JPS60216351A - Automatic setting method of gradation processing condition - Google Patents

Abstract

PURPOSE:To obtain a color taste by performing an arithmetic correction of an inputted reference gradation conversion curve so that it approximates to a reference output value corresponding to the density or mesh-point area rate of a color patch specified for the input density of a specific part on an original, and performing image processing. CONSTITUTION:A highlight and shadow density signal P1 and a reference gradation convesion curve signal P2 are inputted from a parameter input part 15 to an arithmetic part 16 and the input density signal P3 of the specific part on the color original is also inputted to the arithmetic part 16. Further, a color patch number P4 specified as the finish color taste of the specific part is inputted from the input part 15 to the arithmetic part 16. A reference density signal P5 is read out of a reference density table 17 according to the signal P4, and the signals P1, P2, P3, and P5 are inputted to a curve correction arithmetic circuit 18. The circuit 18 performs an arithmetic correction of the signal P2 for the signal P3 so that it indicates a value near the signal P5, and stores the result in the gradation conversion table 7a in an image processing circuit 7. Thus, gradation processing condition for finishing the specific part of the image to the desired color taste is set automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a method for automatically setting gradation processing conditions in a color image input/output system to accurately finish a specific part on a final output image to a desired color tone. It is something.

(Technical Background of the Invention and Prior Art) In color images such as color printed matter, it is sometimes desired to finish not only the overall tone but also the color tone of a specific part extremely accurately. For example, the color tone of the skin in a human image, the color tone of a product in a product catalog for automobiles, etc.

In a color image input/output system using a color scanner or the like, the final output image (in a color image input/output system that outputs the final image directly from an image output device, this is the image; in a color image input/output system that performs color platemaking, is a printed material printed using a created plate). Conventionally, color correction (which is performed by inputting the input density signal of each color to an image processing circuit) has been used to change the color tone on a
Color correction) and gradation processing are known.

To explain the above gradation processing using a color plate making system using a normal color scanner as an example, first, the scanner input head is manually moved to a specific part of the document on the scanner drum, and each color (usually yellow, yellow, etc.) in that specific part is
Check the finished density (magenta, cyan, black), or in this case, the halftone area ratio display, and adjust the gradation processing condition (gradation conversion curve) correction knob of the image processing circuit to obtain the desired halftone area ratio for each color. I was trying to operate it.

However, setting the gradation processing conditions as described above is done manually by the operator relying on intuition, which is time-consuming and requires skill. It has a number of drawbacks, such as the difficulty in predicting the color tone, and the fact that gradation processing condition settings tend to vary between individuals, making it impossible to guarantee a uniform finished color tone.

Recently, attempts have been made to automatically set a gradation conversion curve from the density histogram information of a document, as shown in, for example, Japanese Patent Application Laid-Open No. 58-5744. Even if you set
As mentioned above, for a specific portion where the color tone needs to be precisely finished, the gradation processing condition correction operation as described above must be performed to readjust the gradation conversion curve.

(Object of the Invention) The present invention has been made in view of the above-mentioned circumstances, and is an object of the present invention to provide a color image input/output system using the above-mentioned color scanner, etc., which uses gradation to accurately finish a specific part in a desired color tone. It is an object of the present invention to provide a method for automatically setting gradation processing conditions, which allows processing conditions to be set simply and without individual differences without requiring any skill.

(Structure of the Invention) The method for automatically setting gradation processing conditions in the color image input/output system of the present invention is such that the gradation conversion curve is automatically corrected by inputting a code of a color batch to be referred to as a color sample. In other words, as in the color plate making system described above, each inclusion angle signal from an image input device that separates and reads a color original is input to an image processing circuit, and each color is processed for each of these signals. In a color image input/output system that performs gradation processing based on gradation processing conditions and inputs each color output density signal after gradation processing to an image output device, a large number of color patches are created by changing the density of each color. At the same time, each color reference density signal corresponding to the density of each color in these color batches is stored in a storage means in correspondence with an input code unique to each color patch, and the color tone and tone of a specific color patch are recorded on the final output image. Input density signals for each color of a specific part of the document to be finished with a similar color tone, reference density signals for each color of the specific color batch read from the storage means according to the input code designation of the specific color batch, and each predetermined color. and the data of the reference gradation conversion curve are input to a calculation means, and the calculation means converts the reference gradation conversion curve of each color to indicate a value near the output density signal of each color with respect to the input density signal of each color in the specific portion. Correct the calculation to
The data of the corrected gradation conversion curve after this correction is transferred to the image processing circuit and set as the gradation processing condition.

(Embodiments) Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows an example of a color image input/output system that automatically sets gradation processing conditions using the first embodiment method of the present invention to accurately finish a specific part on a final output image to a desired color tone. It is something.

A color original 2 set on the peripheral surface of a rotating input drum 1 is color-separated and scanned by an input optical head 3 equipped with a color separation filter, and image signals of yellow, magenta, and cyan are obtained through a photoelectric converter 4. Y, M, and C are converted by a logarithmic conversion circuit 5 and an AD converter 6 into digital color input density signals=I Y , I M , and I C . Note that the signal processing after the photoelectric converter 4 is performed in a series for each color, but since the signal processing is performed in the same way in each series, in the diagrams and the following description, each series is not particularly separated, and the same information is used for each series. explain.

The above color input density signals IY11M and IC are subjected to gradation processing in the image processing circuit 7 based on a gradation conversion table which will be described in detail later, and are outputted as respective color output density signals OY and 0M1QC. These color output density signals OY, OM,
The QC is passed through a light amount control signal converter 8 and a DA converter 9,
It is converted into analog light amount control signals Y', M', and C'. These light amount control signals Y', M', and C' are input to a modulator 11 that modulates the recording light from the exposure light beam 10.
Recording light modulated according to these light amount control signals Y', M', and C' is output from the exposure head 12, and a color image as a final output image is formed on the film 14 on the rotating output drum 13.

The above-mentioned gradation conversion table is set by taking in data of a reference gradation conversion curve (which may be selected as appropriate depending on the situation) inputted from the parameter input section 15 via the calculation section 16. However, if the data of the standard gradation conversion curve is set as a gradation conversion table as it is, there may be cases where a specific part of the final output image of the film 14 where it is desired to be precisely finished with the desired color cannot be finished in that way. be.

7- A method according to the first embodiment of the present invention for automatically setting the gradation conversion table by correcting it so as not to cause such a problem will be described in detail below.

In the method of the present invention, first, color batches 101, 102, 103, . . . , 201, .
202, 203... are prepared. As shown in the figure, a large number of color patches are created with different densities of Y, M, and C colors, and the operator selects the optimal color for the specific portion from among the colors of these color patches. These color patches 101.102.103..., 201.20
2.203... are systematized by main hue to facilitate searching, and are organized into, for example, "skin color chart" 51, "gray chart" 52, etc., as shown in the figure.

Then, each color reference density signal carrying each color density that forms the tint according to each color batch on the final output image is stored in a reference density table 17 in the calculation unit 16 as shown in FIG.
In, each color patch 1oi, 102.103...
・, 201.202.203... number 0101
, 0102.0103..., 8-0201.0202.0203....

Next, the gradation processing condition setting operation will be described with reference to FIG. 3, which does not show the flow of signals within the calculation section 16. After setting the color original M2 on the input drum 1, the signal P1 carrying the highlight and shadow density of each color and the data P of the reference gradation conversion curve of each color are input from the parameter input section 15.
2 is input to the calculation unit 16. Next, the input optical head 3 is moved to the specific portion on the color original 2, and each color input density signal P3 of the specific portion is input to the calculation unit 16.

At the same time, the number of the specific color batch selected as the finish color of the specific portion is inputted to the parameter input section 15 as an input code, and as a result, a signal carrying the number of the specific color batch is sent from the parameter input section 15. P4 is input to the calculation unit 16. When this color patch number signal P4 is input, each color reference density signal P5 unique to this designated specific color batch is read out from the reference density table 17.

The readout output density signal P5 of each color, the highlight and shadow density signal P1, the data P2 of the reference gradation conversion curve, and the input density signal P3 of each color of the specific portion are input to the curve correction calculation circuit 18, and the reference gradation The conversion curve is computationally modified. This modification of the reference gradation conversion curve will be explained with reference to FIG.

Note that this modification of the gradation conversion curve is performed in the same way for each color signal, so a specific explanation for each color will not be given below. Assume that the reference gradation conversion curve defined from the reference gradation conversion curve data P2 is Q shown by a solid line in FIG. In addition, three specific portions 11, I2, and I3 that generate input density signals between the highlight density and the shadow density are specified, and the input density signals of these specific portions are ID1, ID2, and ID3.
Suppose that Then, the reference density signal of the color batch designated as the desired finishing color for the specific portion 11 is ODl, and the reference density signal of the color batch designated as the desired finishing color for the specific portions 2 and I3 is ○D2 and OD3. If there is, the reference gradation conversion curve Q is changed to the highlight point H1.
Coordinate points (ID1.ODt), (I
Dz, 0D2) and (ID3, OD3) to form a modified gradation conversion curve Q'.

The data of the modified gradation conversion curve q' obtained as described above is set as the gradation conversion table 7a of the image processing circuit 7. Therefore, when the color original 2 is scanned over the entire surface to obtain an output image, each inclusion level Jm degree signal IY, IM, and IC is converted into the gradation conversion table 7a for each color set as described above. When the ti tone processing is performed in accordance with the above, for each specific portion 11, I2, I3, each color output density signal carrying each color density of the specific color batch is output, and these specific portions 11, I2, I3
will now be finished in the same color tone as the specific color batch you referenced.

As mentioned above, the corrected gradation conversion curve q' is shown in FIG.
．． 0D2), (ID3, OD3), but even if it is corrected to pass as close to these coordinate points as possible, the color tone of the specific color batch that referenced the specific part on the final output image You can achieve the effect of finishing as close as possible to .

As mentioned above, the standard gradation conversion curve Q is modified to the gradation conversion curve Q.
' can be corrected by using a known interpolation smoothing process (for example, Japanese Patent Application No. 58-122164, No. 58-58).
Discrete data may be smoothed using a method such as that disclosed in Japanese Patent No. 145,490, and interpolation processing such as Lagrange interpolation, quasi-Hermite interpolation, B-spline interpolation, etc. may be performed on the smoothed data.

In this color image input/output system, the image processing circuit 7 performs color correction as well as gradation processing, and the parameter input section 15
Standard color correction coefficient data P input from
6 is set in the color correction table 7b in the image processing circuit 7.

Figures 5 and 6 show a color image input/output system to which the second embodiment method of the present invention is applied. Elements that are equivalent to the elements in are given the same number,
(I will not explain them again).

In this system, two color originals are scanned before the main scan.
The input density signals of each color @IY, IM, and IC over the entire surface of the document obtained by rough scanning are taken into the image signal input section 20, and from the image signal input section 2°, the above-mentioned input density signals of each color @IY, IM, and IC are sent to the calculation section 16. ,■M,IC is input. Arithmetic unit 1
6 is a rough scan data processing unit 21 which obtains the highlight and shadow densities of each color and the reference gradation conversion curve of each color from the input density signal IY1 rM and IC of each color, and outputs the highlight and shadow density signal P1 of each color and the reference gradation of each color. The conversion curve data P2 is input to the curve correction calculation circuit 78. Note that the reference gradation conversion curves for each color mentioned above are, for example,
As shown in Japanese Patent No. 8-145491, the cumulative density histogram of the color original 2 can be calculated from the input density signals IY, IM, and IC of each color.

Further, each color input density signal P3 of the specific portion is each color input density signal IY from the image signal input section 20.

IMiC is sent to the specific partial signal extraction section 22 in the calculation section 16, and the coordinate signal of a desired specific portion is inputted to the specific partial signal extraction section 22 by the coordinate input means 23, and the above Each color input density signal IY
, IM, and IC.

Each color highlight and shadow density signal P1 obtained as described above, each color reference gradation conversion curve data P2,
Each color input density signal P3 of the specific portion and each color output density signal P5 obtained in the same manner as in the first embodiment described above are input to the curve correction calculation circuit 18, and the following is the first
The gradation conversion table 7a is automatically set in the same manner as in the embodiment.

As an example of color patches, we have explained those summarized in "skin color chart", "gray chart", etc., but as shown in FIG. A color process chart 60°61... consisting of .402... may be used. However, charts that compile color batches for each main hue, such as the above-mentioned "skin tone chart" or "gray chart," are easy to use and can be used selectively according to the purpose, so you can create or purchase only the ones you need. Good and economical.

Both of the two embodiments described above are applied to a color image input/output system that directly outputs a final output image, but the method of the present invention is applicable to a color plate making system that creates a three-color or four-color halftone plate. is also applicable. In this case, the density of each color of the color batch may be defined by the dot area ratio, and each color reference brightness signal may carry the dot area ratio of each color. When a black plate is created in addition to the Y, M, and 0 plates, the black halftone area ratio is defined in the color batch, and the black signal is also determined for each color (Y, M,
C) Processing similar to signal processing may be performed.

(Effects of the Invention) As explained in detail above, according to the method for automatically setting gradation processing conditions of the present invention, gradation processing conditions can be set to 15- tones of the referenced color batch without the need for troublesome operations. Since the settings are automatically made, even an unskilled person can easily and quickly finish a desired portion of the final output image in a desired color tone without individual differences.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a color image input/output system to which the first embodiment method of the present invention is applied, FIG. 2 is a schematic diagram showing an example of a color batch used in the present invention, and FIG. 4 is an explanatory diagram illustrating the modification of the reference gradation conversion curve according to the present invention. FIG. 6 is a schematic diagram illustrating the flow of signals in the calculation section of the color image input/output system of FIG. 5, and FIG. 7 is a block diagram showing a color image input/output system to which the above method is applied. FIG. 3 is a schematic diagram showing another example of a color batch. 2... Color original 3... Input optical head 16- 4... Photoelectric converter 7... Image processing circuit 7a...
Gradation conversion table 10... Exposure light source 11... Modulator 12... Exposure head 14... Film 15... Parameter input section 16... Calculation section 17.
. . . Reference density table 18 . . . Curve correction calculation circuit 20 . . . Image signal input unit 21 . . Rough scan data processing unit 22 . 103.201.202.203.
301.302.401.402...Color batch IY, IM, IC...Each color input density signal OY10M1
QC... Output density signal for each color P2... Data for each color reference gradation conversion curve P3... Input density signal for each color in a specific portion P4... Color batch number signal P5... Reference depth signal Q for each color ...Standard gradation conversion curve Q'...Modified gradation conversion curve (voluntary) procedure...Director General of the Patent Office, May 1681, Case 3, Automatic setting method of display gradation processing conditions. Relationship with the person making the amendment Patent applicant Location 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name Fuji Photo Film Co., Ltd. 4, Agent 5-2-1-5 Roppongi, Minato-ku, Tokyo Date of amendment order None 6. Number of inventions increased by amendment None 8. Contents of amendment 1) The scope of claims will be amended as shown in the attached sheet. 2) On page 6, line 4 of the specification, "output density signal" is corrected to "output signal." 3) Insert "1 or halftone area ratio after ll1J of each color" in lines 5 and 7 for the same page. 3゜4) Insert "reference density signal" in lines 8.14 and 18 for the same page as "reference output signal". correct. -2. Claims Input density signals for each color from an image input device that separates and reads a color original into an image processing circuit, and performs gradation processing on these signals based on gradation processing conditions for each color. In a color image input/output system that inputs each color output signal after gradation processing to an image output device, a plurality of color patches are created by changing the density or halftone area ratio of each color, and each color in these color patches is Each color input density signal of a specific part of the document is stored in a storage means in association with an input code specific to the density or color batch, and the color tone of a specific part of the document is desired to be finished in the final output image with the same color tone as that of the specific color patch. inputting each color reference power signal of the specific color patch read from the storage means according to the input code designation of the specific color patch and data of a predetermined reference gradation conversion curve of each color to the calculation means; The calculation means calculates and corrects each color reference gradation conversion curve so as to indicate a value near the each color reference output signal for each color input density signal of the specific portion, and the data of the corrected gradation conversion curve after this correction. A method for automatically setting gradation processing conditions, characterized in that the gradation processing conditions are transferred to the image processing circuit and set as the gradation processing conditions.

Claims (1)

[Claims] Input density signals for each color from an image input device that separates and reads a color original are input to an image processing circuit, and gradation processing is performed on these signals based on gradation processing conditions for each color. In a color image input/output system that inputs each color output density signal after this gradation processing to an image output device, a plurality of color batches are created by changing the density of each color, and a plurality of color batches are created corresponding to the density of each color in these color batches. Each color reference density signal is stored in a storage means in correspondence with an input code unique to each color batch, and each color input density of a specific part of the document is desired to have a color tone similar to that of the specific color batch on the final output image. inputting the signal, each color reference density signal of the specific color batch read from the storage means according to the input code designation of the specific color batch, and data of a predetermined reference gradation conversion curve of each color to the calculation means. , -1-,,^r The calculation means calculates and corrects each color reference gradation conversion curve so that it indicates a value near each color output density signal with respect to each color input density signal of the specific portion, and this correction A method for automatically setting gradation processing conditions, characterized in that data of a subsequent modified gradation conversion curve is transferred to the image processing circuit and set as the gradation processing conditions. 2-