JPH01292329A - Copy exposure quantity control method for color document - Google Patents

Abstract

PURPOSE:To obtain a proper reproduced image without reference to the mount state of the document by measuring the light of formation, and selecting a low-level and a high-level light measured value range according to light measured values in a light measurement area and determining an image area or background area. CONSTITUTION:The minimum density value Dmin and maximum density value Dmax in the light measurement area (e.g. area matching with the largest area in a document to be copied) of the color document are determined. Then light measured density limit values (Dmin+alpha) and (Dmax-beta) which can be regarded as extremely low and high levels are stored in a light measuring means. Here, alpha is a density value and about 0.01-0.20 and beta is about 0.05-0.50. Then an area having picture elements where the light measured density value di of each small part (picture element) of the document which is read by utilizing a light measuring means is Dmin+alpha<=Di<=Dmax-beta is determined as an image area and other areas are determined as a background area prior to a copying process. An area density value regarding one of both areas is found and used as one arithmetic element to determine the best copy exposure quality, thereby performing control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applicable to color photocopying devices such as silver-salt photographic color copying devices (optical printers), electrophotographic color copying devices, laser color copying devices, etc. The present invention relates to an improvement in a color original copying exposure control method suitable for application to an image copying apparatus.

[Prior Art] When looking at a manuscript to be copied from the viewpoint of its composition,
It can be roughly divided into an image area and a background area, but when trying to copy a manuscript, it is important to reproduce the color and density in the image area as close to the original as possible. It becomes a problem. Therefore, attempts have been made to effectively solve this problem.

For example, as disclosed in Japanese Unexamined Patent Publication No. 60-22135, a document classification is determined in advance based on the contrast between the background of the document and the character pattern, and the document to be copied is applied to one of the document classifications. Methods for reproducing images, JP-A-60-112068 or JP-A-58-
As disclosed in Publication No. 184160, etc., copying exposure using the minimum density in the original, or the maximum density, minimum density, and intermediate value in the original is used to create images as close to the original as possible. Furthermore, as disclosed in Japanese Unexamined Patent Publication No. 59-15264, etc., the composition of a document is classified based on the maximum density and minimum density that appear at a predetermined frequency or higher in the density histogram. However, there are known methods for reproducing images by applying them to this document classification.

[Problems to be Solved by the Invention] However, these image reproduction methods reproduce original images that become two-tone images (B/W images) when copied, such as originals with black and white patterns or text originals. Although it is effective in some cases, it is not always effective when reproducing multi-tone images such as color originals, where the image itself has a complex tone distribution and the density difference between each tone is small. It was difficult to say that it was an effective method.

Therefore, for example, in the conventional method of reproducing images using information on the maximum density and minimum density of the original image, the maximum density and minimum density are only unique densities in the original image, and there are many intermediate density parts. The disadvantage is that the image cannot be properly reproduced, and it may even be more advantageous to simply control the copying exposure based on the density of the color image area.

On the other hand, in the conventional method that uses minimum density information, the size of the original to be copied is
If the size of the original (platen surface) or photometry range is smaller than the original, or if the original is not placed properly, the illumination light that passes through the original placing surface at a position outside the original may be There are cases where the light is reflected by the white surface of the holding plate and directly enters the photometric means, which has a drawback that it greatly affects the measured value of image density and significantly deteriorates the measurement accuracy.

Furthermore, with the conventional method that utilizes maximum density information, for example, when a thick book, which is a manuscript, is opened and placed face down on the document placement surface, and when copying is made in this state, the following A major drawback occurs.

In the case of thick wood manuscripts that have large dents on the outer periphery of the wood or in the center folds, in areas that should originally belong to the original document area, when copying, the document irradiation light will not be able to reach these dents. This is because the light passes through the area of the document placement surface corresponding to the image as it is, and in a part of the document area where it was originally assumed that there would be some reflected light, there will be an area where almost no reflected light will occur. It is. That is, if this phenomenon occurs,
The document density during photometry becomes a very large value, which causes a significant deterioration in measurement accuracy.

Such development is even more noticeable in three-dimensional objects such as packages and products.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel copying exposure amount control method for color originals that eliminates the various drawbacks of the conventional copying condition setting methods.

[Means for Solving Problem n] The configuration of the present invention to achieve this object is to measure the light of a color original before copying, and determine the appropriate copy at the time of copying from the obtained photometric value of the color original. In a color document copying exposure control method that determines the exposure amount, an image area or a snow scene area is determined by selecting a low level photometric value range and a high level photometric value range from the photometric values in the photometric area; The objective is to control the exposure amount for copying a color original based on the feature amount of the determined area.

Further, in the above, it is preferable that the copying exposure amount is determined based on the image reproduction characteristics and the reproduction density control characteristics based on the characteristic amount.

[Function] The effect of the present invention with this configuration is that in the copying exposure control method for color originals, when performing calculations to determine the appropriate density value during copying, extremely high level photometric density values obtained from the original surface and The present invention is arranged so that extremely low-level photometric density values are excluded from the calculation elements of the calculation for determining the appropriate density value.

[Example] The present invention will be explained below based on the illustrated embodiment, but prior to that, a detailed explanation of the present invention will be given.

In a color original with a typical composition, the amount of image information is naturally larger in the image area where the main image part is placed, and the difference in density between each small part (pixel) within that area is greater than that in the background area of the original. is larger than the concentration difference between each small part in .

Therefore, when photometry is normally performed between small parts of each area, the frequency of appearance of 4 degree difference (photometry between each small part of the image area) is within the range of a relatively high density difference level: it appears frequently, and the background The appearance frequency of the photometric density difference between each small portion of the area is that the photometric density difference frequently appears within the relatively low range of one novel density difference. Furthermore, since the sizes of extremely high density regions and extremely low density regions occupying a composition are not so large, the frequency of occurrence of extremely high photometric densities and the frequency of occurrence of extremely low photometric densities is usually low.

On the other hand, in a normal copying device, the size (area) of the document placement surface is made larger than that of the original to be copied, and the document holding plate provided behind the document placement surface is The holding surface is usually set to white.

Therefore, when a sheet-like color original is set on the document placement surface of such a copying device and photometrically scanned with a slit-shaped irradiation light, a portion of the irradiation light is placed on the document placement surface. The light passes through the document placement surface in the area where there is no document inside, and is reflected by the white holding surface of the document holding plate.
This causes the phenomenon that the light enters the photometric means.

Therefore, in copying where there are many areas where no original exists, the appearance frequency of each small portion in the area where no original exists in terms of photometric density will appear many times within the range of the lowest density level.

If this is expressed as a histogram for each photometric density in each small portion of the document, the shape will be as shown in FIG. 1, for example.

On the other hand, as mentioned in the "Problems to be Solved by the Invention" section, when a thick piece of wood that is a manuscript is opened and placed face down on the manuscript placement surface, and when copying is performed in this state, the manuscript area Since there are various depressions in the area that should belong to the image, the document irradiation light passes through the area of the document placement surface that corresponds to the depression, and most of the reflected light from there is incident on the photometry means. This causes the phenomenon of disappearing. Therefore, the photometric density related to the recessed portion becomes extremely high.

Therefore, in a manuscript that has many such concave parts,
The frequency of appearance of each small portion of the area corresponding to the concave portion in terms of photometric density is that many small portions appear within the range of the highest density level.

If this is expressed as a histogram for each photometric density in each small portion of the document, the shape will be as shown in FIG. 2, for example.

Also, in the case of three-dimensional objects, etc., a document holding plate may not be used.
A similar problem occurs because the original i is used in a state where it is floating far above the placement surface.

However, when trying to obtain a high-quality reproduced image of a color original, when performing calculations to determine the appropriate density value, it is necessary to use such an extremely high level of photometric density and/or extremely low level of photometric density. The existence of this becomes an extremely disadvantageous condition. Therefore, it is necessary to exclude this abnormal photometric density from the calculation elements of the calculation for determining the appropriate density value.

The present invention was made based on this idea.

Hereinafter, a method of controlling exposure amount for copying a color original according to the present invention will be explained with reference to FIGS. 1 to 3.

First, as a first step, the minimum density value Dmin and maximum density value Dmax in the photometric region are determined, which are the basis of calculation for determining an appropriate density value.

In this case, the photometry area may be set, for example, as an area that matches the largest size of the color originals that are planned to be copied, or as an area that matches the scanning length during photometry. good. For example, let it be the width of the document placement surface of a copying machine.

Further, as the above-mentioned minimum density value Dmin, in addition to the actual photometric value, for example, the density value of white color used on the holding surface of the document holding plate of the copying apparatus may be used. In addition to the actual photometric value, the maximum density value D max may be set to a predetermined value as a density value for black, for example.
Alternatively, the photometric density value when both the original and the original holding plate are not present on the original placing surface may be used.

As a second step, the extremely low-level photometric density range that can be considered as an abnormal photometric density is determined by, for example, the range of α in FIGS. 1 and 2 Dmin ~ (Dmin + a
), and the extremely high level photometric density range considered as abnormal photometric density is set, for example, as the range β (Dmax-β) to Dwax in both figures. The conditions for the photometric density limit values (Dmin+a) and (DIIIax-β) that can be considered as abnormalities are stored in an appropriate photometric means as one of the calculation elements when performing calculations to determine the appropriate density value. or in a storage means in the appropriate concentration value determination calculation means, and finally set in the calculation means. As the photometric means and appropriate density value determination calculation means used in this case, means of various configurations that are known per se can be used.

Note that α is a density value of approximately 0.01 to 0.20, and β is approximately 0.05 to 0.50.

α may be set to include the density of the platen, or may be set to include the white background of a normal original.

Further, β may be determined depending on the accuracy of the photometric sensor, or may be determined based on the maximum density of 1.5 to 2.0 in normal reflective development.

Further, α and β are within a predetermined concentration range, for example, α<0.20,
When β<0.50, the frequency on the histogram is 0, or the lowest class density value (DI in Figures 1 and 2,
Do) may be detected and set as an image area.

Although various other methods can be considered using histograms, the present invention is included in methods related to extraction using histograms of image regions.

The present invention also includes a method based on a concentration cumulative distribution curve as long as it is based on a similar principle to the method using a histogram.

As a third step, the photometric density value (DI) of each small portion of the original read using an appropriate photometric means during photometric scanning of the original surface prior to the color original copying process is calculated using the two methods described above. Photometric density range Dmin+a≦1) 1<DInax
A comparison is made to see if it is a value other than -β, and pixels with photometric density values within these ranges are extracted (selected) as an image area. As the extraction (selection) means used in this case, the pixels having various configurations which are known per se are used, and the pixels satisfying Collenyoryl DIIlin+α≦D1≦D max−β are selected.

Note that, unlike the above, each step described above may be processed using reflectance or a value corresponding to the reflectance as the photometric value instead of the photometric density value.

In addition, the minimum density value Dmin and the maximum density value D m
Regarding ax, it is possible to use a photometric means to measure the light during photometric scanning of the document surface, or two photometric density values Da
A value corresponding to +in%D max may be stored in advance.

Further, the maximum photometric density value D max may be determined as Dl=γ (for example, density of γ=2.0) when Dl>γ.

In addition, the photometric density limit value (Dm
in +a ), (Dmax-β) as the standard 3
It is also possible to determine the area by setting each color, for example, red, green, and blue light, and extracting each photometric light based on these three photometric density ranges.

In addition, the density value when no original is set on the original g4 placement surface (density value of the white original holding surface) can be stored in advance, or the extreme edge of the original placement surface can be photometered during photometry scanning. , these values may be taken as δ values, and in the case of D,=δ, these values may be excluded from the calculation elements. In this case, it is preferable to have a concentration that corresponds to the δ value.

As the fourth step, the predetermined concentration range Dmin+α≦D
, ≦D max-β (each small part of the document) is selected, the image area and background area are determined, with the area containing this pixel as the image area and the other area as the background area. Ru.

Note that the background area in the present invention may include not only the white background of the platen but also the white background of the document, so the non-image area of the image is used as the background area.

In the subsequent fifth step, feature balls of the image region and/or background region are calculated.

That is, among the image area or background area obtained by the step of determining the image area density described in the previous step,
The area density value relating to either one of them is determined, and this is used as one calculation element when determining the optimum copying exposure amount to determine and control the optimum copying exposure amount for a color original.

Alternatively, it can be classified into regions, D mi
The area density may be determined directly from n+α<DI<Dmax-β.

For example, the average value of Di, the most frequent concentration of the concentration histogram, etc. can be used.

Image areas are divided into main image areas with large color density differences between different areas and other image areas with small color density differences, and each area is exposed first! Computational elements for determination may also be found.

In determining this optimal copying exposure amount, a control means 50 (see FIGS. 4 and 6) is used, which controls the determination of copying conditions and exposure control amount during original copying.

This control means 50 includes, in addition to general means such as arithmetic means, storage means, and output means, which are included in a normal control means, a means for setting a photosensitive characteristic value of a photosensitive material, a means for extracting an area of a copying object, Various means (none of which are shown) related to the present invention are provided, typified by feature value setting means for image areas and the like.

In this case, the photosensitive characteristic value setting means is configured to be able to set the photosensitive characteristic value to be used at the time of copying in the calculation means, for example, by manual operation or automatic reading operation using a bar code. In the case where the material is prepared, the configuration is such that a specific photosensitive characteristic value can be selected from among the respective photosensitive characteristic values, for example, by manual operation or automatic reading operation.

On the other hand, when actually copying a color original, the area extracting means separates and extracts two areas, an image area and a background area, using the above-described image area or background area determination method. Then, the concentration f' i (dji) of one of the regions is determined.

After preparing the control means 50 having such a configuration, the method for determining the optimum copying exposure amount is carried out, for example, as shown in FIG.

(1) First, the photosensitive characteristic value of the photosensitive material at the time of use is selected and set in the control means 50.

(2) Next, in the apparatus shown in FIG. 4, a predetermined test chart 11 prepared in advance is placed on the document placement surface 10, which has a reference plate 13 on a part of the lower surface. , the chart surface is photometrically scanned with slit-shaped illumination light.

Then, the light reflected from the reference plate 13 and the test chart 11 is photometered by the photometer 33, and the photometric information value of the three color component light related to the reference plate 13 and the photometric information of the three color component light related to the test chart 11 are obtained. The concentration value of the test chart 11 is obtained by introducing the value into the calculation means. is determined and the value is stored in the storage means mentioned above.

(3) Next, copy the test chart 11 to complete the color copy, set this color copy on the original g4 mounting surface 1o instead of the test chart 11, and perform photometric scanning of the color copy surface. conduct.

The photometric procedure in this case is the same as the procedure for photometric scanning of the test chart 11 itself, so a detailed description thereof will be omitted, but the density of the color copy of the test chart 11 obtained by this photometric scanning is The value D0 is stored in the storage means described above.

Note that each photometric information value obtained in these two photometric scans may be an actual photometric density value or its corresponding value; however, in this case, the corresponding value may include, for example, photometric A logarithmic conversion value of the density value, a function equation corresponding to the brightness of the document, or an appropriate value obtained from a conversion table is used.

(4) Furthermore, test chart 11 obtained in the above (2)
The density value D0 of the color copy and the density value De of the color copy of the test chart 11 obtained in the same <(3) section are arranged on the horizontal and vertical axes of the graph, respectively, to create an original as shown in FIG. Create a graph representing density versus copy density.

Then, from this graph, the image density reproduction characteristic (A) having the image reproduction curve at each time when copying the original is determined and stored in the storage means. This image reproduction characteristic (A) can be represented by the density value of any one of the three colors, but it may also be created for each color. - Illustrations, etc.) and the type of photosensitive material used as the copying material (soft/hard contrast, reflective/transmissive, negative/positive, etc.). Note that this characteristic (A) may be a table value or a functional expression. Furthermore, this characteristic (A) may be set in advance. In this case steps (1) to (4)
is not necessary, and the setting values can be stored in memory as table values or function expressions. Alternatively, the information may be inputted externally manually or using a storage medium such as an IC card, so that the information can be input when changing the characteristics of the copying material.

(5) On the other hand, in parallel with the creation of this image reproduction characteristic (A), the reproduction density control characteristic (B) shown in FIG. 8 is determined and stored in the storage means. This reproducible density control characteristic (B) is
For example, De=K, xD0+K of the two density values Do and DC mentioned above.

(However, K and Kb are each constant, for example, K
, = 1.0, K, = O, O). In this case, Ka corresponds to γ. In addition, as another method of obtaining, for example, De may be obtained as a linear or nonlinear functional expression of Do, or,
It can also be obtained as a table value. Preferably, as in the case of the image reproduction characteristic (A) described above, a plurality of them are created depending on the type of original or photosensitive material.

In addition, when setting this reproducible density control characteristic (B), it may be set arbitrarily in advance or may be set manually.
Furthermore, in the case where a plurality of reproduction density control characteristics (B) are created, the selection can be made manually or automatically. Furthermore, it is also possible to create a kind of broken line with different slopes depending on the low density area, medium density area, and high density area.

(6) Now, in this method of determining the optimum copying exposure amount, Do
+= f + (C++) or s Dot = f + (di+) + g
The optimum exposure amount, which is a copying condition, is determined using the relational expression +(VJI).

In this formula, Dot represents the exposure control density that determines the optimum exposure or its corresponding value, and the contents of each variable and symbol used in the formula are as follows.

The original density value f r (dJI) is a density value or corresponding value that characterizes the density of the image area, and is a value determined using the above-mentioned image reproduction characteristics (A) and reproduction density control characteristics (B). It is. For convenience, fl(dJI) is f I
(June).

The correction value 8 (vjI) is a correction value for the f + (dJI), and is determined from a value related to the image estimated to be the main image portion or a value depending on a specific image or a specific original. It is something.

The symbol dJI is a value indicating at least one density value or a corresponding value among the average density, maximum density, minimum density, density determined based on a histogram in the aforementioned image area.

The symbol V indicates the reference element of the value related to the image that is estimated to be the main image part. weighted average concentration.

■Characteristic values of the central area of the document or areas other than the peripheral areas of the document (for example, density, area, color, composition ratio, etc.).

■Average density of specific areas such as skin color.

■Characteristics of high saturation area and neutral color area (e.g. density, area,
color, etc.).

Density of color/density level with high 0 area ratio.

■ Maximum concentration and/or minimum concentration or a constant concentration level value including them.

■Characteristic values or features of the main image part and the specified area.

(2) Even when the image is divided into multiple image areas, the above (2) to (4) apply, and the average or selected value of multiple areas is used.

■Density value calculated from the average density or histogram of areas where the density difference between adjacent photometric areas is greater than a predetermined value.

Further, the symbol VJI may be a value depending on a specific image or document (for example, the area of a high-precision region, etc.). Symbol VJ
In addition to the value related to the main image part, I is a value for a specific image (for example, an image with high precision or a large area of neutral color) or a specific document f.
1 (for example, a document that is difficult to copy properly) may be a correction diagram. It represents a value using at least one element among various elements such as.

Symbols i and j are one of R, G, B or R, G,
Symbol indicating that B is common and characteristic value No.
It is a symbol representing.

The specific structure of a silver halide photographic color copying apparatus that implements this method of determining the optimum copying exposure will be explained with reference to FIGS. 4 and 5.

In FIG. 4, numeral 10 is a transparent document placement surface provided in a silver-halide photographic color copying device, and its size (area) is as follows:
It is made larger than the test chart 11 or color original to be copied. Then, a predetermined test chart 11 or a color original is set on that surface, and a document holding plate 12 having a white holding surface is provided to hold the original. 13 is an achromatic reference plate (for example, white, gray, etc.);
It is provided at the lower left end portion outside the document placement area of 0.

Reference numeral 14 denotes a light source unit that reciprocates at a predetermined scanning speed along the document placement surface 10, and inside thereof there is provided a suitable rod-shaped light source 15, a flapper 16, and the document placement surface 10.
a mirror 17 inclined at 45 degrees with respect to the light source 1;
The test chart 11 or the color original placed on the lower surface of the reference plate 13 and the original placing surface 10 can be scanned by the slit-shaped irradiation light from 5 on both the forward and backward paths.

18 is the first one in conjunction with the reciprocating scanning of the light source unit 14.
A mirror unit that reciprocates in the same direction in parallel at a speed of 20 is configured so that light (incident light from the original unit 14) can be returned in parallel and guided to a lens unit 22, which will be described later.

Reference numeral 22 denotes a lens unit incorporating a single-copying optical system consisting of a front group lens 23 and a rear group lens 24. For example, when converting the copying magnification, the light source unit 14 and the mirror unit 18
The lens is configured to be movable in the front and rear directions on its main optical axis so as to correct a focal shift caused by a magnification conversion operation due to relative adjustment.

Y-M-C are yellow filter, magenta filter, and cyan filter, respectively, and each of these filters Y-M-
C is arranged so as to be movable in a direction perpendicular to the main optical axis at a position near the principal point between the two lens groups 23 and 24, and is moved along the main optical axis by driving force from drive units 131 to 133, which will be described later. It is configured to be able to change the amount of each insertion into the optical path. Then, by changing the amount of insertion of these filters, the pre-purchase of the reflected light from the Tess) chart 11 or the color original (hereinafter also simply referred to as the reflected light from the color original, etc.) can be adjusted, and the It is configured to be able to correct color balance. Note that it is also possible to add an ND filter or the like if necessary.

Reference numerals 25 and 26 denote two diaphragm plates arranged movably in opposite directions behind the rear group lens 24, and which use a driving force from a drive unit 134, which will be described later, to reduce the amount of light reflected from the color original, etc. The light amount can be adjusted.

Reference numerals 28 and 29 denote two fixed mirrors that are fixedly provided in the main optical axis optical path, and reflect light from a color original or the like that has passed through the lens unit 22 to a photometry means 33, which will be described later.
and take a relative arrangement that can lead to the slit exposure position E.

Reference numeral 31 denotes an optical path switching mirror for dividing the main optical axis optical path into a photometric optical path and a copying optical path, and is provided so as to be tiltable about a shaft 30 at a position in front of a photometric means 33, which will be described later. Reference numeral 32 denotes a condensing mirror that is removably installed in the reflected optical path of the fixed mirrors 28 and 29, and as shown in FIG. It is configured as an aggregate structure of mirror pieces 32a.

The condensing mirror 32 and the optical path switching mirror 3
1 means that in the normal copy mode, both of them are located at the solid line position (copy state position), so that the fixed mirror 2
The relative arrangement is such that the reflected light from the color original, etc. that has passed through the 8. Interlockingly, optical path changing mirror 3
1 rotates to the retracted position shown by the dotted line, and the condensing mirror 32 is conversely displaced to the optical path insertion position shown by the dotted line, so that the reflected light from a color document, etc. is photometered via the condensing mirror 32. Relative arrangement that allows the light to enter the means 33 (photometering state position)
is configured to automatically switch to

33 is a photometric means installed in the photometric optical path, which includes a red sensor 33a, a green sensor 33b, and a blue sensor 3.
It has three built-in sensors 3c and is configured as a density reading means that can photometer the reflected light from the color document etc. as three color light components.

In the illustrated example, the density reading means is configured with three sensors, but this is a preferred embodiment, and if necessary, the density reading means may be configured to be represented by one color. You may.

Reference numeral 35 denotes a magazine in which a photosensitive material 36, which is a copying material, is wound into a roll and stored therein.In the illustrated example, only one magazine is provided, but as mentioned above, this magazine 35 can store multiple types of photosensitive materials. In the case of a silver salt photographic color copying apparatus that uses materials 36 according to their photosensitive characteristics, a plurality of photosensitive materials 36 are installed depending on the number of types of photosensitive materials 36.

In this case, an appropriate means is used so that the photosensitive material 36 to be used at each time can be selected and supplied to the slit exposure position.

A pair of pull-out rollers 37 and 38 are provided just before the magazine 35, and are used to pull out the photosensitive material 36 to be used from the magazine 35 when copying a color original or the like.
39 is a cutter for cutting the pulled out photosensitive material 36 into photosensitive material pieces 36a of a certain length.

40, 41 and 42, 43 are two pairs of rollers for transporting the photosensitive material piece 36a cut by the cutter 39 and stopping it at the slit exposure position E. When exposing a color document or the like, the light source unit 14 The exposed photosensitive material piece 36a rotates in synchronization with the scanning, and after the exposure is completed, the exposed photosensitive material piece 36a
It is configured to rotate again in order to transfer it to a processing section 44, which will be described later.

44 is a processing section that performs processing such as development, bleaching, fixing, washing, drying, etc. on the photosensitive material piece 36a after exposure, and an appropriate take-out tray ( (not shown).

Reference numeral 50 denotes a control means having the functions and configuration described above, and is expressed by the relational expression D. l= f + (, d J I)
+g l (VJI) Each drive unit 131 to 13, which will be described later, is
The drive amount of 4 can be controlled.

Reference numerals 131 to 134 are drive units that use, for example, appropriate pulse motors or solenoids, and as described above, each filter Y-M is controlled in accordance with the exposure amount control signal from the control means 50.
-C and the aperture plates 25 and 26.

This silver-halide photographic color copying device has a copying condition setting mode designation key that is operated when setting copying conditions, a copying mode designation key that is used when copying normal color originals, and an exposure start key (which (also not shown) are provided.

The operation of this silver salt photographic color copying apparatus will be explained below with reference to FIGS. 4, 6, and 7.

(11) First, operate the copying condition setting mode designation key to set the operating state of the silver halide photographic color copying apparatus to the copying condition setting mode. When this copying condition setting mode is set, each filter YM-C and diaphragm plates 25 and 26 are set to their standard positions, and furthermore, the optical path switching mirror 31 and the condensing mirror 32 are both indicated by dotted lines. The photometer 33 is positioned at the relative position (photometering state position), and is ready to allow reflected light from a color document or the like to enter the photometer 33.

In this state, place the test chart 11 on the document placement surface 1.
When the exposure start key is operated after the original is set on the document holding plate 12 as specified, the light source unit 14, mirror unit 18, and lens unit 22 move in the forward direction in synchronization. Then, a first photometric scan is performed on the reference plate 13 and the test chart 11.
By the scanning, the reference plate 13 and the test chart 11 are
The reflected light from the light source unit 14 and mirror unit 1
8, the lens unit 22, the fixed mirrors 28 and 29 in sequence, and is further focused by the focusing mirror 32, and then enters the photometry means 33.

(12) The reflected light from the reference plate 13 and the reflected light from the test chart 11, which entered the photometry means 33 in this way, are separated into three color component lights in time series by the respective sensors 33a to 33c. Here, photometric information values related to each reflected light are obtained.

Therefore, these photometric information values are calculated within the control means 50 to obtain the density value of the above-mentioned (2) regarding the test chart 11. and stores it in the storage means in the control means 50.

(13) When the light source unit 14 moves to the rightmost position of the document placement surface 10 and the first photometric scan is completed, the copying operation of the test chart 11 is subsequently started. In this case, prior to the start of the copying operation, the optical path switching mirror 31 and the condensing mirror 32 are both automatically displaced to the relative position (copying state position) indicated by the solid line position, and the color original, etc. The state is changed so that the reflected light from the slit reaches the slit exposure amount i7E.

Further, in this configuration, the photosensitive material 36 is
The photosensitive material piece 36a is pulled out from the magazine 35 by the cutter 39 and cut into a certain length by the cutter 39, and this photosensitive material piece 36a is further passed through two pairs of rollers 4.
0.41 and 42.43, and are set at the slit exposure position. That is, the state in which the test chart 11 can be copied is completed.

Therefore, the light source unit 14, etc. performs a return scan based on a predetermined sequence (although it is a copy scan, it is the second scan).
When the process starts, the photosensitive material piece 36a at the slit exposure position E moves in synchronization with this scanning, and slit exposure is performed.

Then, at the end of the slit exposure, the roller pairs 40 to 4
3 rotates again and sends this photosensitive material piece 36a to the processing section 44, where it is subjected to various processes such as development, bleaching, fixing, washing with water, and drying to complete the color copy of Test Char).11. .

(14) First return scan (second scan)
), both the optical path switching mirror 31 and the condensing mirror 32 return to the photometric state positions, and are ready to allow reflected light from a color document or the like to enter the photometric means 33.

Therefore, in this state, if you remove the test chart 11 from the document placement surface 10, set a color copy of the test chart 11 on the document placement surface 10 instead, and operate the exposure start key, the light source unit 14 etc. The second photometric scan (the third scan) is started, and the reflected light from the reference plate 13 and the color copy is made to enter the photometric means 33, as in the first photometric scan.

Therefore, as in the case of the first photometric scan, the photometric information values of the three color component lights related to these reflected lights are measured in time series, and by calculating these photometric information values, the test chart 11 is calculated. The density value De of the above item (3) related to color copying can be obtained.

(15) Now, the concentration value according to the test chart 11. The image reproduction characteristic (A) is created within the control means 50 by using both the density values D0 and De of the color copy of the test chart 11. Further, the reproduction density control characteristic (B) is obtained in advance in the control means 50. Although the copying condition setting operation has been completed through the operations up to this point, this setting operation is a regular operation that may be performed periodically, for example, at the beginning of each day.

(16) After completing this copy condition setting operation,
Place a color copy of this test chart 11 on the document placement surface 1.
A color original to be copied is set on the original placing surface 10 instead, and a third photometric scan is performed.

This third photometric scan is actually carried out as pre-scanning when copying a color original, but to simplify the explanation, it is simply an extension of the previous copying condition setting mode. I will explain.

In this photometric scanning, the above-mentioned photometric means 3, which is a reading means,
3 to measure the reflected light from the color original, and then calculate the density f+'(d
Find JI).

In this case, first, the image area or background area is extracted from the original density of the color original as described above.

Then, from this f+'(dJI), which determines the density f+'(dJI) of the image area, and the reproduction density control characteristic (B) in FIG. The density value f + that characterizes the image area using
Find (dJI).

That is, the copying exposure amount is determined from the image reproduction characteristic (A) so that the original density f (1) becomes the density C8.
Here, when the spectral sensitivity distribution of the photometric sensor exactly matches the spectral sensitivity distribution of the copying material, the photometric density=iog (exposure amount).

Next, the concentration value f + (dJI) is adjusted to match the above relational expression D0 = f1 (dJI) + (dJI). The optimum exposure amount, which is the intended copying condition, is determined by adding the value of gI (vjI) determined in relation to the image estimated to be the main image portion, the specific image, or the document.

(17) Then, the exposure amount control density value Dot that determines this optimum exposure amount is set for each drive unit 131 to 133.
through each filter Y-M- which is placed in the standard state
C, and/or the two aperture plates 25 and 26, and in order to realize this DO'l, each of these filters Y-
MC and/or the aperture plates 25 and 26 are driven.
Therefore, the insertion amount of each filter YM-C into the main optical axis optical path and/or the aperture amount of the two diaphragm plates 25 and 26 change according to the optimum exposure amount.

In addition, the exposure amount control density value Dot that determines this optimum exposure amount
It is also possible to configure the system so that the optimum exposure amount can be achieved by, for example, controlling the amount of illumination of the document and the scanning speed.

(18) After the third photometric scan is completed, the light source units 14, etc. are configured to return to their initial positions, so after the light source units 14, etc. return to their initial positions, press the copy mode designation key. Operate to shift the state of the silver salt photographic color copying apparatus to copy mode.

In this mode, in the salt photographic color copying apparatus, on the one hand, the optical path switching mirror 31 and the condensing mirror 32 are located at the solid line position, and the reflected light from the color original can be imaged at the slit exposure position. On the other hand, the photosensitive material 36 is pulled out from the magazine 35, and the photosensitive material piece 36a is placed in a position where it can move in synchronization with the copy scanning of the light source unit 14, that is, slit exposure is performed on the photosensitive material piece 36a. You will be in a state where you can get it.

Therefore, if you operate the exposure start key with the color original still set on the original placement surface 10, you can basically use the same copying procedure as in the case of copying the test chart 11 described above. Exposure is started for the material piece 36a. However, in this case, the amount of insertion of each of the filters Y and M-C into the main optical axis optical path and/or the aperture amount of the two diaphragm plates 25 and 26 have already determined the appropriate exposure amount. As a result, copies of color originals that have been reproduced can be completed as color copies with high fidelity and reproducibility that could not be obtained using conventional methods.

Up to now, we have described one aspect of the present invention that aims to faithfully reproduce image density, but the present invention is not limited to this, and it is also possible to utilize reproduction density control characteristics according to the user's preference etc. It is.

In this case, a reproduction density control characteristic is created by changing the γ value to 1, etc., but considering the user's preference etc.
It is preferable to create a plurality of the above-mentioned reproducible density control characteristics and, for example, provide manual or automatic selection means so that they can be appropriately selected and used. Further, in this example, the reproduction density control characteristic may be configured to be changed depending on the image content of the document.

Further, it is preferable that the above-mentioned document density value f+'(dJI) is determined as a function of the image feature amount. For example, f+'(dJI)='Katd+Kb+dzi
+ K C1d31+ φ・φ However, dll; (Σdh)/k... Average density of the image area d2□; dmax... Maximum density of the image area a31
; dmin...Minimum density of the image area Kal, Kbl,
Calculated as a coefficient including KclO. In addition, the above-mentioned relational expression D oI
= f + (dJI) + g + (VJI), F
+ = (dJI, VJI).

However, F in this case is f+'(dt+) in the previous example.
From the value of Fl “(d) + , VJI ) corresponding to
It is assumed that the image density reproduction characteristic (A) and the reproduction density control characteristic (B) are used.

These are D' o+= f +'(dJI) + g
>'(VJI), the DOI may be obtained using the characteristics (A) and (B).

The amount f'(d''+) may be used in the relationship f+'(d''+)-Δd. Also, as shown in Figure 8, △C-
The exposure correction amount that corrects the reproduced density by ΔC from C+-Co may be determined.

In addition, even if the image reproduction time characteristics (A) and reproduction density control characteristics (B) are created using the photometric information values stored in advance, the time when the test chart 11 and its color copy original image are read. Alternatively, the difference between the image reproduction characteristic (A) and the reproduction density control characteristic (B) can be directly stored and controlled. Furthermore, Dot does not necessarily have to be determined by the procedure shown in Fig. 8, and Fig. 8 shows the characteristics (A), (B).
) is just one example of a determination method based on

Then, image reproduction characteristics (A) and reproduction density control characteristics (B)
In the case where the images are prepared for each type of copying material, it is convenient to install a manual or automatic selection means that can select the copying material and the image reproduction characteristics at the same time.

In addition, the method of using each characteristic value should be selected appropriately depending on the purpose of use, such as whether to faithfully reproduce image density or to suit the user's preference. Good.

Further, in the illustrated example, the photometric scanning of the test chart and the copying scanning of the test chart are performed in a VF series, but they can also be configured to be performed simultaneously (in parallel). In this case, for example, instead of the optical path switching mirror '31, a half mirror (beam splitter) that reflects part of the light and transmits the other part of the light may be fixed in front of the photometry means 33 to separate the photometry optical path and the copying optical path. are configured so that they always exist at the same time.

Further, in the illustrated embodiment, a test chart is used for determining the copying conditions, but for example, each filter Y-M-
By inserting C or ND filters in various shapes into the main optical axis optical path, it is also possible to create a pseudo reference original image in place of the test chart and use it to determine the copying conditions. be.

On the other hand, when looking at the color image copying method of the present invention from the perspective of the apparatus to which it can be applied, the apparatus to be implemented is as follows:
The present invention is not limited to the illustrated example, and may be, for example, an electrophotographic color copying machine, a thermal transfer color copying machine, an inkjet color copying machine, a laser color copying machine, or a video color copying machine.

Although one embodiment has been described above, it should be noted that the color image copying method of the present invention is not limited to this, and can be implemented with various modifications without changing the gist thereof. .

[Effects of the Invention] According to the present invention, it is possible to obtain an appropriate reproduced image of a multi-tone color original on any original placement surface.

[Brief explanation of the drawing]

Figure 1 shows the histogram of each photometric density in each small part of the original when a sheet-like color original whose size is smaller than the photometric value range is scanned with slit-shaped illumination light. FIG. 3 shows a histogram for each photometric density in each small portion of the document, which is generated when a document with many concave portions is scanned with slit-shaped irradiation light. It is a block diagram showing each step for realization. 4 to 8 are diagrams for explaining a method for determining the optimum copying exposure amount used in implementing the color image copying method of the present invention, and FIG. 4 shows the method for determining the optimum copying exposure amount. A schematic configuration diagram of an example of application to a silver halide photographic color copying device, FIG. S is a cross-sectional view showing the structure of a condensing mirror, and FIG. FIG. 7 is a block diagram for explaining the method, FIG. 7 is a flowchart for explaining the flow for obtaining the appropriate exposure amount, and FIG. 8 is a graph showing the relationship between original density and copy density used in determining the exposure amount. . Explanation of symbols 10... Original placement surface, 11... Test chart, 12... Original holding plate, 13... Reference plate,
14...Light a-Z,=tsu)-118...Mirror unit, 22...Shinzu unit, 25, 26...
Diaphragm plate, Y...yellow filter, M...magenta filter, C...cyan filter, 31...optical path switching mirror, 32...condensing mirror, 33...photometering means, 3
6... Photosensitive material, 36a... Photosensitive material piece,
37, 38, 40-43... Roller pair, 39... Cutter, 44... Processing section, 50... Control means, 131-134... Drive section, E... Slit exposure position FIG , 2 Dmin
u [noxFIG, 3 FIG, 5 FIG, G 25.26 FI G, 7 FIG, 8 △d Procedure Nefusho (spontaneous) June 27, 1985 1, Indication of the case 1988 Patent Application No. No. 122762 Address 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name (
520) Fuji Photo Film Co., Ltd. 4, Agent 10
1 3864-4498 Address: 4th Floor, 5th Floor, Chiyoda Iwamoto Building, 3-2-2 Iwamoto-cho, Chiyoda-ku, Tokyo, "Detailed Description of the Invention" section of the specification to be amended, Drawing 6, Contents of the amendment (1) The description in the "Detailed Description of the Invention" column of the specification is amended as follows. 1) Insert a new line after "coefficients to include" in the first line of page 41, and insert [K; number of photometric density values: photometric density value No., J]. (2) Correct Figure 8 as shown in the attached drawing.

Claims (2)

[Claims] (1) In a color original copying exposure control method in which the color original is photometered prior to copying and the appropriate copying exposure during copying is determined from the obtained photometric value of the color original, photometry within the photometry area is used. A color function that selects a low-level photometric value range and a high-level photometric value range from the values to determine the image area or background area, and controls the exposure amount for copying a color original based on the feature amount of this determined area. A method for controlling the exposure amount for copying originals. (2) The copying exposure amount control method for color originals according to claim 1, wherein the copying exposure amount is determined from image reproduction characteristics and reproduction density control characteristics based on the feature amount.