JPH0346648A - Exposure quantity deciding method for image copying device - Google Patents

Abstract

PURPOSE:To attain high speed printing processing without the need of information showing the kind of film by selecting three color photometric data according to the classification of three color standardizing data and deciding exposure quantity based on the average value of the selected three color photometric data. CONSTITUTION:Three color photometric data is obtained by dividing color film, wherein a picture is recorded into plural frames and photometoring them, and three color corrected photometric data is obtained by correcting the three color photometric data by photometric data on the low density part of the color film containing a picture recorded part. The three color standardizing data is obtained by converting the three color corrected photometric data according to prescribed converting conditions and standardizing them, and the three color standardizing data is classified by comparing the three color standardizing data with a reference value. Then, the three color photometric data is selected according to the classification of the three color standardizing data, and the exposure quantity is decided based on the average value of the selected three color photometric data. Thus, since the photometric data on the low density part of the color film can be obtained without photometoring a roll of the film, high speed printing processing can be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for determining the exposure amount of an image copying device, and particularly to an automatic photo printing device (automatic photo printing device) that prints an image from a color photograph such as a color film onto color paper. The present invention relates to a photographic printing exposure amount determination method for determining the exposure amount of a printer (printer).

[Prior art and problems to be solved by the invention] Color negatives have three colors of B (blue), G (green), and R (red) as a whole screen.
It transmits colored light, and it is known from experience that the transmission ratios of these three envelope components are generally approximately equal or at a constant ratio. For this reason, automatic printers determine the amount of printing light (exposure amount) based on the following equation.

1, ogF j=K j+D j...(1
) However, 1. gogF is the logarithm of the amount of printing light, K is a constant, and D
is the negative cumulative transmission density (LΔTD) measured with a photometric system,
j is either B or GXR color light.

However, if the amount of printing light is controlled by an automatic printer based on equation (1) above, prints from underexposed negatives will have higher overall density than prints from properly exposed negatives, and prints from overexposed negatives will have higher density than prints from properly exposed negatives. becomes lower. Therefore, by providing a slope control circuit, D of equation (1) is
The exposure amount is determined by correcting j. on the other hand,
Even in an automatic printer equipped with a slope control circuit as described above, negatives that have significantly deteriorated over time, negatives that were photographed under a light source that is significantly different from daylight (fluorescent lamp, tungsten lamp, etc.) (different light source negatives), and color area With negatives and the like, defective prints with incorrect color balance are likely to occur. Further, film manufacturers and film types with different sensitivities (different types of films) have different sensitivities, densities, etc. of the three photosensitive layers, and good prints cannot be produced under the same printing conditions. For this reason, the exposure amount is determined by correcting Dj in equation (1) (color correction) and by changing the slope control circuit value for different types of films. At this time, excessive correction with respect to standard correction (normal correction) is called high correction, and undercorrection is called lower correction. In the case of high correction, a collar area occurs, and in the case of lower correction, RXG.

The accuracy of B deteriorates.

However, in recent years, various manufacturers have released high-sensitivity films, films for different uses, new films with various improvements, etc. every year, and the variety of films has become extremely large.
There are now dozens of types. However, since the printing exposure conditions for each film type do not necessarily match, it is necessary to determine the printing exposure conditions for each film type, and the process of determining the printing exposure conditions involves a lot of trial and error, and requires a lot of skill and skill. It takes time. For this reason, the following technique has been proposed for automatically determining appropriate printing exposure conditions for each film type from one reference printing exposure condition.

Japanese Patent Publication No. 56-15492 discloses that the ratio of the color density of the photometric value of each point of the image B/GSG/R, R/B is compared with a fixed value, and one of the three primary colors is compared with the other primary color. It is disclosed that a large photometric value is not used for determining the exposure amount. Also, JP-A-51-949
Publication No. 27 discloses a technique for determining the exposure amount based on a photometric value obtained by removing a photometric value that deviates by a certain amount from the reference value of a standard image of each film type. These technologies require comparison values and reference values specific to the film type to be provided, so it is necessary to manually generate data indicating the film type, as well as create and store comparison values and reference values in the film seeding process. There is a drawback.

In order to solve this drawback, patent application No. 63-245810
In the issue, a large number of image densities are stored for each film type in correspondence with the code indicating the film type stored in the film, and a reference value for each film type is determined from the stored data, and the code is read and printed. It is disclosed that the film type of the film to be printed is determined, and the exposure amount of the film to be printed is determined from the photometric value of the film to be printed selected and determined with respect to a reference value and standard printing exposure conditions. . According to this method, it is possible to automatically determine the reference value, but it cannot be applied to film types that do not have information such as codes indicating the film type (for example, 110 film, Brawny film, disc film, etc.). There are drawbacks.

A method of determining the exposure amount for printing without using information on the film type is to select the photometric value and determine the exposure amount using a curve showing the color balance characteristics determined from the photometric value each time the original is copied on the film. is known (Japanese Unexamined Patent Publication No. 55-46741). However, this method involves determining a color balance characteristic curve from a test exposed area printed on a film, which is quite difficult in practice.

The technology described in Japanese Patent Application Laid-Open No. 54-110829 is
The exposure amount is determined from a large number of photometric values of one film image, and it is necessary to know the photometric power of one film<fg before printing.

For this reason, it is possible to separate the photometry section and the exposure section as in the technique described in JP-A No. 59-220761, or to place the photometry section in the same place as in the technique described in JP-A-61-91648. In an apparatus having a printing section and a printing section, it is necessary to transport the film in the opposite direction once it has been transported for photometry and printing, making it difficult to increase the speed. Another drawback is that the film is more likely to be damaged because the film is transported many times.

Furthermore, Japanese Patent Application Laid-Open No. 59-220760 discloses that the lowest density point including the mask density is determined in or around the original image of the film strip, and as the neutral density of the measurement point increases with respect to the lowest density point, the The limit value of the chromaticity of the point is expanded, and the value for the lowest density of each measurement value obtained by scanning the original copy of the three primary colors is compared with the above limit value to find a photometric point that does not exceed the above limit value. The selection is disclosed. This technique relies on the fact that the lowest density measurement point of the film strip to which the negative and its surroundings or original belongs is close to the mask density and therefore the chromaticity of the individual images is also not large.

However, this method has the following drawbacks.

That is, film characteristics (three-color sensitivity balance, three-color gradation balance, linearity of characteristic curve, etc.) cannot be known from the mask density. For this reason, a method for determining the limit of the measurement point for the lowest density point is predetermined, but this method is insufficient to account for the effects of film types, negative development performance variations, differences in photometers, and the like.

Therefore, the color balance characteristic curve described above is further determined for the value (photometric value) of the selected photometric point. However, for this reason, the drawbacks mentioned in Japanese Unexamined Patent Publication No. 55-4674↓ remain unsolved.

The present invention was developed to solve the above problems, and enables high-speed printing processing without requiring information indicating the film type when printing various films under the printing exposure conditions of the standard film type. An object of the present invention is to provide a method for determining an exposure amount for an image copying apparatus.

[Means to solve the problem]

In order to achieve the above object, the present invention obtains three-color photometric data by dividing a color film on which an image is recorded into a large number of parts and photometrically measuring the low-density part of the color film including the image recording part. obtaining three-color corrected photometric data by correcting the three-color photometric data according to the data;
The three-color corrected photometric data is converted and standardized according to predetermined conversion conditions to obtain three-color normalized data, and the three-color normalized data is compared with a reference value to perform the three-color normalization. The data is classified, the three-color photometric data is selected according to the classification of the three-color normalized data, and the exposure amount is determined based on the average value of the selected three-color photometric data.

Further, the three-color standardized data can be classified by determining to which of a plurality of predetermined two-dimensional or three-dimensional coordinate regions the three-color standardized data belongs.

Low-density area photometry data shall be the lowest density data of the image recording area of the color film, the lowest density data of areas other than the image recording area of the color film, and the lowest density data of the area spanning adjacent images recorded on the color film. be able to.

[Effect]

The present invention will be explained in detail below. Figure 2 is A, B, C, D
A standard subject was photographed using four types of negative film with the exposure amount sequentially changed, and the average density determined by photometry of the film images is shown with the horizontal axis as R-G and the vertical axis as G-B. This is shown on the color coordinates.

FIG. 3 shows the image density obtained by subtracting the mask density of the film from each average density shown in FIG. 2 on the color coordinates. As can be understood from FIG. 3, the densities of the image areas of each film obtained by subtracting the mask density from the average density are approximately similar, except for the high density of film C. FIG. 4 shows the average density of a large number of images (approximately 100 frames) of the above-mentioned four types of negative films divided into four density levels and shown on color coordinates.

The upper end of the broken line indicates the mask density. Three of the four films are very different. Figure 5 shows the densities obtained by subtracting the mask density from each average density and the average value of the densities of the four films on the color coordinates, and as in Figure 3, the densities of the film image areas are almost similar. There is.

However, until recent years, there was no such agreement with negative films. In most cases, a combination of one or only a few manufacturers' negative film and paper is used, and it is sufficient to obtain good photographic prints with that combination. The other combination was not sufficiently considered. However, in recent years, as a result of the spread of various films worldwide, the number of cases in which various negative films and various color papers are combined has become enormous.

In order to be able to use any combination, the gradation balance characteristics of each film must be similar. The results shown in FIGS. 2 and 4 show that the gradation balance characteristics of the various films are similar.

However, the characteristics of the coloring materials used in each film are naturally not the same, and the photosensitive material design technology is also not the same, so the mask density does not match for each film type.

Figures 6 and 7 show the values obtained by subtracting the low-density photometric data of the image area of the film from the average density instead of the mask density on the same color coordinates as in Figures 3 and 5. . There is better agreement in the critical density range for the four films than by subtracting the mask density.

Therefore, the average density value of the two films obtained by subtracting the photometric data of the low density area 2 including the mask density from the photometric value can be used as the image area characteristics of various films. Further, the average value of a plurality of the above-mentioned average density values can be used for various films.

As explained above, the data obtained by subtracting the mask density or a low density close to it from the average density, that is, the lowest density data other than the image recording area of a color film, or the lowest density data of the image recording area of a color film, is obtained regardless of the film type. The three-color photometric data is similar. For this reason, in the present invention, a color film on which an image is recorded is divided into a large number of pieces, and photometry is performed to obtain the three-color photometry data. Three-color corrected photometric data is obtained by correcting the color photometric data with the low-density area photometric data. This three-color corrected photometric data is converted into three-color standardized data by being normalized according to predetermined conversion conditions. This three-color normalized data is classified by being compared with a reference value, three-color photometric data 3 is selected according to this classification, and the exposure amount is determined based on the average value of the selected three-color photometric data. .

As explained regarding the mask density, since the mask density is not the same for each film type, it is preferable to determine the low density area photometric data for each type of color film.

〔Effect of the invention〕

As explained above, according to the present invention, the exposure amount is determined using the three-color corrected photometric data obtained by photometrically measuring the color film and correcting the three-color photometric data with the low-density area photometric data in the color film. Since this three-color corrected photometry data is approximate regardless of the film type, it is possible to determine the exposure amount of various films using the exposure amount of the reference film type without using film type information. Effects can be obtained.

Further, since the photometric data for low density areas in a color film can be obtained without photometrically measuring one film, it is possible to perform high-speed printing processing.

4 〔Example〕 Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 8 shows a schematic diagram of an automatic printer capable of implementing the present invention. Below the color negative film 20 loaded in the negative carrier and conveyed to the printing section, there are
A mirror box 18 and a lamp house 10 equipped with a halogen lamp are arranged. A light control filter 60 is arranged between the mirror box 8 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 (macenter) filter, and a C (cyan) filter.

A lens 22 , a black shutter 24 , and a color paper 26 are arranged in this order above the negative film 20 , and are illuminated by light from the lamp house 10 to a dimming filter 60 .
The light beam transmitted through the mirror box 18 and the negative film 20 is configured to form an image on a color paper 26 by a lens 22.

Step 5 Place the photometer 2 in a direction oblique to the optical axis of the imaging optical system and in a position where the image density of the negative film 20 can be photometered.
8 is placed. The photometer 28 is composed of a two-dimensional image sensor, a line sensor, etc., and as shown in FIG. 9, divides the negative image into a large number of pixels Sn and measures the light along the scanning line SL. In this case, the photometry of each pixel is B, G,
This is done for the R3 primary colors.

The photometer 28 is connected to a calculation circuit 30 composed of a microcomputer or the like that calculates the printing exposure amount. The arithmetic circuit 30 is connected to a memory 34 that stores data and an exposure amount control circuit 42 that controls the printing exposure amount by controlling a dimming filter 60 based on the exposure amount calculated by the arithmetic circuit 30. .

Next, the exposure amount calculation routine by the calculation circuit 30 will be explained based on FIG. In step 100, the photometer 28
Step 101
, it is determined whether the photometry at the initial stage of printing, i.e., the photometry is for the start image frame or several frames (up to about 6 frames) from the 6th image frame on the printing surface, and if the photometry is at the initial stage of printing, the process proceeds to step 102, and the photometry at the initial stage of printing is performed. If not, proceed to step 104. In step 102, the average mask density previously stored in the memory 34 is used to calculate the three color low density area photometric data MIN(R), MIN(G), MIN(B) as shown below, and the data are stored in the memory 34. Remember. Note that this average mask density is obtained by averaging the mask densities or average minimum densities of various films. A predetermined value α(
For example, compare the large value (0 to 0.6) with the lowest density value of the three-color photometric data or the average value of the three-color photometric data, and then (low density value or average value of the three-color photometric data), the lowest density value of the three-color photometric data or the average value of the three-color photometric data is used as the low-density portion photometric data. On the other hand, when (average mask density 10α)<(lowest density value of three-color photometric data or average value of three-color photometric data), a value larger than the average mask density by a predetermined value α is set to the low-density part photometric de7 - to

Note that, as shown in FIG. 10, the lowest density value of the three-color photometry data when photometry is performed with the photometry area 32 of the photometer 28 spanning the image frames 2OA and 20B may be used as the low-density area photometry data. . In addition, the mask density, which is low-density area photometry data, is stored in advance in the memory 34 for film seeding, and the film type is determined by detecting a so-called DX code indicating the film type, and the low-density area photometry is used for film seeding. Data may be defined.

Since the low-density area photometric data is determined as described above, this low-density area photometric data is the lowest density data of the image recording area of the color film, and the lowest density data other than image recording B of the color film (mask density ). This low-density area photometry data is determined by photometry of the starting image frame for printing or several frames (up to about 6 frames) from the starting image frame for printing, which can speed up the printing process.

In the next step 104, three-color corrected photometric data R and GXB are calculated by subtracting low-density area photometric data MIN (R), MIN8 (G), and MIN (B) from each of the three-color photometric data. As already explained, this modified photometric data has similar characteristics regardless of the film type.

In the next step 106, the corrected photometric data R1B is
Three-color normalized photometric data is calculated by converting to G density and normalizing it using the normalization table shown in FIG. This standardization corrects the fact that film density and gradation balance vary depending on the film type and development process, and therefore, when photographing the same subject, the image density and color will differ depending on the film type and development process. This process is intended to produce a constant density and color on negative film for the same subject regardless of the film type or development process. This normalization table also includes a curve showing the relationship between the average value of the photometric data G and the average value of the photometric data R selected in step 110 described below and stored in the memory, and the average value of the photometric data G. It is created based on a curve showing the relationship with the average value of photometric data B. The corrected photometric data R and B are converted to the density of G using the normalization coefficient 9, but as shown in FIG. 11, for example, R2-R
The average value R3 of the corrected photometric data of No. 3 is converted to the average value G3 of G2 and G3, and the average value B3 of the corrected photometric data of No. 32 to B3 is similarly converted to the average value G3. At this time, the corrected photometric data G is used as is without being converted. As this standardization method, in addition to the above methods, methods described in Japanese Patent Application Laid-Open No. 56-1039 and Japanese Patent Application Laid-open No. 62-144158 can be used.

By standardizing the corrected photometric data in this way, the same color coordinates can be used even if film densities and film types differ, and the origin of the coordinates can be set to any color. Assuming that the average value of the photometric data of a large number of films is clay, the normalized data of the gray subject becomes the same for the three colors through the above normalization. In reality, the average value of the photometric data of a large number of films is slightly different from the gray value, so it is corrected by an amount corresponding to the difference.

In the next step 108, as shown in FIG. The three-color standardized data is classified by determining to which color area the three-color standardized data belongs, the color area AB including the origin and the color area Ab other than the color area Aa, defined in . The three-color standardized data is classified based on the boundary between the color area Aa and the color area Ab. Therefore, the three-color standardized data is classified as data belonging to an area with a small color difference from the reference value (origin) and the reference value. The data will be classified into data belonging to an area with a large color difference from the value.

The following table shows examples of color regions, three-color standardized data classified for each color region, and three-color photometric data corresponding to the three-color standardized data.

In addition, in the above, three-color standardized data was classified using color coordinates with G-B and R-G as axes. D.
l/DyXD, / (D□1Dri+D2), DX+D
y+D2, DX-, SD8/, etc., however, xly,
, , Z represent one mutually different color of R, G, , B, and K is a constant. ), that is, a coordinate axis having a color difference or color ratio other than the above can be used for two-dimensional or three-dimensional color coordinates. Also,
A plurality of color regions can be defined according to the distance from the reference value. This reference value is the origin of the color coordinates used,
A value related to a specific color of the original image, a value obtained from an average value of a large number of images, a minimum value of photometric data, a value obtained from photometric data of a specific image, a predetermined constant value, etc. can be employed. Furthermore, the reference value may be a value given by a functional formula or a table. In this case, the reference value may be a functional formula or table value whose reference value changes depending on the image density, for example. Note that as the specific color of the original image, a neutral color, a skin color, or a color obtained from the average value of a large number of images can be adopted.

Furthermore, as shown in FIG. 13, a color area having an irregular distance from the origin may be used as the fish head/area, which is provided on coordinates with a neutral color as the origin.

In step 110, three-color photometric data corresponding to the three-color normalized data belonging to the color area Aa with a small color difference from the reference value is selected and stored in the memory 34, and in step 112, the selected three-color photometric data is averaged. Then, the first image data MDa is calculated.

When classifying three-color standardized data by coordinates with color ratio as the axis, select the three-color photometric data that corresponds to the three-color standardized data that belongs to a color area with a small color ratio from the reference value. , the first image data MDa is calculated by averaging these three-color photometric data.

In the next step 114, second image data MDo corresponding to a specific color (for example, a neutral color, a color larger than a neutral color by a certain color difference or color ratio) is calculated. As this second image data MDc, trichromatic photometric data corresponding to the origin of the color coordinates shown in FIG. 12 can be used. This three-color photometric data represents 08 degrees of the (th) image data MD,
(G), this MD' (G) is the first
By performing inverse transformation using the normalization table shown in Figure 1, the R density MD', (R), Bi'! if degree MD',
(B) (Fig. 14), RlG, B concentration MD'c (R), MD'o (G) as shown in the following equation (2).
, density MD'c (B), low density area photometry data M
It is obtained by adding IN (R), MIN (G), and MIN (B).

4 MDo (R)-MD' (R)+MIN(R)M
Do (G) = MD' (G) +
N IN (G)MD, (B)-MD'
(B)+NIN(B)...(2) Then, in step 116, the exposure control value DJ of the print negative is calculated according to the following equation (3), and in step 118, the exposure amount E is calculated according to the following equation (4).
Calculate j. Note that the subscript j indicates RlG and B.

D,=to, ・MDa+KcMDc ・(3)j2
ogE, = ()j l sj (Dj DJON
)+Fj+(1,,...(4) However, Ka and Ke are coefficients for weighting,
+KCξ is a constant value (for example, 1.0), C3 is a color correction coefficient (ξ1.O), S is a slope control coefficient (~0.5 to 2.0), and DjoN is the exposure of the reference image of the reference film type. Control value, Fj is a constant determined by color paper and color printer, d,
is the exposure correction amount based on the image content.

5 The above weighting is the coefficient Ka, Kc is the following (1) to (3)
The following changes may be made depending on the purpose shown in .

(1) When setting exposure conditions, ~0.7~1. 2 (0,9) K, ~0. 5-0. 0 (0,1) (2) When printing manually, ~0. 3-0. 9 (0,7)Kc=0.
7-0. 1 (0,3) (3) During automatic printing, ~0.7~1. 2 (1,0) Kc=0.5~0. 0 (0,0) However, the numbers in parentheses are desirable values.

Furthermore, when setting exposure conditions and manual printing, it is preferable to widen the range of the color area A6 or to cancel the selection of photometric data and use all three-color photometric data. This is the coefficient K. As the coefficient Ka becomes larger, the correction of the film type and artificial light source becomes worse, and the correction of the color area becomes better.As the coefficient Ka becomes larger, the above is reversed, but depending on the selection of photometric data, the value of the coefficient becomes At most 6 Color area correction, film type correction, and artificial light source correction are improved, while color area correction and light source correction are not required when setting exposure conditions or manual printing, making it easier to select photometric data. This is to weaken and stabilize the effects of

By the way, as understood from Figure 3.5.6.7,
The color balance between R and G is approximately constant depending on the density, and G
As the concentration increases, the B concentration becomes higher relative to the Ga degree. Therefore, in this case, it is necessary to know how much the photometric data differs from the photometric data of low density areas such as mask density. When the color balance is allowed to fluctuate by ±0.05 (the image density of a gray subject is
The normalization curve also has a fluctuation range because it changes depending on the photographic light source, camera, film over time, characteristics between lofts, etc., and the tolerance is ±0.05), density (for example (
4 degrees) is ±0. An error of 3 is acceptable. That is, if the error in the image density of the photometric data is within ±0.3, the color balance can be predicted with an error within ±0.05. As a result, the low density photometry data is ±0.0 with respect to the mask density or mask density factor α. It should be within 3.

In the present invention, the comparison reference value for photometric data is not determined for each film strip lapse, but the photometric data is standardized to determine a constant predetermined comparison reference value. Since this normalization condition can be obtained from a large number of image data of one film strip lapse or more, it is possible to obtain the normalization condition with high accuracy. As a result, highly accurate exposure control becomes possible.

Note that in the above, the second image data was determined from the origin of the coordinates in Figure 12, but the second image data was determined from the average value of the trichromatic photometric data of the photometric points included in the neutral area indicated by diagonal lines in Figure 13. may be determined.

Furthermore, data MD'o expressed by the following equation may be used instead of the second image data MD.

MD'o=MDo-, -(5) However, Kj is a correction value to prevent changes in the print color even if the values of , , and Ko are changed, and M
No color change occurs when D'o is equal to the average photometric data of each film type. Further, Kj may be changed depending on the concentration.

Also, if the low-density area photometric data is larger than a predetermined value (in the case of overexposed film), is it possible to correct the low-density area photometric data using a predetermined method without using the low-density area photometric data? When using a predetermined value as the low density photometry data, for example, MIN' (j) -KX, MIN (j) -
(6) (where KX is a coefficient of KX<l, Q), and the determined value can use the average low-density portion data of various films. The present invention can be similarly applied to image display devices such as digital color printers and CRTs.

[Brief explanation of drawings]

Fig. 1 is a flowchart showing the exposure amount calculation routine of the embodiment of the present invention, and Fig. 2 shows film images taken of a standard subject by sequentially changing the exposure amount with four types of A, B, C, and D film. A line diagram showing the average density determined by photometry on the color coordinates, Figure 3 is a line diagram showing the image density obtained by subtracting the mask density from each average density in Figure 2 on the color coordinates, and Figure 4 is the above diagram. A line diagram showing the many average densities of four types of negative films divided into four density levels and shown on the color coordinates. Figure 5 is a line showing the density obtained by subtracting the mask density from each average value on the color coordinates. Figures 6 and 7 are diagrams showing the values obtained by subtracting the low-density area photometric data from the average density on the same color coordinates as in Figures 3 and 5, and Figure 8 is a diagram showing the values obtained by subtracting the low-density area photometric data from the average density, and A schematic diagram of the applied auto color printer. Figure 9 is a line diagram showing the state of photometry by dividing the area, Figure 10 is a line diagram showing the state of photometry of mask density, and Figure 11 shows the normalization curve. Figure 12 is a diagram showing color coordinates for classifying three-color standardized data, Figure 13 is a diagram showing other color coordinates for classifying three-color standardized data, and Figure 14 is a diagram showing the second color coordinate. FIG. 3 is a diagram illustrating how to obtain image data. 26... Color paper, 0 28... Photometer, 60... Light control filter.

Claims (6)

[Claims] (1) Obtain three-color photometric data by dividing a color film on which an image is recorded into many pieces and photometrically measuring the three-color photometric data, and calculate the three-color photometric data using low-density area photometric data in the color film including the image recording section. The three-color corrected photometric data is converted and normalized according to predetermined conversion conditions to obtain the three-color normalized data, and the three-color normalized data is combined with the three-color normalized data. Classify the three-color standardized data by comparing it with a reference value, select the three-color photometric data according to the classification of the three-color standardized data, and determine the exposure amount based on the average value of the selected three-color photometric data. A method for determining the exposure amount of an image copying apparatus. (2) The exposure amount determining method for an image copying apparatus according to claim (1), wherein the low density area photometric data is determined for each type of color film. (3) A claim for classifying the three-color standardized data by determining to which of a plurality of areas divided on predetermined two-dimensional or three-dimensional coordinates the three-color standardized data belongs; The exposure amount determination method for an image copying apparatus according to 1) or (2). (4) Claims (1) to (3) wherein the low density area photometric data is the lowest density data of an image recording area of a color film.
) The exposure amount determining method for an image copying apparatus according to any one of the above. (5) The exposure amount determining method for an image copying apparatus according to any one of claims (1) to (3), wherein the low density area photometric data is the lowest density data of a color film other than an image recording area. (6) The image copying apparatus according to any one of claims (1) to (3), wherein the low-density photometric data is minimum density data of an area spanning adjacent images recorded on a color film. How to determine the exposure amount.