula for the color plate in which the γ value is determined. The color tone is controlled and adjusted in addition to the tone conversion. The color scanner is characterized by adjusting the color tone.

Gradation Conversion

yn = y _H + [k (1-10 ^-kx ) (ys-y _H ) / (k-β)]

Description

Color scanner

1 is a diagram showing a density characteristic curve (manufactured by F Company) of a color film.

2 is a block diagram of a color scanner according to the first embodiment of the present invention.

3 is a diagram illustrating a color separation curve used as an outline of the basic experiment of the present invention.

4 is a block diagram of a color scanner according to a second embodiment of the present invention.

5 is a block diagram of a color scanner according to a third embodiment of the present invention.

6 is a block diagram of a color scanner according to a fourth embodiment of the present invention.

7 is a block diagram of a color scanner according to a fifth embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1 detection unit 2 color separation unit

3: Gradation adjustment part 4: Output part

5: Color Original Image 11: Gradation Converter

[Industrial use]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a plate making scanner (hereinafter referred to as a color scanner) for producing a printing plate for producing a color print image by performing gradation conversion of image information obtained by photoscanning a color original image of continuous gradation.

In particular, the present invention relates to a color scanner having a new function in the gradation conversion unit, which is a core requirement of the color scanner.

In detail, the gradation converting unit of the color scanner according to the present invention does not use the conventional density information value as the image information of the color original image, but rather the characteristic curve of the recording medium on which the color original image is recorded (the amount of light incident on the recording medium and the recording). In order to exclude the influence of the characteristic curve defined by the density value formed on the medium, a function of adjusting the color tone when integrating the light amount value of the color original image using a specific tone conversion formula is incorporated. There is a characteristic in point.

Since the gradation (also referred to as density gradation or gradation) of the color scanner of the present invention can quantitatively control hue and hue quantitatively, a high value-added color scanner incorporating the adjustment of gradation and hue according to the present invention Is provided.

The present invention relates to a color scanner incorporating a new gradation conversion technique incorporating gradation and color tone control as described above. However, the following description of the present invention is given with the emphasis on the rationalization and quantification of the tonal adjustment method of the prior art, in particular, in that the tone converter of the color scanner is constituted by having a new color tone management adjustment function.

[Private Technology]

As is well known, various color reproduction images, such as print images, copy images, printer output images, and TV (video) images, are made from original images recorded on various recording media by various color reproduction techniques. It is produced.

In the production of these color reproduction images, first, the density gradation (gradation) and color tone (color, toe) of the color original image are reproduced on the color reproduction image by Hi-Fi color (high fidelity color). Secondly, adjusting to having a desired state (including both gradation and hue) is an extremely important task.

However, in the prior art, it is a reality that the above-mentioned problems are not reasonably performed with work regularity.

This is based on the technique of faithfully reproducing the state (gradation and hue) of the color original image described above, and adjusting (modifying or changing) the state of the color original image to a desired state. Reasonable theory for nonlinear conversion processing technology (hereinafter referred to as image conversion technology or image conversion method) for converting image information of a color original image to be converted into image information, particularly in a density region, to half-tone gradation This is because the grayscale conversion of images is unscientifically and unreasonably dependent on human experience and feelings.

Hereinafter, the field of the production technology of color print images in which the present invention is directly related to the above point and always high quality is required will be described.

In the prior art, when producing a color print image which is a duplicate image from a color film document (about 90% of the color film document is of a transmissive or transmissive type), from the brightest part (H part) to the darkest part (S part) of the color film. The color separation curve (color resolution characteristic curve, dot gradation characteristic curve), which determines the correlation between color film original images of continuous gradation and color print image of halftone gradation, which are duplicate images, without having an idea of reasonably grasping density characteristics. It is said that the setting of 」is completely dependent on human experience and feeling.

In general, color printed images are color-separated from color film original images (hereinafter referred to as color original images) by a color scanner, and multicolor plates (generally C, M, Y, Four plates of the BL plate are made into one set) to reproduce the color print image of halftone gradation.

As is well known, the C plate (cyan), M plate (magenta), and Y plate (yellow) are complementary colors in the dark blue color corresponding to R (red), G (green), and B (blue) of the additive color method. As a relation, BL plate is called black or black plate.

The color scanner described above is a mechatronics extremely expensive device, but one of the major problems in the art is that its operation rate is at an extremely low level of about 30% on average. The main reason why expensive color scanners and the like have such low operation rates is that the scanner setup time for operating the color scanner is long, and that the quality of the product obtained by the color separation operation is unstable and inadequate and rescanned. (rescan, remake) are many.

Considering this from a technical point of view, as described above, an apparently expensive mechatronicized color scanner or the like is used as a color separation tool, but a plurality of element technologies of color separation operations, for example, color reproduction, color correction, The technique of color reproduction and color correction and the conversion technique of gradation are not coherently organized, and it can be said that this is the main cause of the low cost rate of color scanner.

As is well known, among the two element technologies described above, the techniques such as color reproduction have been pursued scientifically by applying the Masking equation or the Neugebauer equation.

However, this technique is left unattended as a reasoning theory cannot be supported for the conversion technique of the density gray scale of the latter image (this results in the problem of what size dot dot should be set for all the pixels in the color original image). The state depends heavily on human experience and feelings.

Since various devices for color separation have been developed under such a state, in view of the practice of color separation under the unified adjustment of color tone and gradation, the basic design technology is inexperienced in the device itself, and it is expensive and expensive in practical work. While using an electronic color separator (color scanner), the operator's guess work and the operator's experience and feeling cannot be excluded (Without operatorevalution, Without operator's guess work), and it is difficult to always produce stable, high quality color print images. Situation.

In particular, if a color document image is not a standard document produced under appropriate shooting and exposure conditions, and appropriate development conditions, for example, an overexposed document due to overexposure, an overexposed document due to underexposure, a high-key or low-key original, In the case of non-standard manuscripts such as color cast originals or faded originals, color separation cannot be performed reasonably and efficiently. In other words, it is not possible to reasonably perform color separation on these non-standard color original images, and there are problems such as low price ratio of color scanner, instability of product quality, and increase of rescan ratio.

[Problems to Solve Invention]

The inventors of the present invention faithfully reproduce the image quality of the color original image (the quality of which is gradual by both gradation and hue), and furthermore, the desired state (gradation and hue) from the above-described various color original images. In order to reasonably produce a color reproduction image of a half tone gray scale with a color conversion image, prior to the improvement of the color reproduction and color correction (correction) technique, the conversion technique of the density gradation of each pixel of the color original image is not reasonable. I have a basic perception of no.

Under the basic recognition of the present inventors as described above, the present inventors have previously proposed a method of rationally converting the gradation of a color original image under a new gradation conversion formula to obtain a certain result. (For example, Japanese Patent Application No. 63-114599) US Pat. No. 4,924,323: Heiwon 1-135825, USP5,313,310: Heiwon 1-212118, USP5,057,931: Heiwon 3-78668, USP5,134,494.

The novel gradation conversion method proposed by the present inventor has a deep relationship with the present invention, but only the outline of the gradation conversion method will be described here and the improvement thereof will be described. Needless to say, the above improvement point becomes an essential technical configuration requirement of the present invention.

In the prior art, the color separation of a color original image is a photosensitive material (photosensitive emulsion) from a literal original image (a subject, an actual image, or an actual scene, for example, if the subject is an apple, the apple body). ) Is a color photographic image obtained by recording a projectile incident on a "recording medium" under predetermined exposure conditions (as described above, when the incident light intensity I and incident time t are conditions of exposure E). On the basis of the density information, a color separation operation (a color separation operation includes both reproduction of gradation and reproduction of hue as described above).

As is well known, a photographic density is formed on a photosensitive material on which a subject such as a still life or a person is photographed, thereby forming a media image. The curve indicating the correlation between the photographic concentration (blackening degree) and the exposure amount E of the photosensitive photosensitive material is a photographic density characteristic curve. This is displayed by taking the photographic concentration D (D = log Io / I) on the vertical axis and the logarithm of the exposure amount E on the horizontal axis. It goes without saying that the ratio between the intensity I of the transmitted light and the intensity Io of the incident light is used for the film or the plate (transmission document), and the ratio between the intensity I of the reflected light and the intensity Io of the totally reflected light is used for the photo paper (reflected document). .

The photographic concentration characteristic curve (hereinafter simply referred to as concentration characteristic curve) is typically a complex curve having a curved leg portion below, a nearly straight straight portion (straight middle portion), and a curved shoulder portion above. Refer to FIG. 1 to be described later).

Incidentally, in the prior art, the color separation operation is performed based on the density information value of each pixel of the color original image.

In other words, the color separation technique of the prior art is assembled from the position of the longitudinal axis (concentration value) of the concentration characteristic curve. The image information value (density information value) of the color original image (medium image) on which the prior art is based on the color separation operation is not proportional to the image information value of the original image (real image, subject, real image), It was greatly influenced by the photosensitive characteristics (concentration characteristic curve) of the photosensitive photosensitive material (photosensitive emulsion). That is, the photographic density of the color original image as the media image does not correlate in a linear relationship (45: 1 linear relationship with 1: 1) to the exposure amount (large value) which is the image information value from the subject (solid image, real diameter).

Moreover, it is well known that the discrimination characteristic of the contrast in human vision is algebraic, and the human being evaluates its contrast based on the discrimination characteristic described above based on the amount of light incident on the visual system from the subject (real image). Here, it is felt that the gradient of the change in concentration is linear.

As can be seen clearly from the above, in the production of a color print image, the color separation of the medium image recorded in the photosensitive material (D = log I _O / I) is carried out with a clue to the color of the photosensitive material. It is assumed that the density information value after being influenced by the photosensitivity characteristic is used, and the image information value (light quantity value) obtained from the subject (solid image, real diameter) which is the true object of duplication is not used.

In view of the above situation, the inventors of the present invention have described an image information value of a medium image which has been changed non-linearly by the photosensitive characteristic (concentration characteristic curve) of a recording medium (photosensitive material) as an image information value when producing a color print image. Rather than an approach using density values, a careful examination is made of a method of producing a printed image based on image information values related to the amount of light such as the first (live, primitive) exposure amount obtained from a subject (real image, real diameter). Was added.

As a result, in the conversion operation of density grayscale, which is primarily important in color separation, (1) the vertical axis (D = log Io / I) of the density characteristic curve (photo concentration characteristic curve) of the photosensitive material on which the color original image is recorded and recorded. The value of the horizontal axis (log E) is obtained from the density value of (), hereinafter, the vertical axis is also called the D axis and the horizontal axis is called the X axis. In other words, the light quantity value on the X axis is obtained from the density value on the D axis of the color original image (medium image). More specifically, (2) the density information D _{n on} the D axis of the pixel point (n point) of the mouth of the color original image is projected on the X axis through the density characteristic curve, and is related to the exposure amount of the corresponding pixel. The image information value X _n is obtained, and then (3) on the basis of the X _n value (light quantity value) obtained as described above, and the gradation conversion _formula proposed by the present inventors and the like (this is employed in the present invention described later). It's exactly the same as the gradation formula, but Brightness is completely different in terms of use and application of the gradation conversion formula.) When a gradation conversion of an image is performed on the basis of the gradation conversion formula, a color print image having excellent image quality with faithful image characteristics to a subject (real image and real image) is produced. Found.

The gradation conversion technique proposed by the present inventors is applied for the gradation change which is most important for producing a color printed image of half tone as is apparent from the above.

That is, the gradation conversion technique proposed by the present inventors is used to produce a duplicate image of a natural gradation of color in human vision, with a density of 1: 1 fidelity of various manuscript images including a color original image. Will be.

In addition, the above-described manufacturing conversion technique is not only a color original image, but also a non-standard document (exposure over or under exposure, high key or low key, color blurring or fading, etc.). This is useful for reproducing concentration gradations that are considered to have.

In addition, it was confirmed that in the above-described gradation conversion technology, the hue (color tone) under the faithful reproduction of density gradation is also reproduced with rich contents.

However, as described above, the gradation conversion technique proposed by the present inventors emphasizes the conversion of the system in color separation, namely, the Hi-Fi conversion of the gradation gradation (between the original image of the continuous gradation and the duplicate image of the halftone gradation). (Converts to 1: 1 high fidelity) and realizes high fidelity and reasonably gradation conversion by the gradation conversion technique, and abundant hue reproduction with the gradation conversion. It became.

Therefore, the market demand for the quality of color print images has become more and more complicated, diversified, and not just a requirement of the reproduction of color print images with the state of the color original image (gradation and hue).

For example, if you want to emphasize the color of a specific part (portrait, ceramics, clothing, furniture, woodwork, painting, etc.) or a specific part (area) of a color manuscript, There is a request to change the desired ones such as dark green tone, light green tone, pink tone, and sepia tone.

In the case of responding to such a demand, for example, even if it is reproduced by requesting a specific color tone in response to the conventional color correction technique, the state of the whole image is distorted and the deterioration of the image quality is severe and the above requirement is satisfied. We are faced with the problem of being unable to answer. Needless to say, it is important to establish a gradation and hue conversion technique that gives a natural sense to both the hue of a particular portion or a specific area (region) and the entire state of the image.

In order to cope with the advancement and complexity of the above market demand, it means that the color separation technology requires the unification (convergence) of the gradation conversion technology and the color tone adjustment technology.

In that case, it should be noted that the halftone dots forming the color print image always have a direct relationship with both gradation and color tone or both density and color. This is obvious from the fact that the image quality is determined by the size of the dot (defining the density gradation) and the coloring ink (defining the color) applied to the dot.

In addition, the present inventors have established a means for reasonably adjusting and managing the size of the halftone in the grayscale conversion technique proposed above. Therefore, the present inventors made a careful examination under the recognition that the integration of the gradation adjustment technique and the hue adjustment technique described above is an extension of the gradation conversion technique proposed by the present inventors. As a result, when the present inventors adopted the gradation conversion formula, which is the core of the gradation conversion technology proposed above, and fuse the idea of hue adjustment here, the present inventors can reasonably adjust and manage both hue and gradation in color separation work. Realized.

The present invention has been completed on the basis of the above facts, and according to the present invention, it is possible to adjust the color tone to reasonably adjust and manage both the color tone and the gray scale, and to adjust the color tone as desired in the reproducibility of the rich gray scale, which was difficult in the prior art. It is to provide a color scanner incorporating a management control technique of color tones. In addition, the color scanner of the present invention has a great feature in that it is equipped with a color separation technology in which both gray and hue are integrated as described above.

However, in the following description of the color scanner of the present invention, in view of the reality that the prior art cannot reasonably and quantitatively manage color tone, in particular, the emphasis is on the function of adjusting and adjusting the color tone of the tone converter, which is a core component of the color scanner. This is explained with reference to.

Means to solve the problem

According to the present invention, the gradation conversion unit in a color scanner for producing a printing plate for producing a color print image of halftone gradation by gradation conversion of image information of a color gradation image of a continuous gradation in a gradation conversion unit of a color scanner. 1) Characteristic curve of recording medium recording color original image [Characteristic curve defining the relationship between the light quantity value (X value) incident on the recording medium and the density value (D value) formed on the recording medium in a DX rectangular coordinate system] 2) A function for obtaining the light quantity value (X value) from the density value (D value) by using 2) the gradation conversion of the light quantity value (X value) using the following gradation conversion formula and obtaining the halftone value (y value), and 3 The color tone adjustment function used in the gradation conversion is 3-1) to manage the color tone of the color print image at a desired area between the H (most part) and the S (the darkest part) of the color document image. Color management point (M ₁ ) 3-2) In the color tone management point M ₁ , the condition for adjusting the color tone is defined as the percentage of _half point of the desired color plate (C plate M plate Y plate and BL plate), and 3-3) the color tone management The gamma value is determined by substituting the halftone value of the color plate reflecting the light quantity value at the point M ₁ and the adjustment condition of the color tone, and the desired halftone value set in the H and S portions in the following gray scale conversion equation. Gradation conversion equations are provided for gradation conversion of the light quantity values of pixels ranging from the H portion to the S portion of the color plate to the halftone value, and 3-4) each of the color plates using the gradation conversion equation for each color plate in which the? A color scanner is characterized in that it is configured as a color tone adjusting function which consists of a configuration of adjusting and adjusting the color tone with gray scale conversion of a light quantity value of a pixel.

Gradation Conversion

y _n = y _H + [α (1-10 ^-kx ) (y _s -y _H ) / (α-β)]

The meanings of the symbols in the gray scale conversion equation are as follows.

X: represents (X _n -X _H ), that is, the light quantity value X corresponding to the density information value D _n of an arbitrary pixel point (n point) of the color original image obtained using the characteristic curve of the recording medium. _n ) represents the basic light quantity value obtained by subtracting the light quantity value X _H corresponding to the density information value D _H of the H portion of the color original image obtained in the same manner from _n ).

y _n :% of halftone point set in a pixel of a color print image corresponding to an arbitrary pixel point (n point) of a color original image

y _H : halftone value set in advance in the H portion of the color print image corresponding to the H portion of the color original image

α: surface reflectance of an image expression medium for recording color print images

β: value determined by β = 10 ^-γ

k: numerical value determined by k = γ / (X _S -X _H )

X _s denotes the light quantity value X _S corresponding to the density information value D _S of the S portion of the color original image obtained using the characteristic curve of the recording medium.

γ: arbitrary coefficient

EXAMPLE

Hereinafter, the technical configuration of the color scanner of the present invention will be described in detail.

For convenience of explanation, the image information value and the original image are described here.

In the color scanner according to the present invention, the image information used to produce a color print image from a color original image is characterized by the fact that the image information correlates with the amount of light, rather than using image information values correlated with density as in the prior art. There is this.

In addition, in the present invention, the color original image is recorded or accumulated on a predetermined recording medium, and is also called a medium image. On the other hand, an image before being recorded or accumulated on the recording medium, i.e., being an actual object of duplication, is called an actual image (subject, real object, real diameter).

First, in order to obtain an understanding of the present invention, a method of adjusting the color tone will be described later in detail, and a gray scale conversion technique using the gray scale conversion equation will be outlined.

As described above, color scanner color separation apparatuses are extremely commonly used in the duplication of color print images, and the color separation operations by the apparatus include density information values obtained from color original images (including transmissive and reflective originals as media images). It is done on the basis of. More specifically, the production of color printing images is generally performed on the C, C, M, and Y plates based on density information values obtained through R, G, and B filters from a color original image (medium image). Plate (yellow) and BL plate (black) are produced.

However, the method of using the density information value of the color film (transmissive) document image (medium image) recorded on a recording medium called a photosensitive material as a color document image, for example, has a limitation (defect) as described above. On the other hand, in the present invention, as described above, the actual object of reproduction is not an image (medium image) recorded on a recording medium, but a literal color original image that forms the basis of the media image to the last, that is, the subject (real image) itself. It is based on the fact that the image information value to be used at the time of duplication should be based on the image information value correlated with the amount of light incident from the subject to the recording medium.

The above is the basic difference between the gradation conversion technology of the present invention and the prior art.

This is explained from another angle as follows.

In the color separation technique, a gradation conversion of a color gradation image of a continuous gradation (for example, a transmissive color film manuscript) to a color gradation image of a halftone gradation is required, but as described above, the correlation between the continuous gradation image and the halftone gradation image is defined. This is the color separation curve (gradation conversion curve). The conventional color separation curve is based on density information values formed on the D axis (concentration axis) of the photosensitive characteristic curve of the photosensitive photosensitive material which is a recording medium (a photographic concentration characteristic curve defined by the X-axis orthogonal coordinate system). It is set.

On the other hand, the color separation curve of the present invention is set based on the image information value correlated with the amount of light of the subject (actual image) on the X axis of the photograph density characteristic curve as described above. In other words, in the conventional color separation technology, the D-axis color separation curve is used, and the present invention can be said to use the X-axis color separation curve, and the two are basically different.

Next, a description will be given of a method for obtaining image information values, i.e., light quantity values, of each pixel of a color original image in the gradation conversion method of an image using the gradation conversion formula of the present invention.

First, the characteristic curve of photographic photosensitive material as a recording medium used for photographing a color original image (medium image), specifically, from the photograph concentration value (D = log Io / I) and the subject (real image, real image) A density characteristic curve representing a relationship between the image information value correlated with the amount of light incident on the photosensitive photosensitive material, that is, the logarithmic value of the exposure amount E = It is prepared. Next, the density characteristic curve is functionalized to obtain the light quantity value Xn from the density value Dn of any pixel (n point) in the color original image through the concentration characteristic curve. In this case, for example, the density characteristic curve corresponding to the recording medium provided as technical data from the photosensitive maker may be functionalized. When reasonably functionalized, the Dn value on the D axis can be easily converted to the Xn value on the X axis.

The concentration characteristic curve of Fig. 1 (manufactured by F Company, Fuji Chrome) is shown.

Table 1 shows the results of formulating the concentration characteristic curve of FIG.

In addition, as shown in Table 1, in order to formulate the density characteristic curve as accurately as possible, an attempt is made to formulate each division using eight divisions of the verticalization division. Needless to say, the more formalized divisions you get, the more accurate the formulas are.

In the formulating of the density characteristic curve, the scale (scale) of the X-axis representing the image information value correlated with the scale (scale) of the D-axis representing the density value of the color original image (medium image) and the log E of the subject (real image). We assume that this is the same and get a function to define the correlation between D and X.

This is a kind of agenda carried out from the following point of view, and the inventors think that it is reasonable. In this sense, the term agenda is used on the X-axis of FIG.

In other words, in the photographic density characteristic curve, the logarithmic value of log light quantity E (logE = logI × t) is fixed on the X-axis, but this is more algebraic as the discrimination characteristic of visual contrast is the same as the perception of the D-axis concentration. It is considered that the agenda regarding the scale is therefore reasonable.

Incidentally, in the present invention, the above-described scale is a kind of simple method, and needless to say, it is not limited to this.

The present invention is not based on the density value (D value) of a color document image (medium image) formed by photographing and recording a subject (solid image) on a recording medium (photosensitive material) as described above, but not on the subject (solid image). Is based on the image information value (X value) correlated with the amount of light represented by the X-axis incident on the recording medium.

As described above, as the concentration characteristic curves are shown in Table 1, the D value and the X value are correlated by the function of X = f (D), so that X can be easily obtained from the D value.

Next, the gradation conversion technique of the present invention uses the light quantity value (X value) determined as described above and the gradation conversion formula, and replaces the color separation curve (gradation conversion curve), that is, the X axis instead of the conventional D axis color separation curve. It is only necessary to obtain a color separation curve and perform gradation conversion of the image.

That is, under the predetermined density characteristic curve, the image information value X correlated with the amount of light of the pixel is obtained from the density value D at any pixel (n point) on the original image, and the value (X) is calculated according to the gray scale conversion equation. By substituting, the tone intensity value y, i.e., the dot area% value (hereinafter, simply referred to as the dot value% value) is calculated. What is necessary is just to input this% dot value into the dot generator (dot generator) of a color scanner, and to form a desired screen.

The derivation process of the gradation conversion equation of the present invention will be briefly described herein.

The gradation conversion formula for calculating the dot value (y) used in the production of the color print image, which is the above-mentioned halftone gradation, is a density curve (photo density, optical density), which is generally accepted.

D = log I / I = log 1 / T

I = incident light

I = amount of reflected or transmitted light

T = I / I = reflectance or transmitted light

Derived from.

The general formula of the above-mentioned concentration D is applied to plate making and printing as follows. Density (D ') in plate making and printing = log (I / I) = log unit area x paper reflectance / [(unit area-halftone area) x (reflectance of paper) + halftone area x ink surface reflectivity]

= log αA / [α {A-d + d +... … d)} + β (d + d… d)]

here

A: unit area

d: area of each dot in the unit area

α: reflectance of printing paper

β: The surface reflectance of the printing ink.

The present invention is based on the density formula (D ') relating to plate making and printing, and the basic concentration value (X) at an arbitrary sample point (pixel) (n point) of a color original image of continuous gradation corresponds to this. The gradation conversion formula is derived so that the theoretical value and the actual value coincide with each other in relation to the halftone value y of the halftone in the sample point of the color print image of the halftone gradation.

In the operation of the gradation conversion formula of the present invention, a half point value of 5% is used for y, 95% for y, 3% for y, and 90% for y in M and Y in general. In the operation of the gradation conversion equation, when the concentration meter measurement value is used for the concentration value and the percentage value (% value) as described above for y and y, the y value is also calculated as a percentage value (% value).

In the rotation of the gradation conversion formula of the present invention, it is also possible to use it by transforming as follows as well as using it by arbitrary processing, deformation, induction, and the like.

y = y + E (1-10 (Yy)

Provided that E = 1 / (1-β) = 1 / (1-10 )

The above modified example is β = 1.

This is to make the surface reflectance of the printing paper (substrate) used to express a color print image 100%. Arbitrary value may be taken as a value of (alpha), but it is good also as practical 1.0.

According to the above modification (α = 1.0), the y value can be set in the brightest part (H part) of the color print image as defined by the y value in the darkest part (S part), which constitutes a large feature point in the present invention. The above point is defined as X = 0 in the H portion of the color print image, and X = X-X in the S portion, that is,

-k * X = γ * (X-X) / (XX) =-γ

It is clear from becoming.

Thus, by using the gradation conversion formula (a variant of a = 1) of the present invention, it is possible to always set the y value and y value as intended, to the H and S portions of the color print image. This is extremely important for the user to evaluate or review the work results. In other words, if a desired value is set for y and y in a color print image, and the γ value is changed (where α = 1.0), various X-axis color separation curves (gradation conversion curves) are obtained. In addition, the image quality of the color print image produced below in these X-axis color separation curves can be easily evaluated in relation to the gamma value.

X-axis color separation curve (gradation conversion curve) of each color plate for multicolor plates (generally, four plates of C plate / M plate / Y plate / BL plate are used) using the above tone conversion equation of the present invention. To do this:

In the art, it is common practice to first set the color separation curve (gradation conversion curve) for the C plate as a reference, and then set the other color plates so that gray balance and color balance are maintained.

The above-mentioned gray balance oil and fat is important as a condition for reproducing neutral density (gray) by three color plates (C / M / Y board).

In the art, standard values shown in Table 2 below are generally employed to maintain gray balance.

In Table 2, M is a gray balance control point (hereinafter referred to as an intermediate point) set in the middle of the dynamic range (concentration range) of the H part to the S part.

In the art, it is usual for the M point to be set where 50% of the net dot% value of the C plate is shown. The main reason why the M point is set at 50% of the halftone point of the C plate is because it is widely recognized that the region of the halftone point value is a rich red domain of gradation.

From Table 2, it is understood in the art that the half point value of the C plate at 50% and the half point value of the other color plates (M / Y) at 40% are maintained at gray point to maintain gray balance. do.

As described above, the manufacturing conversion technique of the present invention does not use density information value Dn obtained from a color original image (medium image) in forming a color print image, but forms a medium image from a subject (real image). It is based on the premise of using the image information value (Xn) correlated with the amount of light incident on the recording medium and using the above-described gradation conversion formula, and is a color print image having a gradation characteristic faithful to a subject (real image), that is, gradation characteristics. It is possible to produce a color print image which has been changed to the desired one with work regularity, universality and elasticity.

Next, the core technical configuration of the present invention, that is, the incorporation of the tone adjustment technology with respect to the above-described tone conversion technology, in other words, the integration of the tone conversion technology and the tone management adjustment technology will be described. The reason for the integration of the gradation and color tone mentioned above was at the following point.

1) The above-described gradation conversion formulas proposed by the present inventors and also used in the present invention are based on the half-dot values of dots (dots) of all pixels ranging from H to S portions of the color print image as described above. Size) is an important route for faithfully reproducing the gradation characteristic of a color original image and adjusting it to a natural gradation characteristic for human vision.

2) The halftone value set for each pixel always has an influence directly related to both gradation and color tone (or density and color).

3) As a market requirement, there are cases that require not only 1: 1 reproduction (Hi-Fi reproduction) of color original images, but also emphasis, change, or correction of color tone of specific portions of the image, that is, the dynamic range of H-S portions. It is increasing. In the above-mentioned request, the customer or the designer, etc., present and designate the content of the request in percentage values by the color chart art (Color Chart, which will be described later).

4) Conventional color separation technology, in particular, in the case of the conventional color collection (color correction) to meet the requirements, for example, even if the hue of a particular portion is close to the required content, do not shift the state (gradation and hue) of the whole image. There are many cases which lose value as a product.

The color chart is a basic style (reference table) for color reproduction in which all colors are expressed by the density gradation of halftone dots using the printing process four primary inks. For example, DICGRAF-G Color Cha Art (March 1991) issued by Japan Ink Chemical Industry Co., Ltd.

There are various combinations as shown below as a combination of each color plate for color reproduction in the said color difference art.

1. Basic combination

There is a car art based on a combination of C (cyan) and M (magenta).

For example, print (C) on the vertical axis and (M) on the horizontal axis, respectively, with 12 gradations of 0% to 100% of halftone dots as the basic pattern, and Y (yellow) and BL ( This print was composed of overlapping prints. As Y and BL of the said constant dot% value, Y = 10% BL-10%, Y = 10% BL = 30%, Y = 50% BL = 10%, etc. are mentioned.

2. Combination of Others

(1) Combination of (Y) on the vertical axis and (M) on the horizontal axis

(2) Combination of vertical axis with (C) and horizontal axis with (Y)

(3) Combination of vertical axis with BL and horizontal axis with Y

(4) Combination of (BL) on the vertical axis and (M) on the horizontal axis

(5) Combination of vertical axis with (C) and horizontal axis with (BL)

As described above, the color tone on the color difference art is designated by the halftone percentage value of the color plate (C / M / Y / BL).

Therefore, it is necessary to say that as a color separation technology, a technique for quantitatively managing and adjusting all dot% values of each pixel must be secured as a color separation technology for a request for color tone change from a customer or graphic designer based on the color difference art. It is not a thing.

From the above background, the present inventors thought that the gray scale conversion formula can completely and quantitatively and reasonably manage and adjust the half-point values of the telephone stations ranging from H to S points. This is an opportunity for the development of color separation technology that integrates gradation and color tone by using gradation conversion as an important tool.

The color scanner of the present invention is characterized by incorporating a color separation technology incorporating the adjustment of the gradation and the hue adjustment in the gradation conversion unit, which is its core component, as described above. In particular, the color separation technique incorporating the color tone management adjustment in the present invention is significantly different from the conventional technique, and the advantages will be described below.

1. First, a color tone management point (M) for managing the color tone of a color print image is set at a desired portion between the H and S portions of the color document. In the present invention, as the symbol of the color tone management point M, the same symbol M as the halftone point M for maintaining the gray balance of Table 2 described above is used. This reflects that gray scale reproduction of the halftone region is an important point in color separation technology, and therefore also important in color reproduction. In addition, it is needless to say that the color tone management point M is not limited to the halftone point for maintaining the gray balance described above, and is good as a desired point between the H portion and the S portion.

The hue point M is represented by the light quantity value of the horizontal axis in the orthogonal coordinates of the vertical axis (Y axis: displays the net point% value) and the horizontal axis (X axis: displays the light quantity value), as shown in Examples and 3rd. do. In addition, since the said light quantity value correlates with the density value of a color original image, it may be represented by a density value.

2. Subsequently, the adjustment condition of the color tone at the designated color tone management point M is determined as the half-dot value of the desired color plate (C plate, M plate, Y plate, and BL plate).

The details of the adjustment (change) condition of the color tone are as described in the description of the color difference art.

3. The following steps prepare the color separation curve (gradation conversion curve) used to produce color plate images of color plates (C plate, M plate, Y plate, BL plate) using the above conditions and conditions. More specifically, it is preparation of the gradation conversion formula for setting the color separation curve for each color plate.

By the said process (1-2)

Light quantity value of color management point (M), for example M = 0.400

Adjusting condition of color tone, for example, C% cut value (50%), M% cut value (20%), Y% cut value (10%) and BL% cut value (10%) are set. do.

In addition, the halftone value (y, y) set in the H part and S part of each color plate sets a predetermined value or a desired value. In addition, the y-value y-values given as the above conditions are 5% and 95% for C and 3% and 90% for C and Y, respectively, as described in the section on operation of the gradation conversion equation of the present invention. (See Table 2).

Under the above conditions, the γ value of the gradation conversion equation used to determine the color separation curve for the color plate is determined.

For example, the r value of the gradation conversion equation for determining the color separation curve for the C plate is determined as follows.

In the gradation conversion formula

Solving by substituting X = 0.00, X = 1.00, Xn = M = 0.40, α = 1.00, y = 0 (%), y = 95% and yn = 50%, a value of γ = 0.45 is obtained.

Thereby, a gradation converter for setting the color separation curve for the C plate is prepared. The same is true for other colors.

4. The following step uses the gray scale converter having the? Value (0.45) described above to gray-scale the light quantity value Xn of all pixel points (n points) ranging from the H-S section to the color separation curve for the C plate ( Gradient conversion curve). In other words, in order to produce the color plate image of C board | substrate, color separation operation | movement can be performed using the said grayscale conversion formula for C board | substrates. The same is true for the other color plates.

The effectiveness of the color separation technique in the gradation conversion unit incorporating the gradation adjustment technique and the hue adjustment technique in the color scanner according to the present invention described above is demonstrated in the following examples.

Here, another feature and application field of the color separation technology incorporating the function of adjusting the gradation and hue in the color scanner of the present invention, in particular the gradation conversion unit, will be described.

The color separation technique of the gradation conversion unit of the color scanner according to the present invention is a color original image (medium image) obtained by recording, photographing or converting a subject (real image) to a desired recording medium using information transmission media such as light and electromagnetic waves. ) Can be applied to any field that wants to produce color print images.

Therefore, it goes without saying that the color separation technology of the present invention must be operated to be suitable for the system for producing each color print image.

First, a density characteristic curve indicating a characteristic curve of a recording medium, that is, a correlation between an image information value (light quantity value) correlating to an amount of light incident on a predetermined recording medium from a subject (actual image) and a density information value formed on the recording medium. In the definition of the above, the prescribed variable (factor) of the characteristic curve is not limited to the combination of the logarithmic value (light quantity value) and density information value of the exposure amount as described in the color original image. As the characteristic curve of the sensor which is the pressure medium (recording medium) of the image information of the subject (real image), the density information value (Dn value) correlated with the density and the image information value (Xn) correlated with the light quantity are interpreted in the widest range. The density characteristic curve (photoelectric conversion characteristic curve) is defined. The physical quantity representing the image information value correlated with this kind of density should be interpreted broadly. For example, synonyms include reflection density, transmission density, brightness, brightness, frequency, current, voltage value, and the like. The recording medium on which the subject (real image) is recorded may be any one of photosensitive materials for photography or photoelectric conversion elements such as two-dimensional CCDs, optical disks, magnetic disks, magnetic tapes, and photodiodes.

Needless to say, in the relation with the recording medium, the density characteristic curve which is a characteristic of the recording medium is called a photo density characteristic curve (for photosensitive photosensitive material), photoelectric conversion characteristic curve (for photoelectric conversion element), and the like. It's work. It goes without saying that the density characteristic curve is defined as a straight line of 45 degrees (degrees) in the rectangular coordinate system when the color original image is a reflective original.

The color scanner referred to in the present invention should be interpreted broadly as apparent from the above, and should be interpreted in the sense of all devices that perform color separation for producing a color print image.

Specifically, the color scanner referred to in the present invention is not limited to a variety of conventional stand alone type color scanners and total scanners, but is a separate color getter and color that operate at a workstation. It should be interpreted that in a color separation output device related to the production of a color print image such as a color setter, it means everything having a color separation function that combines the above-mentioned gradation and color tone. In addition, the mechanism of the color image may be a rotating drum type or a flat bed type.

In the present invention, the term "dot dots gradation" or "dot dots% value" is used, but duplication of color print images is not limited to those of dot dots.

For example, by the recent FM (Frequency modulation or Stochastic) screening method. Specifically, instead of the conventional method of modulating the area of the halftone dot (this is also called AM Amplitude modulation in relation to the above FM), the density modulation of the microdots (microdots) is performed by changing the state (gradation and hue) of a predetermined pixel. It also includes the form represented by.

Next, the structure of the gradation conversion unit which performs color separation by combining the above-described gradation and hue adjustment which are important components (mechanisms) in the color scanner of the present invention will be described.

1. In the present invention, the gradation conversion section is configured as follows, for example. (1) Correlation between density information values obtained from color original images recorded on a predetermined recording medium (sensor) and image information values correlated with the amount of light incident from a subject (real image) on the recording medium (sensor) Based on the density characteristic curve that defines the image information, the image information value and the image information electric signal value (which may be analog or digital) related to the density of the color original image (including hard and soft originals) may be used. And a mechanism (soft substitute) for calculating the image information value correlated with the amount of light, and (2) a mechanism for operating the tone conversion formula.

2. The configuration of the output section controls the current value, voltage value, or application time of the recording section (gigi head) of the device in correspondence with the calculation value obtained by the gray scale conversion formula, that is, the yn value (mesh point value), and the size of the mesh point (mesh point). It is good to comprise so that the color-printed image of the half-tone (dot halftone) adjusted as the gradation and hue are desired by changing% value) may be output.

For example, an original of a color print image which is a halftone gradation image using the color scanner of the present invention. That is, to produce a printing disc (color plate image), the sum of the gradation and the hue of the present invention may be combined with a color separation mechanism (gradation conversion unit) such as an electronic color separation device (color scanner, total scanner) commercially available in the art. This is achieved by incorporating a gradation converting section having a function.

More specifically, an image information electrical signal (voltage) obtained by irradiating a small spot light onto a color film original image (transmissive medium image), receiving the transmitted light (image information signal) by a photoelectric conversion unit, and converting the intensity of the light into a voltage intensity. The light source light for exposure is controlled based on the processed image information electric signal (voltage value) outputted from the computer, and then the spot light of the laser is exposed to the raw film to print the original plate (color plate image). You can use a well-known basic system for writing.

Then, the color film is reconstructed from the density information value of the color original image (medium image) recorded on the color film (recording medium) by reconstructing the computer processing unit for reconstructing the electrical signal of the image information of the color original image (medium image). The image information values correlated with the amount of light are obtained through the density characteristic curve of the (recording medium), and the software for outputting the dot value% (yn value) using the gradation conversion equation is simply incorporated.

As can be seen from the above description, the color original image (the medium image photographed and recorded on the recording medium called the photosensitive material) is processed by the scanner's image information import mechanism, specifically, the photoelectric conversion section, so that the image information value related to the density is obtained. do. Strictly speaking, since the photoelectric part has its own characteristic curve (photoelectric conversion characteristic curve), the image information of the color document image in the photoelectric conversion part is affected by the photoelectric conversion characteristic curve of the photoelectric conversion part. , Deterioration).

Therefore, it is preferable to exclude the influence of the photoelectric conversion characteristic curve, but this can be ignored. In other words, the image information of the color original image is affected (deterioration and deterioration) by the photoelectric conversion characteristic curve of the photoelectric conversion section.

Therefore, it is preferable to exclude the influence of the photoelectric conversion characteristic curve, but this may be ignored in consideration of the characteristics of the photoelectric conversion part.

As the software applied to the gradation converting section, the density information value Dn correlated with the density of the color original image is converted into the image information value Xn correlated with the corresponding light amount under a predetermined density characteristic curve. A general-purpose computer having a gradation conversion algorithm as software and having an A / D (analog-digital conversion) and an I / F (interface) of D / A, and an electric circuit embodied by a general-purpose IC using algorithms as logic. It can take various forms such as PAL, gate array, caster IC, etc., which are embodied by internal logic of algorithm, electrical circuit including ROM containing algorithm calculation result.

In particular, in recent years, modularization has developed, and an arithmetic mechanism capable of performing gradation conversion of an image based on the gradation conversion formula of the present invention can be easily manufactured as a module such as a dedicated IC, LSI, microprocessor, microcomputer, or the like. There is a number.

Then, when the spot light used for photovoltaic use is sequentially scanned while dividing into points, the laser exposure part that irradiates a laser light on the raw film is also synchronized with this, and the halftone gradation having a dot% (y) derived by the gray scale conversion equation is obtained. A printing disc (color plate image) in which the gradation and color tone of the light are manipulated as desired is reasonably produced.

EXAMPLE

Hereinafter, an embodiment of a color scanner of the present invention will be described in detail with reference to the drawings. In addition, the color separation method (gradation conversion method integrating the adjustment of gradation and hue) using the color scanner of the present invention will be described in detail.

In addition, the color scanner of the present invention can be said to streamline and simplify its configuration and improve its added value by applying a new tone converter to an existing color scanner as shown below.

2 is a block diagram showing the configuration of a color scanner as a first embodiment of the present invention.

As shown in the drawing, the existing color scanner (rotary drum type) to which the present invention is to be improved consists of the following four blocks.

(1) A detection unit 1 which reads image information of a color original image. The detection unit 1 reads density information values in the color original image by the R / G / b adaptation filter.

(2) The color separation unit 2 for converting the output signal of the detection unit 1 into color separation signals of C, M, Y, and BL, and the BL (weak) component hereinafter are denoted by the symbol K.

The color separation section 2 is a BM 8 (basic one-color correction circuit that corrects deviations from an abnormal color of C / M / Y as a basic mask circuit) or CC 9 (two-color correction as a color collection circuit). Circuit).

(3) The tone adjusting unit 3, which is mainly a tone correction circuit in the existing color scanner, is used as a circuit for determining how the state of the halftone between the H and S portions is performed.

(4) The output part 4 which exposes the raw film by a laser beam based on the output signal of the said adjustment part 3.

In the present invention, the four-block detection unit 1, the color separation unit 2, and the output unit 4 use the mechanism and configuration of a conventional color scanner as it is.

In other words, the gradation adjustment section 3 is the object of improvement of the present invention.

Strictly speaking, the gradation conversion unit based on the gradation conversion formula for integrating the gradation and color tone adjustment of the present invention for color separation is related to the improvement of the function of the color separation unit 2.

Therefore, it can be said that the color scanner of the present invention is configured by changing the configuration of the conventional tone conversion unit to the tone conversion unit of the present invention while using the color separation unit 2 of the existing color scanner.

The structure of the color scanner of this invention is demonstrated concretely below.

The detector 1 detects transmitted or reflected light of each part of the color original image 5, such as a photoelectric converter, and outputs signals of R, G, B, and USM as current values, and converts the signals into A / D converters. In (6), the signal is converted into a voltage signal.

The color separation unit 2 converts the voltage signals of the R, G, B, and USM signals of the detection unit 1 into logarithms in the log amplifier 7 and converts them into concentrations, and the C / M in the basic masking (BM) 8. Separate the gray component (primary color component) of / Y and the gray component. Next, in the color collection (CC) section 9, the C plate component, M plate component, and Y plate component are controlled for each original color of R, G, B and C, M, and Y. In the UCR (Under color remoal) or UCA (Under color addition) of the / UCA unit 10, the ratio expressed by three color plates of C, M, and Y and the ratio expressed by K plate are determined.

That is, in the color scanner of the present invention, the color original image 5 (the object to be reproduced) (such as a color print or a color transmissive document) is first composed of a photoelectric conversion unit, a solid state imaging device (CCD), or the like in the conventional detection unit 1. Image information of each color (R, G, B) is detected by the image information reading mechanism, and the density information value Dn is obtained by color separation in the color separation unit 2 to produce a color print image. This is calculated | required for each color (C, M, Y) component (basic color component) as mentioned above.

The density information value (Dn) is an image information value (X) correlated with the amount of light using a photographic density characteristic curve of a recording medium of a color original image, for example, a photosensitive material, that is, a basic light quantity value (X). Needless to say that it is converted. In addition, in order to obtain image information correlated to the above-described light amount, it may be performed by software or hard-hat (not shown).

In the present invention, the function of obtaining the image information value X and the basic light amount value X correlated with the light amount from the above-described density information value D may be incorporated in the gradation adjustment section 3 described below. This is based on the idea that the gradation adjusting section 3 operates an gradation conversion algorithm and finishes the calculation function in one because pixel information correlated with the light quantity value is also obtained by a predetermined algorithm. It goes without saying that the present invention is not limited to this method.

After the C, M, Y, and K components are obtained as described above, in the prior art, the halftone execution area of each color component in the gradation control section of the gradation adjusting section 3 is set to ce ', me', ye ', and ke. 'Is inverted and converted by the inverse log converter.

On the other hand, in the color scanner of the present invention, the above-described conventional gradation control unit is replaced by the gradation conversion unit 11 which integrates and adjusts both gradation and hue based on the gradation conversion formula of the present invention, where C, The conversion from M, Y and BL to ce ', me', ye 'and ke' is performed.

Incidentally, the gradation converting section 11 is shown only as a converting section 11 in the figure.

The gradation converting section 11 has an algorithm for calculating the light quantity value X from the density value D using the density characteristic curve of the recording medium recording the color original image, and a gradation conversion calculation algorithm.

And ce ', me', ye ', and ke' are obtained by applying the gray scale conversion formula to each of C, M, Y, and K.

The gradation converting section 11 holds a gradation conversion algorithm as software, a general-purpose computer having A / D and D / A I / F (interface), and an electric circuit embodied by a general purpose IC using an algorithm as logic. The internal logic of the algorithm can take various forms such as PAL, gate array, and castam IC.

The dot effective area ratio obtained by the gradation converting section 11 is input to the color channel selector 12, where ce ', me', ye ', and ke' are selectively output one after another. This output value is subjected to A / D conversion by the A / D conversion unit 13 and input to the output unit 4.

The laser beam is controlled in the dot control unit 14 based on the output of the gradation adjusting unit 3 from the output unit 4.

The laser beam controlled from the output unit 4 is irradiated onto the raw film, and the printed plates of the color plates C, M, Y and BL plates are produced.

The following three steps of experiments were conducted to examine whether the gray scale and color tone of the color print image can be reasonably managed and adjusted using the gray scale conversion formula of the present invention as an important tool.

(1) basic experiment

(2) Application experiment

(3) Practical application experiment

In order to carefully examine the effects and effects of incorporating tone control on the tone conversion equation, a useful tool as a tone conversion technique, two methods were put into each of the above three steps.

(1) Experiment A: Experiment of adjusting the halftone value of both color tone management point (M) and S part of three color plate images (C plate / M plate / Y plate)

(2) Experiment B: Experiment to adjust only the M points of three color plate images (C board / M board / Y board)

Determination method of light quantity value of M point M point and γ value for color plate

(1) Color management point (M)

The color tone management point M (see FIG. 3) is a point of halftone value of the C plate halftone gradation image (color plate image) more precisely than the halftone that is widely adopted due to the preparation of the gradation in the prior art. Set.

This is in accordance with the standard for maintaining a proper gray balance generally employed in the art.

Needless to say, in the present invention, it goes without saying that the color tone management point M is not limited to 50% of the dot value% of the C plate.

(2) Light quantity value of hue management point (M)

The value of the light quantity value of the color tone management point M was determined by the color separation curve (gradation conversion curve) for C plates.

That is, in the gradation conversion equation for determining the color separation curve for C plate, the dot range: 0 to 95% (y = 0%, y = 95%)

γ value: 0.45

X = 1.00, X = 0.00 (X-X = 1.00) (Note)

X value (light amount value in color tone management point) was calculated by substituting the condition of y = 50 (%) (this is the percentage of halftone point of said color tone management point M) into the tone conversion formula.

In other words, the above conditions were substituted into the gray scale conversion equation to solve the following equation. The result is X = 0.40.

50 = 0 + [(1-10 ) (95-0) / (1-10 )]

In general, the dynamic range (X-X) of the light quantity value obtained from the color original image (medium image) is not 1.00, but a value obtained by normalizing the dynamic range to 1.00 is used here. Needless to say, there is no problem in image processing because the image quality is changed relative to each other even when the dynamic range of the region is normalized to 1.00.

(3) Determination method of gamma value for determining color separation curve for color plate (C / M / Y / BL)

In the following experimental example, the value for setting the color separation curve for C plate is using a value of? = 0.45 as described above.

For other color plates,? Values for setting the respective color separation curves (gradation conversion curves) must be determined in accordance with the contents of the color tone adjustment conditions.

For example, in the case of the M plate (the light quantity value is 0.40) at the color tone management point M (the light quantity value is 0.40), the following formula can be obtained by solving the following equation when the M dot value of the M plate is 20% and the use range is 0 to 68%. The following solution is γ = 0.20.

20 = 0 + [(1-10 ) (68-0) / (1-10 ]

In this experiment, the light quantity value of the said color tone management point M and (gamma) value for each color plate are calculated automatically, and the software which automatically prepares the desired color separation curve was used.

(1) As a color original image, an image of a brown pottery jar of standard quality photographed with a 4x5 cover color film manufactured by E, K, Co., Ltd. was selected.

(2) As a color scanner, a modified one of the digital color scanner 455 type tone conversion unit made by ISOMET (USA) was used. That is, the software calculates the light quantity value (normalized light quantity value) through the photo density characteristic curves (12 characteristic curves of representative photosensitive materials such as Fuji chrome, Agpa chrome, and octachrome) from the concentration values. Software for color management using a tone conversion formula and software for calculating color separation curves. A tone conversion unit having a built-in gray scale conversion unit was used in the digital color scanner 455 type manufactured by ISOMET.

(3) AGFA S712P was used as a film for color separation.

(4) DUPON's chromamarine system was adopted for color correction.

Basic experiment

This experiment aims to confirm whether or not the tool of the present invention gradation conversion has a function to reasonably adjust the color tone of a color print image.

In particular, it was confirmed whether or not the color tone could be reasonably prepared while maintaining the tone.

Table 3 shows the plate design data for each color plate for the adjustment and adjustment of the color tone for the basic experiment.

(Note 1) Experiment A was previously performed by designating the% of halftone point of the S part, followed by the following experiment (1) to obtain the halftone point of M point (tone control point). Moreover, the standard mesh point% value of following formula (2) is shown in Table 2.

% Dot value of M point = (standard% dot value of M point) X (% dot value specified in S part) / (standard% dot value of S part)... … (One)

(Note 2) Experiment B employs the value of Experiment A as the half-point value of M point and adopts the standard value (Table 2) as the half-point value of S part.

(Note 3) Since the catch light portion is selected as the H portion of the color original image (jar), the percentage of halftone dots of the H portion of all the color print images is "0" (zero).

The four experimental results of the above basic experiments were all as expected in light of the plate making practice. This indicates that the color tone management method using the tone conversion formula of the present invention has a reasonableness.

In addition, the contents of the four color correction images obtained from the basic experiment are as follows.

(1) All four points reproduced well the tone (density gradation) in the entire dynamic range of the H part to the S part, and the volume of the intermediate tone was also appropriate for human vision.

(2) The color tone of the jar is blue in experiment A (No. 1 to No. 2), and blue in the halftone area in experiment B (No. 1 to No. 2), and the original image in S part. It was brown. In addition, their color was in keeping with the trial practice.

Incidentally, the gamma value for setting the color separation curve for each color plate of Experiment A (No. 1 to No. 2) and the dot% value (calculated value) at M point are as follows.

The gamma value of the BL plate is gamma = -0.25.

The outline of the basic experiment and the color separation curve (gradation conversion curve) for each color plate used in Experiment A (No. 1) and Experiment B (No. 1) are shown in FIG.

(A) in the figure is a combination of color separation curves employed as a standard in the art because of the gray balance fat and oil. His trial design data is given in Table 2.

(A) in the figure shows the combination of the color separation curves (gradation conversion curves) of the respective color plates of Experiment A (No. 1).

[Application Experiment]

This experiment aims to confirm whether or not the color tone management method using the gradation conversion formula of the present invention has a function to reasonably adjust and manage the color print image by performing color separation experiments in a manner closer to the routine color separation operation.

In the present experiment was a management point (M ₁₎ of the color tone, to the point that a halftone dot% value of 50% on C engraving.

In addition, the basic scale which specifies the adjustment content of the color tone (specific content of correction or change of color tone required by the user, etc.) in the color tone management point M ₁ as the halftone percentage value of each color C / M / Y of each color image. DIC GRAF-G color car art (2nd March, 1991) manufactured by Japan Ink Chemical Industries, Ltd. was adopted.

In this experiment, six kinds of colors were selected from the color difference arts.

In Table 4, designated network point% values for six types of color and color tone adjustment selected from the above-mentioned "DIC GRAF-G color difference art" are shown.

In the color difference art, the six colors are displayed in 12 steps between 0 and 100 as C / M dot concentrations, and Y / BL (constant dot concentrations, for example, as shown in Table 4). Similarly, having a dot density of 10% or 50%) is shown as a color superimposed on the printing.

Therefore, the designated mesh point% value for color tone adjustment can be easily designated in the Dongcha art, and Table 4 shows its designated mesh point% value.

Needless to say, it is the purpose of this experiment to examine whether or not the color designated by the above halftone value is faithfully reproduced on the color plate image without causing deterioration of the gradation.

Plate making design data for this experiment prepared based on the data of Table 4 is shown in Table 5 below.

(Note 1) In this experiment, the designated mesh point% value for color tone adjustment of Table 4 was employ | adopted not to mention.

(Note 2) In experiment A of this experiment, the% value of the netting point for the M / Y plate of the S part was calculated | required by following formula (2).

As for the C plate, the value (95%) of Table 2 (gray balance maintenance standard value) was adopted. In addition, the standard mesh point% value of following formula (2) is shown in Table 2.

In addition, when the calculation result by following formula (2) exceeds the standard mesh point% value, it was assumed that the standard mesh point% value was adopted.

% Half point value of S part = (standard half point value of S part) X (% half point value specified by M) / (% standard half point value of M)... … (2)

(Note 3) Since the catch light portion is selected as the H portion of the color original image (jar), the percentage of halftone dots of the H portion of all the color print images is "0" (zero).

(Note 4) The BL plate (wet plate) was a Skelton type, i.e., a starting point (SP) as the M point and an end point (EP) as the S part according to a conventional method.

Moreover, experiment A was 80% and experiment B was 70% of the maximum net point% value of the BL board put into S part.

(Application Experiment) Plate Making Design Data for Color Adjustment

The results of the application experiments were all as expected in the same manner as in the basic experiments.

The color tone at the color management image (M) obtained as a color print image is completely matched with the color tone on the color difference art as a basic scale, and the color tone as well as the color tone are natural for human eyes over the total dynamic range of the H-S part. Was.

In other words, it was confirmed from the results of the above applied experiments that the color separation technology requiring the tone conversion formula of the present invention has a rationality in integrating the tone adjustment and the tone adjustment in performing color tone management adjustment.

Practical Application Experiment

In this practical application experiment, recently, the printing designers used standard color original images, and the finished state of the color print images reproduced by all means was in blue, dark green, light green, pink, sepia, etc. In view of the increasing number of work to be changed in the present invention, in view of the fact that the above-described color tone of the image as a whole must be subjected to a plurality of complicated and complicated working processes based entirely on empirical functions. The effectiveness of the control adjustment method of the gradation and color tone of the present invention for the work of was tested.

In other words, by applying the management adjustment method of the gradation and hue of the present invention, it is decided whether or not the gradation of the image can be reasonably managed as well as changing the hue of the image as a whole.

The color original image for the experiment was selected from among 4 x 5 size transmissive color originals manufactured by F Company, which is recognized as a standard color original in the art. Specifically, as a standard color original image, one having a young female image containing various colors such as red, blue, green and yellow purple and several kinds of band materials (metal, cloth, paper, etc.) was selected.

On the other hand, experiments were simultaneously performed on a 4 × 5 transmissive target (color document image produced by the ISO standard) manufactured by AGFA, which is widely used as a reference target in the art.

The color tone of the finish of the color print image to be reproduced was changed to blue tone.

Specifically, in the 29th aspect of the DIC GRAF-G color difference art, the color tone was controlled by the designated colors of 50% C, 30% M, 10% Y, and 30% BL.

In addition, the apparatus, material, etc. which were used for this experiment are as having mentioned above.

This experimental plate design data is shown in Table 6 below. Table 7 shows the tone curve setting data for the C plate.

In addition, the following points were considered in drawing up the plate design data of Table 6 while referring to the results of the above application experiments.

(1) Consider using the BL's image rendering ability and effects fully to suppress the red, gray, green, yellow, and purple colors in the color original image as natural while giving emphasis to the blue-to-finish finish of the entire image. It was.

(2) For this reason, SP (start point) of BL board was determined to the site | part of the% of dot value of C board | substrate, and it was set as 10% in management point M, and the maximum half-hole% value in S part was 95%. The gamma value for setting the BL plate color separation curve, that is, the gamma value of the gray scale conversion equation, was set to 0.10.

As a result of the experiment, both color tone and gradation of the image were obtained as the color print image as planned in the plate making design.

In other words, the portrait of the young woman in the color manuscript is a blue color tone and extremely natural. The overall hue of the female figure was blue and sufficient to reproduce the original skin color. When the above experimental results are described more precisely, the hue is the same blue tone as the color tone specified on the color chart in the H-medium tones, and there is a feeling that magenta (M) color remains in the S-area.

This is because, as evident from the plate design data (data) of Table 6, a large percentage of half point values were specified (68%) in the S portion of the M plate, and the experimental results were in full agreement with this.

In addition, the colors such as red, green, yellow, and purple are also softly suppressed, so that they do not have the state of the whole image and a feeling of discomfort.

In addition, the whole gradations ranging from the H part to the S part are not damaged at all, and because they express the unique gradation change of materials such as metal and fabric flowers through the overall blue hue, these materials can be clearly identified. At the same time, their details were well reproduced.

In addition, the color print image of the blue tone obtained from the standard target of AGFA also had a rich gradation in spite of the overall blue image.

In other words, the blue-colored state received from the whole image was extremely natural and harmonious in the same shape as seen through the blue filter. This demonstrates that the conversion of the gradation is reasonably performed also in the overall conversion process of the color tone.

Hereinafter, another embodiment of the color scanner of the present invention will be described with reference to the drawings.

4 is a block diagram of a color scanner according to a second embodiment of the present invention.

In the color scanner of the second embodiment, the conventional inverse log converting section 15 is used as it is, and therefore, in the grayscale converting section 11 in the form of logarithms, ce ', me', ye ', and ke. Is printed.

As a result, the color scanner of the present invention is realized by modifying a component (gradation conversion unit), which is one of the conventional color scanners, to have the function of the gradation conversion unit 11 of the present invention.

5 is a block diagram of a color scanner according to a third embodiment of the present invention.

In the third embodiment, the conventional gradient control (IMC) unit 16 is left as it is, and the inverse log converter 15 is disconnected from the gradient control unit 16. In the same manner as in the second embodiment, the tone converter 11 for outputting ce ', me', ye ', and ke' in logarithmic form is employed. The tone converter 11 takes signals C, M, Y, and K from the previous stage of the gradient controller 16, and outputs the value of the tone converter to the inverse log converter 15.

6 is a block diagram of a color scanner of the fourth embodiment of the present invention.

In the fourth embodiment, the conventional inverse log converter 15 and the color channel selector 12 are connected, and the tone converter 11 is C, M, Y from the previous step of the gradation controller 16. , The K signal is applied to the color channel selector 12 directly to ce ', me', ye ', and ke', without being constrained to the conventional system. We can get ce ', me', ye ', and ke'.

In the same manner as in the third embodiment, the color scanner of the present invention can be configured with a slight modification of the conventional system.

7 is a block diagram of a color scanner according to a fifth embodiment of the present invention.

In the fifth embodiment, the whole gray scale adjusting section 3 is constituted as a new gray scale converting section 11, and the gray scale converting section 11 uses both the gray scale and the color tone based on the gray scale conversion formula of the present invention. Integrate color separation.

In this way, by remodeling the entire gray scale conversion unit, smooth integration and converging with other image systems can be achieved, and the manpower per system can be increased while speeding up the processing of image information or making the device compact.

[Effects of the Invention]

The color scanner of the present invention is capable of color separation by integrating both gradation and color tone using a specific gradation conversion formula, which is a core component of the gradation conversion unit.

The fact that this adjustment of gray and hue can be integrated quantitatively and reasonably is difficult in the prior art, and is a key point of the present invention.

In the prior art, in order to respond to a request for a special committee with a high market demand (high demand), a specific part, that is, to adjust a color tone (correction or change of color tone), it is not possible to quantitatively adjust the color tone. Not only that, but the unevenness of the color tone between the site and the other part and the state (gradation and color tone) of the image coalescing were distorted, so that high quality color reproduction images could not be produced.

On the other hand, the color separation (gradation conversion) technology incorporated in the heart of the color scanner of the present invention can completely quantify the tone adjustment and the tone adjustment by adopting a specific tone conversion formula and its operation, and thus color suitable for the purpose. Original images can be color-separated, and high-quality color printed images with hue adjustment as well as reproducibility of gradation can be efficiently produced.

That is, the color scanner of the present invention brings the following excellent effects.

(1) It can reasonably cope with the demand for the quality of color printing images in a highly, complicated and diversified market.

(2) Since the production of color print images, especially the color separation work, is practiced quantitatively and reasonably, it has a remarkable effect on productivity improvement, shortening of working time, efficient utilization of equipment, saving of consumable materials, and reduction.

(3) In the production of color print images, it is possible to open the way for rational use of emotion and artistry. These enable the combination of sensitivity and artistry to the industrial production method required in the printing industry, and can contribute to the activation of image related industries such as the printing industry.

Claims (7)

A color scanner for producing a printing plate for producing color print images of halftones by converting image information of a color original image of continuous gradation in a gradation conversion unit of a color scanner, wherein the gradation conversion unit comprises: (1) a color original image; The characteristic curve of the recording medium recording the density value (D characteristic curve defining the relationship between the light quantity value (X value) incident on the recording medium and the concentration value (D value) formed on the recording medium in a DX rectangular coordinate system) (X) to obtain a light quantity value (X value), (2) converting the light quantity value (X value) using the following gradation conversion formula to obtain a dot value (Y value), and (3) As the color tone adjusting step used in the gradation conversion, the color tone adjusting step (3-1) adjusts the color tone of the color print image to a desired portion between the H portion (the brightest portion) and the S portion (the darkest portion) of the color original image. Set the color management point (M ₁ ) for management, (3-2) In the color tone management point M ₁ , the condition for adjusting the color tone is defined by the percentage of _half point of the desired color plate (C plate, M plate, Y plate, BL plate), and (3-3) the color tone management point (M). ₁ ) the dot value of the color plate reflecting the light quantity value and the adjustment condition of the color tone in the above step, and the desired dot% value set in the H portion and the S portion are substituted into the following gradation conversion equation to determine the γ value and the H portion of the color plate. A gradation conversion formula is provided for converting the light quantity value of the pixel reaching the S portion to the halftone value, and (3-4) the light quantity value of each pixel for each color plate using the gradation conversion formula for the color plate in which the γ value is determined. The tone is controlled and adjusted simultaneously with the gradation conversion. The color scanner, characterized by comprising a step and adjusting the color tone. Gradation Conversion Yn = y _H + [α (1-10 ^-kX ) (y _S -y _H ) / (α-β)] In the gray scale conversion _formula , the meaning of each symbol is as follows. X: (Xn-X _H ) is represented. That is, the density value of the H portion of the color document image obtained in the same shape from the light amount value Xn corresponding to the density value D ₁ of any pixel point (n point) of the color document image obtained using the characteristic curve of the recording medium. The basic light quantity value obtained by subtracting the light quantity value X _H corresponding to (D _H ) is shown. yn: halftone value set to the pixel of the color print image corresponding to an arbitrary pixel point (n point) of the color original image, y _H : preset to the H portion of the color print image corresponding to the H portion of the color original image % Of dot value, ys:% of dot value preset in S part of color print image corresponding to S part of color original image, α: surface reflectivity of image representation medium for recording color print image, β: β = A value determined by 10 ^-r , k: A value determined by K = γ / (Xs-X _H ), where Xs is a density value of the S portion of the color document image obtained using the characteristic curve of the recording medium (Ds Represents a light quantity value Xs corresponding to γ: arbitrary coefficient. The color scanner according to claim 1, wherein the color document image is a color film (transmission type) document image. The color scanner according to claim 1, wherein the color document image is a color print (reflective) document image. 4. The color scanner according to claim 3, wherein the characteristic curve of the color print (reflected) document image is defined in a relationship of density value (D value) and light amount value (X value) of 1: 1. The color scanner according to claim 1, wherein the color tone adjustment is performed by fixing the dot value of the Y and BL plates and having the dot value of the C and M plates. The method of claim 1, wherein the color tone management point (M ₁ ), X _S- X _H = 1.0 (normalized light value range), y _H = 0% _, y _S = 95%, r = 0.5 under the initial conditions The color scanner according to the determined C-gradation conversion curve (color separation curve), wherein the half point value is set to 50%. The color scanner according to claim 6, wherein the color tone management point (M ₁ ) is set at a portion of M ₁ = 0.400 (light quantity value).