JP2515382B2 - Exposure amount determination method for image copying apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of determining an exposure amount of an image copying apparatus, and more particularly to an automatic photo printing apparatus (automatic printer for printing an image from a color photograph such as a color film onto a color paper). ) The method for determining the exposure amount for photographic printing for determining the exposure amount.

[Problems to be Solved by Prior Art and Invention]

A color negative transmits B, G, and R3 color lights as a whole screen, but it is empirically known that the transmission ratios of these three color components are generally substantially equal or constant.
Therefore, in the automatic printer, the printing light amount (exposure amount) is determined based on the following formula.

logFj = Kj + Dj (1) where logF is the logarithm of the amount of printing light, K is a constant, D is the integrated negative transmission density (LATD) measured by the photometric system, and j is B,
The color light is either G or R.

However, if the amount of printing light is controlled by the automatic printer based on the above formula (1), the print from the under-exposed negative has a higher overall density than the print from the proper negative, and the print from the over-exposed negative has a higher density. Will be lower. For this reason, a slope control circuit is provided to
The exposure amount is determined by correcting Dj. on the other hand,
Even in automatic printers equipped with a slope control circuit as described above, negatives that have changed significantly over time, negatives (different types of light source negatives) taken with light sources (fluorescent lamps, tungsten lamps, etc.) that are significantly different from daylight, and color areas With a negative or the like having a defect, defective print with an incorrect color balance is likely to occur. Further, film manufacturers (films of different types) having different sensitivities (different film types) have different sensitivities, densities, etc. of the three photosensitive layers, so that good prints cannot be produced under the same printing conditions. Therefore, print conditions are determined by trial and error for each film type and stored in memory, and the print conditions are selected for each film type to create a print. For this reason, Dj in the equation (1) is corrected (color correction), and the exposure amount is determined by changing the slope control circuit value in a different type film.

As a method of determining the exposure dose for improving the above problems,
Conventionally, there is known a method in which a screen of a color photographic original image is divided into a large number of pieces and photometric data obtained by photometry is evaluated, and the photometric data is selected and used for exposure control. These methods include the first method in which each photometric data is compared with a reference value and the printing exposure amount is determined only by the photometric data selected based on the comparison result, and the printing exposure amount in consideration of all photometric data. There is a second method for determining As a first method, Japanese Patent Publication No. 56-15492, Japanese Patent Publication No. 59-29847,
JP-A-52-156624, JP-A-53-1230, JP-A-58-118636, JP-A-59-220760, JP-A-SHO
There are techniques described in Japanese Patent Laid-Open No. 59-220761 and the like, and photometric data not selected by these techniques are excluded from consideration in determining the exposure amount. Therefore, for an image with a small number of selected photometric data, that is, an image with a large color deviation,
Since the exposure amount is determined by a small number of photometric data, the exposure amount determination accuracy is not necessarily high, and as a result, the printed color may have a problem. Also, in an image with a large color deviation, there is a color shift in the selected photometric data, and it is not possible to perform sufficient color area correction.
There is a problem. Furthermore, in an image in which the color deviation is very large, the photometric data may be discarded as a result of selection. In this case, the average value of three colors of B, G, and R screen average densities is often used. However, in such a method, since the characteristics of the photographic image are not included, the ability to correct different types of films is reduced.

The second method is to classify the photometric data by determining which of the high-saturation region and the low-saturation region provided on the color coordinate the photometric data is classified into Weighted average of MD _H and MD _L of the area photometric data
There is a method of determining the exposure amount based on Dj (Japanese Patent Laid-Open No. 61-
(198144 publication).

In this case, since it is necessary to reduce the influence of the average value MD _{H in} the high saturation region, the value of the constant Ka is set to a value of about 0 to 0.4, but in an image with a large color deviation, the average value MD _H is the exposure amount. It greatly influences the decision and cannot perform sufficient color area correction. On the other hand, Japanese Patent Application Laid-Open No. 61-223731 discloses that the average value MD _{H of the} equation (2) is converted into a value D _W indicating an achromatic color to determine the exposure amount. However, since this value D _W is a value obtained from the average value MD _{H in the high} saturation region, the collection for the film type different from the above, that is, the collection for the characteristics of the color image becomes insufficient.

The present invention has been made to solve the above-mentioned problems, and prevents color fading at the time of exposure of a color photographic image and also has characteristics of a color photograph (sensitivity and balance, gamma and balance, minimum density color balance exposure amount). It is an object of the present invention to provide a method for determining an exposure amount of an image copying apparatus in which an appropriate copy can be obtained from any color photographic image by correcting the shape of the density characteristic curve).

[Means for solving the problem]

In order to achieve the above object, the present invention divides a color photographic image into a large number to measure R, G, and B lights, and also provides a plurality of color coordinate data in which three-color photometric data by the photometry is preset. The photometric data is classified by determining which one of the color areas divided into, the photometric data belonging to the color area having a small color difference or color ratio from the reference value is the first image data, and the first photodata The exposure value is determined based on the characteristic values of the three primary colors obtained from the first and second image data, using the representative value of the image data or the reference value as the second image data.

Also, all or some of the photometric data belonging to the color region having a large color difference or color ratio from the reference value is converted into the second image data, and the three primary colors of the three primary colors obtained from the first and second image data are converted. The exposure amount can be determined based on each characteristic value.

Each characteristic value of the three primary colors may be a weighted average value of characteristic values obtained from the first image data and characteristic values obtained from the second image data.

Furthermore, the color photographic image is divided into a large number of R, G, B
Along with photometry of light, the photometric data is classified by judging which of the color regions the three-color photometric data by the photometry belongs to is divided into a plurality of preset color coordinates, and the photometric data is classified from the reference value. A characteristic value obtained from photometric data belonging to a color region having a small color difference or color ratio, and an exposure amount based on a representative value of the photometric data belonging to a color region having a small color difference or color ratio from the reference value or the reference value. You can also decide.

At least two or more color areas divided into the plurality of color areas can be defined according to a value on a color coordinate from a value relating to a specific color of a photographic image or a reference value obtained from a large number of images. In this case, the specific color may be a neutral color, a flesh color, or a color determined from the average value of the multiple images.

Further, the representative value may be an average value of photometric data of a color region to which the photometric data having the smallest color difference or color ratio from the reference value of at least the color photographic image belongs.

[Action]

In the present invention, a plurality of color areas are provided on preset color coordinates. As the color coordinates, one color or two colors or more combinations of the three primary colors _{(e.g., D x -D y, D x} / D y, D x / (D x + D y + D z), D x + D y +
D _z , D _x -K, D _x / K, etc., where x, y, and z represent one color of R, G, and B, which are different from each other, and K is a constant. ) Can be used for two-dimensional or three-dimensional color coordinates. In addition, the color area can be defined according to the distance from the origin of the color coordinates or the point indicating the reference value described below.

The photometric data is obtained by dividing a color photographic image into a large number and measuring the R, G, and B lights. Each photometric data is calculated and converted into a point in the color coordinate system, and it is determined which of a plurality of predetermined color regions in one or a plurality of color coordinates belongs to and is classified. The representative value is obtained from the photometric data (first image data) belonging to the color area having a small color difference or color ratio from the reference value. As the reference value, a value relating to a specific color of a photographic image, a value obtained from an average value of many images, a minimum value of photometric data, a value obtained from photometric data of a specific image, a predetermined constant value, etc. Can be adopted. Further, the reference value may be a value given by a functional expression or a table. In this case, for example, a functional expression or a table value in which the reference value changes depending on the image density may be used. As the specific color of the photographic image, a neutral color, a flesh color, or a color obtained from the average value of many images can be adopted. Further, as the representative value, the average value of the photometric data belonging to the color region where the color difference or color ratio from the reference value is small, the intermediate value of this photometric data, and one value of this photometric data (for example, the most A value with a small color difference or color ratio, the maximum value of this photometric data, etc.), a color difference of the average value or a color ratio of the average value obtained from this photometric data, and the like can be used. Furthermore, the average value of the photometric data of the color region to which the photometric data having the smallest color difference or color ratio of the color photographic image belongs can be used as the representative value. As described above, since the representative value is obtained from the photometric data that belongs to the color region where the color difference or the color ratio from the reference value is small, that is, the photometric data with little color deviation, this representative value has different types (sensitivity, manufacturer, It is a value that includes the characteristics of the color photographic image (use etc.). When this color area includes the reference value, the representative value is close to the reference value. When the standard value is set for the film type,
A reference value may be used instead of the representative value.

Then, each of all or some of the photometric data belonging to the color region having a large color difference or color ratio from the reference value is converted into the representative value or reference value (second image data) obtained as described above, The characteristic values of the three primary colors are obtained based on the first image data and the converted second image data that belong to the color region having a small color difference or color ratio, and the exposure amount is determined. The first image data is photometric data of a color area having a small color difference or color ratio from the reference value, and the second image data is data obtained from the representative value or the reference value obtained from the first image data. . As the characteristic values of the three primary colors, the three values of the average value obtained from the first and second image data, the weighted average value, the average value of data excluding a large value or small value of the photometric data, and the like are set. It is a value. The exposure amount may be determined based on the characteristic value from the first image data and the representative value or the reference value. When converting the photometric data into a representative value, it is also preferable to increase the conversion ratio to the representative value in a color region having a higher color difference or color ratio.

〔The invention's effect〕

As described above, according to the present invention, the exposure amount is determined using the reference value or the representative value obtained from the photometric data with a small amount of deviation for the photometric data with a large amount of deviation. It is possible to properly determine the amount, and it is possible to obtain an effect that a color print area is prevented from occurring and a stable and good color print image can be created more than ever before.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a schematic diagram of an automatic printer in which the present invention can be implemented. A lamp house 10 having a mirror box 18 and a halogen lamp is arranged below the color negative film 20 loaded in the negative carrier and conveyed to the printing section. A dimming filter 60 is arranged between the mirror box 18 and the lamp house 10. As is well known, the light control filter 60 is composed of three filters, a Y (yellow) filter, an M (magenta) filter, and a C (cyan) filter.

Above the negative film 20, a lens 22, a black shutter 24, and a color paper 26 are arranged in order, and the light rays emitted from the lamp house 10 and transmitted through the dimming filter 60, the mirror box 18, and the negative film 20 are lens 22. To form an image on the color paper 26.

A photometer 28 in a direction tilted with respect to the optical axis of the imaging optical system and at a position where the image density of the negative film 20 can be measured.
Is arranged. The photometer 28 is composed of a two-dimensional image sensor, a line sensor, or the like, and as shown in FIG. 2, the negative image is surface-divided into a large number of pixels Sn and photometry is performed along the scanning line SL. In this case, photometry of each pixel is performed for B, G, and R3 primary colors.

The photometer 28 is connected to a color coordinate calculation circuit 30 which calculates the values of RG and GB based on the photometric data. The color coordinate calculation circuit 30 is connected to the data classification circuit 34. A color area storage unit 32 is connected to the data classification circuit 34. As shown in FIG. 3, the color area storage unit 32 is defined on two-dimensional color coordinates with the RG (= RG) axis as the horizontal axis and the GB (= GB) axis as the vertical axis. In addition, three color areas, that is, a neutral color area (A area), a low saturation color area (B area), and a high saturation color area (C area) are stored in advance. The scale interval ΔD of the coordinate axes of the two-dimensional color coordinates is 0.08, for example.
And each color area is defined at a position corresponding to the distance from the origin. Therefore, the reference value in this embodiment is the origin coordinates.

In the data classification circuit 34, it is determined by deciding which part on the two-dimensional color coordinates the point indicating the RG value and the GB value of each pixel calculated by the color coordinate calculation circuit 30 is located. The metering data is classified by determining which color area the pixel metering data stored in the color area storage unit 32 belongs to. Here, the photometric data included in the area A is CA _ij , the photometric data included in the area B is CB _ij , the photometric data included in the area C is CC _ij, and the number of data in each area is
NA, NB, NC. However, i indicates the number when the photometric data in each area is virtually assigned, and j indicates B,
One of G and R is shown.

In the representative value calculation circuit 36 and the representative value setting circuit 38, the representative value is calculated according to the number of photometric data existing in each color area, as in the first embodiment shown in the following (1) to (3). C
This representative value is set to each of the photometric data CC _ij of the area, and the photometric data is converted.

(1) When NA ≠ 0 and NB ≠ 0, the representative value calculation circuit 36 uses MDA _j = (ΣCA _ij ) / NA or MDAB _j = (Σ
Calculate CA _ij + ΣCB _ij ) / (NA + NB).

Then, in the representative value setting circuit 38, C C _ij = MDA _j and C
Set the average value of the photometric data of the A area to all the photometric data of the area and convert, or set CC _ij = MDABj to the average value of the photometric data of the A and B areas to all the photometric data of the C area. Set and convert.

(2) When NA = 0 and NB ≠ 0, the representative value calculation circuit 36 calculates MDB _j = (ΣCB _ij ) / NB as a representative value. Then, the representative value setting circuit 38 sets CC _ij = MDB _j and sets the average value of the photometric data of the B area to all of the photometric data of the C area and performs conversion.

(3) When NA = 0 and NB = 0, the representative value calculation circuit 36 calculates MDC _j = (ΣCC _ij ) / NC as a representative value. Then, the representative value setting circuit 38 sets CC _ij = MDC _j and sets the average value of the photometric data of the C area to all the photometric data of the C area and converts the data.

Then, Dj The arithmetic circuit 40 following (3) Printer control value in accordance with equation Dj (corresponding to D _j of the expression (1)) is calculated, B according to the exposure control circuit 42 in the above (1), G, The printing exposure amount of each R is calculated, and the printing exposure amount is controlled by inserting a filter of a color having too much light amount into the optical path to shield the light.

However, CA _ij and CB _ij are the first image data, TCC _ij are the second image data, and indicate the conversion value of the C area converted by the representative value setting circuit 38.

Next, referring to FIG. 4, the correction of the green color area will be described by comparing the conventional example with the above-described embodiment. FIG. 4 shows the distribution of photometric data in three concentric circles in the color coordinates with the axes R-G and G-B, and also shows the color regions CA, CB, CC. For negative film images containing many green subjects, the photometric data is RG <
0, G-B> 0 are present at a large number of coordinate positions, and in the figure, the central circle has a large distribution of photometric data on the color coordinates. Since the conventional method discards the photometric data in the high saturation color area, the printer control value Dj 'is as follows.

Dj ′ = (ΣCA _ij + ΣCB _ij ) / (NA + NB) (4) On the other hand, the printer control value of the above embodiment is expressed by the equation (3). However, here TCC _ij = MDA _j
(Corresponding to the case (1) of the embodiment). , Indicate the positions on the color coordinates of the values of Dj ′ and Dj obtained by the expressions (4) and (3). In the case of, the G concentration is large, and it is expected that color areas will still occur.

However, when NC is large such as (NA + NB) / (NA + NB + NC) <0.5, | D _R ′ −D _G ′ | <| D _R −D _G ｜ and | D _G ′ −D _B ′ | <| D _G -D _B | and the conventional point shown in FIG. 4 becomes the point in the present embodiment, so that the color fuser correction is performed more sufficiently than before without lowering the correction capability of different types of films. be able to. Also, in equation (4), the larger the color deviation
Although D _j ′ also increases, the correction capacity of the color area increases as the color deviation increases in the equation (3) of the present invention.

When TCC _ij = MDC _j (corresponding to the case of (3) in the embodiment), the above expression (3) becomes equal to the average density of the high saturation image portion (C area) in the image. An image having only such a high saturation is an image including strong different light sources. By controlling the exposure according to the density of the high saturation image area,
Even for different types of films, it is possible to perform correction for the strong different light source.

As in this embodiment described above, the A region or A, B
By converting the average value of the area and the photometric data of the area C, the high-saturation image portion in the image is converted into a full-screen low-saturation image in consideration of the characteristics of the film. It is possible to perform more stable and sufficient color area correction than before without lowering the film correction capability.

Next, a second embodiment of the present invention will be described. In the present embodiment, as shown in FIG. 5, on the two-dimensional coordinates described above, a low-saturation color area surrounded by a circle C1 centered on the origin and a high-saturation color other than this area. A region is provided, and the color region having low saturation is divided into concentric regions A1 to A3, and the color region obtained by dividing the region having high saturation into radial regions A4 to A9 is stored in the color region storage unit 32. The exposure amount is determined as follows. Here, the photometric data belonging to each area is CA1 _ij , CA2 _ij , CA3 _ij , ... CA9 _ij (generally represented as CAl _ij ), and the number of data in each area is NA1, respectively. NA2 ... NA9 (generally referred to as NAl). However, i represents the number when the photometric data included in each area is virtually numbered, and A1
I = 1 to NA1 in the region, i = 1 to NA2 in the A2 region ... i = 1 to NA9 in the A9 region, and j is any one of B, G, and R.

First, the average value of the photometric data belonging to the A1 area Look, a conversion value obtained by converting the photometric data of the regions A1~A9 on the average value (corresponding to the representative value) and CBL _ij. Then, using the photometric data CAl _ij (first image data) and the conversion value CBl _ij (second image data), a weighted average value Xj is calculated according to the following equation.

However, KAl and KBl are constants determined so as to change from the low saturation side to the high saturation side (as l increases) as shown in Table 1 below.

In this way, as the saturation increases, KAl decreases and KBl increases.Therefore, the higher the saturation, the greater the reflection ratio of the conversion value to the average value Xj. Can be large.

The average value Xj is set as the print control value Dj. Furthermore, the conversion value CBL _ij is separated into density component and the color component, and corrects the print control values Dj seeking color correction from the average value Xj may be determined exposure amount.

As described above, in the present embodiment, the average value of the photometric data of the color region with the lowest saturation is used as the representative value, and the weight of the photometric data is reduced and the weight of the representative value is increased as the saturation of the color region increases. The exposure amount is determined by using the average value calculated in the above.

Next, a third embodiment of the present invention will be described. In this embodiment, the average value Xj of the second embodiment is calculated by the following formula. CBl _ij is the converted value of the second embodiment.

However, kl is 0 which includes 0 and at least one value other than 0
Kl 'is a coefficient that decreases with an increase in kl, and kl' is a coefficient that increases with an increase in l having at least one value other than 0 including 0. In the present invention, as in the present embodiment, the characteristic value MDAl _j obtained from the first image data and the second characteristic value MDAl _j
The exposure amount may be obtained using the characteristic value MDBl _j obtained from the image data.

The exposure amount is determined as Dj ′ = Dj + ΔXj by determining Xj in the above equation (6) as Dj or obtaining the color correction amount ΔXj from Xj as follows.

 The correction amount Xj is as follows, for example.

ΔX _B = (X _B −X _G ) + (ΣXj ′ / 3−ΣDj / 3) ΔX _G = (ΣXj ′ / 3−ΣDj / 3) ΔX _R = (X _R −X _G ) + (ΣXj ′ / 3 −ΣDj / 3) However, In this case, Dj may be LATD, or may be the whole or part of the screen average density.

Next, a fourth embodiment of the present invention will be described. In this embodiment, the color regions are divided into concentric circles as shown in FIG.
It uses two areas. In the present embodiment, the photometric data used in the present invention is gradually shifted to the high saturation side according to the number of photometric data, and any one of the following methods (1) to (4) may be adopted. it can. The following N1, N2 ...
N6 indicates the number of data in the areas 1, 2, ...

(1) Method 1 (a) When N1 ≠ 0, the data in areas 1, 2, and 3 are used.

(B) When N1 = 0 and N2 ≠ 0, the data in the areas 2, 3, and 4 are used.

(C) When N1 = N2 = 0 and N3 ≠ 0, the data of areas 3, 4, and 5 are used.

(D) When N1 = N2 = N3 = 0 and N4 ≠ 0, areas 4, 5, and 6
Use the data of.

Then, as described in the above embodiment, the exposure amount is determined by converting the data belonging to the high saturation region into a representative value obtained from the data belonging to the low saturation region.

(2) Method 2 (a) When N1 ≠ 0, the individual data in the areas 4, 5, and 6 are converted into the representative value of the data in the area 1.

(B) When N1 = 0 and N2 ≠ 0, the individual data in the areas 5 and 6 are converted into the representative value of the data in the area 2.

(C) When N1 = N2 = 0 and N3 ≠ 0, the individual data in the area 6 is converted into the representative value of the data in the area 3.

Then, the exposure amount is determined from the data thus converted.

The first to fourth embodiments have been described above by using the representative value of the photometric data that belongs to the color region where the color difference or the color ratio from the reference value is small. The first to fourth examples can be performed by using the reference value instead of the representative value, and similar effects can be obtained. The representative value is superior to the reference value in that it can represent a characteristic change for each film, but on the other hand, there are cases where the stability is lacking and it is better to use the reference value.

Next, a fifth embodiment will be described. In FIG. 3, when the (K-NA-NB)> 0, Dj = (ΣCA ij + ΣCB ij + (K-NA-NB) · MDAj) / K {K: constant, for example, the number of all the photometric data 1 / Value of 3} (K-NA-NB) ≤ 0, the number of photometric data in a color region having a small color difference or a small color ratio with respect to the reference value is predetermined such as Dj = (ΣCA _ij + ΣCB _ij ) / (NA + NB). If the number is less than
The representative value of the color area having the smallest color difference or color ratio than the reference value is used. As a result, it is possible to prevent a decrease in density due to a lack of the number of data in the A and B color areas. As described above, the reference value may be used instead of the representative value.

It should be noted that the distance obtained by a predetermined method with reference to the measurement point closest to the neutral color or the measurement point group closest to the neutral color without dividing the two-dimensional or three-dimensional color coordinate as a region. The exposure amount may be determined by the photometric data within the range. Further, even if the color region is determined using three-dimensional coordinates including polar coordinates as shown in FIG. 7 and density axes (G, (B + G + R) / 3, etc.) shown below and the following two two-dimensional color coordinates. Good.

Further, the coefficients KA, KB, k, k ′ described above may be changed depending on the image content (for example, artificial light, light source color temperature, etc.) and image density (underexposure, overexposure, etc.). This change may be prepared and selected for each case, or may be calculated by a function and changed. Further, changing the color area A according to the density of the photographic image as shown in FIG. 8 is a preferable method because the accuracy of exposure control of the photographic image of underexposure can be improved.

Although the photographic printing apparatus has been described above, it can be effectively applied to an image copying apparatus such as a color copying apparatus or an electronic camera which controls the exposure amount based on the photometric values of the three primary colors.

[Brief description of drawings]

FIG. 1 is a schematic view of an automatic printer to which the present invention is applicable, FIG. 2 is a diagram showing a state in which surface division is used for photometry, FIG. 3 is a diagram showing color regions, and FIG. 4 is a green color diagram. Diagrams for explaining correction of fueria, FIGS. 5 and 6 are diagrams showing other examples of color regions, FIG. 7 is a diagram for explaining axes of color coordinates, and FIG. 8 is three-dimensional color coordinates. FIG. 30 ... Color coordinate calculation circuit, 32 ... Color area storage unit, 34 ... Data classification circuit, 36 ... Representative value calculation circuit, 38 ... Representative value setting circuit, 40 ... Dj calculation circuit, 42 ... Exposure Control circuit.

Claims (7)

(57) [Claims] 1. A color photographic image is divided into a plurality of R images,
G and B lights are measured, and the photometric data is classified by determining which of the plurality of divided color areas on the preset color coordinates the three-color photometric data obtained by the photometry belongs to. The photometric data belonging to the color region having a small color difference or color ratio from the values is used as the first image data, and the representative value of the first image data or the reference value is used as the second image data. 3 obtained from image data
An exposure amount determining method for an image copying apparatus, characterized in that the exposure amount is determined based on each characteristic value of the primary colors. 2. All or part of the photometric data belonging to a color region having a large color difference or color ratio from a reference value is converted into the second image data, and is obtained from the first and second image data. An exposure amount determining method for an image copying apparatus according to claim 1, wherein the exposure amount is determined based on each characteristic value of the three primary colors. 3. The image copy according to claim 1, wherein each characteristic value of the three primary colors is a weighted average value of characteristic values obtained from the first image data and characteristic values obtained from the second image data. Method for determining exposure amount of apparatus. 4. A color photographic image is divided into a plurality of R images,
G and B lights are measured, and the photometric data is classified by determining which of the plurality of divided color areas on the preset color coordinates the three-color photometric data obtained by the photometry belongs to. Based on the characteristic value obtained from the photometric data belonging to the color region having a small color difference or color ratio from the value and the representative value or the reference value of the photometric data belonging to the color region having a small color difference or color ratio from the reference value An exposure amount determining method for an image copying apparatus, characterized in that the exposure amount is determined. 5. The color area divided into the plurality of areas is at least 2 according to a value on a color coordinate from a value relating to a specific color of a photographic image or a reference value obtained from a large number of images.
An exposure amount determining method for an image copying apparatus according to claim 1 or 4 defined above. 6. The exposure amount determining method for an image copying apparatus according to claim 5, wherein the specific color is a neutral color, a flesh color, or a color determined from an average value of the plurality of images. 7. The representative value is an average value of the photometric data of a color region to which the photometric data having the smallest color difference or color ratio from at least the reference value of the color photographic image belongs. A method for determining an exposure amount of the described image copying apparatus.