JPH06202248A - Photograph printing exposure deciding method - Google Patents

Abstract

PURPOSE:To provide a photograph printing exposure deciding method by which the setting of an exposure adjusting value for a hue is simplified, storage amount concerning a set value is reduced, and an exposure adjusting value for adjacent hue is automatically generated while keeping the continuity, then an excellently finished print is stably produced. CONSTITUTION:The hue of an original picture is calculated by performing the color separation and the photometry of the original picture on color photographic film (S102), the exposure adjusting value corresponding to the hue of the original picture is obtained by performing the arithmetic interpolation of the exposure adjusting value previously set for the specified hue (S103), and the exposure of respective colors for the original picture is decided basing on the obtained exposure adjusting value (S104). The setting of the exposure adjusting value is simplified and the storage amount concerning the set value is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining a photographic printing exposure amount of an original image recorded on a color photographic film. More specifically, the hue of the photographic original image is evaluated and the printing exposure amount is determined according to this evaluation. It is about how to do it.

[0002]

2. Description of the Related Art In general photography, the subject's blue (B), green (G), red (R) (hereinafter simply referred to as B,
It is known as an empirical rule that the average reflectances of the three primary colors (described as G and R) are substantially constant. Therefore, in the conventional photo printing apparatus, the total area average transmission density (LAT
D) is measured, and the exposure amount in photographic printing is determined based on the measured average transmission density, whereby the exposure amount given to the B, G, and R photosensitive layers of the photographic paper is controlled to be constant,
A photographic print with good color balance is created (usually called "LATD control").

When a film of a standard subject is taken as an object, such an exposure amount control method keeps the exposure amount given to the B, G, and R color photosensitive layers of the photographic paper constant, thereby achieving good color balance. You can create a perfect photo print.

However, in the case of a subject having an inherent bias in luminance distribution and color distribution (called subject ferria), it is difficult to obtain a proper photographic print by the above-mentioned LATD control method. Among these subject ferria, those caused by the unevenness of the luminance distribution of the subject are called density ferria, and those caused by the uneven color distribution are called color ferria.

As a known technique for the purpose of density correction for automatically adjusting the exposure amount for the density ferria, the following technique disclosed in Japanese Patent Publication No. 56-2691 can be cited. That is, the original image on the photographic film is scanned, the characteristic value is obtained for each area of the image from the image density obtained by this scanning, and the classification is performed based on this characteristic value. The function adjusts the exposure amount for the original image.

Further, as a technique aiming at color correction for automatically adjusting the exposure amount for color ferria,
For example, "Exposure" by CJ Hartleson and RWHuboi
Determination Methods for Color Printing: The Conce
pt of Optimum Correction Level ", J.SMPTE, 65,205-215
(1956) can be mentioned.

[0007] In this example, a full collection is prepared in which the exposure amount according to LATD is adjusted for a standard photographic image of a standard subject so that the exposure amount given to each color photosensitive layer of photographic paper is a constant value. It is valid. Also, if the shooting exposure is appropriate, LA for subject feria
No-correction is effective in that exposure is performed with a constant light flux or exposure time regardless of TD. Furthermore, in fact, as a compromise between the two, the low-light collection, which is an intermediate exposure control method for both, is appropriate, and the optimum collection level should be selected from the overall quality of the photographic print. . In recent years, a photo printing apparatus is generally equipped with several collection levels that can be selected.

Further, E. Goll, D. Hill and W. Severin
By "Modern Exposure Determination for Custumizing Ph
otofinishing Printer Response ", JAPE, 5,93-104 (1979)
In the chromaticity calculated based on the density of the original picture, since the color temperature of the photographing illumination significantly affects a specific hue, there is a method of determining the exposure amount that adjusts the collection level depending on the hue. Although it is shown, it is necessary to adjust the density which is the standard of the low-ward collection in order to obtain a photographic print with proper color balance.

Usually, in a photographic printing apparatus of the LATD control system, changes in the densities of the B, G, and R colors of the original image are caused by the difference between the characteristics of the photographic film and the color distribution of the subject. Can not be identified automatically. For this reason, various exposure conditions such as the reference density for color correction as described above are preset for each type of photographic film, and the reference exposure condition set according to the type of photographic film to be printed is selected. There is. However, setting this standard exposure condition requires a great deal of effort because trial and error of trial exposure and inspection of the obtained photographic prints are repeated, and it is an important step that influences the quality of all photographic prints. Therefore, it requires skill and high skill.

On the other hand, in recent years, high-sensitivity films, films for different purposes, or new films with various improvements have been released each year by each manufacturer, and the number of film types has increased to tens. ing. Therefore, there is a demand for a method of giving appropriate exposure conditions to individual original images from one reference exposure condition regardless of the characteristics of each type of photographic film.

In response to such a demand, among measurement values obtained by color separation scanning a color photographic film, a pixel belonging to a predetermined chromaticity region, for example, a region having low saturation is selected, and the selected pixel is selected. Proposals have been made to determine the exposure dose based on measured values.

For example, in JP-A-59-220760, the chromaticity of each measurement point is obtained with reference to the lowest density (including mask density) in the original image of the photographic film or its periphery, and the neutral density of each measurement point is determined. A method is disclosed in which the limit value of chromaticity is expanded with an increase in the, and a measurement point that does not exceed the limit value is selected. This example further describes that it is preferable to have a fan-shaped value that is divided into four regions on the chromaticity plane as the hue limit value.

[0013]

In the above-mentioned conventional example, the adjustment value of the exposure amount (for example, the collection level at the time of low-word correction) is set in multiple stages according to the hue, and those values are stored in the RAM / ROM or the like. Because it is stored in memory,
It was necessary to secure a large memory capacity. Further, since the hue stages are subdivided, a great deal of labor is required when determining the collection level value of each hue.

In addition, depending on the finish quality of the photographic print,
If you want to change the exposure adjustment value for a specific hue, or if you want to change the exposure adjustment value for a specific hue according to the frequency distribution of shooting scenes due to regional differences or seasonal differences, It took a lot of work to reset the values for some hues around and around it, and to confirm that it had an effect on the desired hue and did not adversely affect other hues.

Furthermore, the above-mentioned JP-A-59-2207.
In the method of No. 60, the adjustment value of the exposure amount according to the hue is set by the discontinuous value on the chromaticity coordinate. Therefore, for an original image having a hue in the boundary area, the exposure value adjustment value fluctuates greatly due to subtle differences in the photometric conditions, and the copy reproducibility of the same original image is reduced, or the finish of almost the same scene is unsatisfactory. It had the drawback of being continuous.

In view of the above points, the present invention can simplify the setting of the exposure amount adjustment value for the hue, reduce the storage amount related to the set value, and maintain the continuity of the adjustment values of the adjacent hues. However, it is an object of the present invention to provide a method for determining a photographic printing exposure amount, which can be automatically generated to stably produce a print with a good finish.

[0017]

To achieve the above object, the present invention is directed to color separation photometry of an original image on a color photographic film to calculate the hue of the original image, and to adjust the exposure amount corresponding to the hue of the original image. The value is obtained by interpolating an exposure amount adjustment value set in advance for a specific hue, and the exposure amount of each color for the original image is determined based on the obtained exposure amount adjustment value. This is to simplify the setting of the adjustment value and to reduce the storage amount related to the setting value.

Further, an exposure amount adjustment value for the hue of the original image is calculated in advance for all hues required for the interpolation calculation,
Obtained by selecting from the stored exposure amount adjustment values,
The calculation time for the interpolation can be omitted. Further, the hue of the original image is calculated based on the photometric value or the estimated value of the neutral color stored in advance, so that it is less susceptible to the fluctuation of the measurement system. The photometric value or estimated value of the neutral color is prestored according to the type of the photographic film, and the color center (origin of hue space) can be adjusted according to the characteristics of the film. Is.

[0019]

First, the exposure amount adjustment value for a specific hue selected appropriately such as B (blue), G (green), and R (red) is calculated in advance and stored in the memory (FIG. 8, FIG. 8). Step S
101).

Next, the original image of the color photographic film set in the scanning section is subjected to color separation photometry to scan and read the image information of the original image. The image information is statistically processed by an image processing unit to obtain an image characteristic value (average value), a reference value for chromaticity evaluation, chromaticity, etc., and a hue of an original image is calculated (step S102). .

Next, an exposure amount adjustment value corresponding to the hue of the original image is obtained by performing an interpolation operation from the exposure amount adjustment value of a specific hue (step S103). At this time, linear interpolation or spline interpolation is used for the interpolation calculation.

In accordance with the exposure amount adjustment value of the original image thus obtained, the exposure amount under the LATD control is appropriately corrected to determine the final printing exposure amount for each color of the original image (step S104).

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The photographic image information processing method of the present invention will be described below with reference to the embodiments shown in the drawings. Although the present invention can be applied to a color copying machine or the like, the case of being applied to a photo printing apparatus will be described here as an example.

(Structure of Photographic Film) FIG.
1 shows the structure of a 135 photographic film that has been subjected to development processing. In the figure, a photographic film F on which a developed original image (group) I is formed is spliced by a splice 10 to form a roll. In the rolled photographic film F, a notch (group) 12 indicating the center position of the original image is arranged at the side edge portion in the notch step before the photographic printing step. By detecting the notch 12, conveyance control such as positioning of the photographic film F in the subsequent steps is performed. As shown in the figure, the photographic film F is provided with an identification code (for example, a DX code) 14 indicating its type. Also,
Well-known perforations (group) P are arranged in advance on this side edge portion. The photographic film F in this example is 1
It is needless to say that the photographic film is not limited to the 35 photographic film, and may be another photographic film (for example, 110 film). The roll-shaped photographic film F processed in this way is printed in a photographic printing apparatus.

(Regarding the Structure of the Photographic Printing Apparatus) In FIG. 2 showing the structure of the photographic printing apparatus, the photographic film F is set on the spool 20 and wound on the spool 21 via a predetermined transport path. A scanning unit 22 is provided in the middle of the path, by which the original image recorded on the photographic film F is separated into B, G, and R colors and scanned.

The scanning unit 22 has a photographic film F.
A well-known one-dimensional CCD that performs main scanning in the width direction of each color is provided for each color, and scanning is performed by these, and the obtained image signal of each color of B, G, and R is supplied to the image processing unit 24. . Further, the notch 12, the splice portion 10, and the identification code 14 provided on the photographic film F are detected by the detector K, and the detection signal thereof is supplied to the transport control portion 23.
The conveyance control unit 23 processes the detection signal and outputs an image processing unit 24 as a notch signal, a splice signal, and an identification code signal.
And the photographic film F by driving the pulse motor 75 while sending it to the information processing unit 26 via the system bus 74.
Control the transportation of. Further, the carrier pulse at this time is used as a synchronization signal at the time of sampling the image signal, and the image processing unit 2
No. 4, and sub-scanning is performed accordingly.

In the image processing section 24, the image signal supplied from the scanning section 22 is amplified, sampled and held, and A
/ D converted. Further, a drive signal for driving the CCD of the scanning unit 22 is sent to the image processing unit 24,
A timing control circuit (not shown) for controlling the sampling timing is provided. The A / D-converted image signal is converted into a density value via a LUT (look-up table) composed of a ROM or the like, and then is subjected to appropriate rounding processing in both the main scanning direction and the sub-scanning direction. Shaped by As a result, two-dimensional image density information (hereinafter, simply referred to as image information) consisting of a predetermined number of pixels (for example, 16 × 16 pixels) is finally obtained regardless of the format of the photographic film F, and this information is information. It is sent to the processing unit 26.

The image signals of B, G, and R colors obtained by the scanning unit 22 in this manner are sent to the image processing unit 24, A / D converted and shaped into image information of a predetermined format, and then the information. It is sent to the processing unit 26. Therefore, the information processing unit 2
6, the common processing can be performed regardless of the format of the photographic film F.

The image information is subjected to a series of information processing, which will be described later, in the information processing section 26. As a result, the exposure amount for each original image is calculated, and the signal of this exposure amount is exposure controlled through the communication line 28. It is transmitted to the unit 30. The photographic film F that has passed through the scanning unit 22 absorbs the difference in the transport speed of the photographic film F between the scanning unit 22 and the exposure unit 32, and at the same time, prescans a plurality of original images before exposure. It is sent to the exposure unit 32 through the buffer unit 34 provided. The transport path between the scanning unit 22 and the exposure unit 32 has a length corresponding to a maximum of 24 sheets of 135 photographic film.
Image information corresponding to almost all original images I recorded on one piece of photographic film 5 can be obtained prior to exposure.

Each original image formed on the photographic film F is positioned in the exposure section 32, and the light emitted from the light source 36 is illuminated by the diffusion section 38 as uniformized light.
Further, the lens 54 optically forms an image on the photographic printing paper 40 and exposes it.

At this time, the photometric filters 4 for each of B, G, and R colors
The average transmitted light of each color of B, G, and R of the original image passes through the photodiodes 44a, 44b, and 44c through 2a, 42b, and 42c.
Is received by. This received light amount is photoelectrically converted into B,
The photometric signals of the G and R colors are supplied to the exposure control unit 30, further A / D converted, and the exposure amount is calculated based on the data obtained as a result and the correction amount supplied from the information processing unit 26. Be seen.

In the exposure control section 30, the exposure amount is set to the yellow (Y), magenta (M), and cyan (C) filters 50a, 50 arranged above the exposure section 32.
b, 50c and the driving condition of the shutter 52 arranged below the exposure unit 32 are converted. The filters 50a, 50b, 50c and the shutter 5 are selected according to the driving conditions.
2 is inserted in the exposure optical path to adjust the exposure given to the photosensitive layers of the respective colors of the photographic printing paper 40. After the completion of this exposure, the photographic printing paper 40 is transported by a predetermined distance in preparation for the next exposure, and the photographic film F is transported to position the original image I to be printed next in the exposure section 32.

(Regarding Configuration of Information Processing Unit) In the detailed configuration diagram of the information processing unit of FIG. 3, image information Di (X, Y) of each color of B, G and R sent from the image processing unit 24.
(I: B, G, R, and so on) is stored in the memory 102 via the system bus 74. The CPU 104 reads out the image information stored in the memory 102 and calculates the exposure amount for each original image I formed on the photographic film F.

The exposure amount obtained here is the communication line 28.
Through the exposure control unit 30. The notch signal, the splice signal, and the identification code signal sent from the transport control unit 23 via the system bus 74 are also stored in the memory 102 and processed by the CPU 104.

The auxiliary storage unit 106 stores information to be saved, constants necessary for processing, and the like. The auxiliary storage unit 106
Is composed of, for example, a magnetic disk, and the recording information can be taken out to the outside as needed.
This not only allows you to store information for a long time,
The information can be saved even when the power is cut off, the information saved by an external independent device can be processed, and constants and the like can be initialized and changed. The film unique information described later is stored in the auxiliary storage unit 106, and is loaded into the memory 102 as needed. Further, 108 is a keyboard for various operations, and 112 is a display device, which is configured to be able to perform input / output through the interface circuit 110.

(Regarding internal processing in the information processing section)
Hereinafter, the image information processing in the information processing unit 26 will be described in detail. The statistical amount of image information obtained from a plurality of original images I recorded on the photographic film F is effective as film-specific information indicating the characteristics of this film. In this embodiment, the case where the cumulative density function CDF _i (D) is used as such a statistic will be described. From the cumulative density function CDF _i (D) is the frequency of the image information FRQ _i (D), is obtained by the following expression (1).

It should be noted that this cumulative density function can be simply added, and if added according to the film type group over a plurality of original images according to the following equation (2), the accumulated information MCDF
_ij is obtained. Here, MCDF _{ij, -1} (D) indicates pre-stored information, j indicates a film type group, and so on. MCDF _ij (D) = CDF _i (D) + MCDF _{ij, -1} (D) (2)

In this way, the cumulative density function is obtained from the plurality of original images recorded on the photographic film. The cumulative density function MCDF _ij (D) has a close correlation with the tone reproduction characteristic of the photographic film. It has been confirmed by experiments that the image density of each color giving a predetermined value to this cumulative density function is extremely effective as an estimation of the neutral color recorded on this photographic film.

The film-specific information is 1 for the film.
The short-term storage information required for each book, the long-term storage information obtained for a plurality of films of the same product type or product group, and the like are conceivable. Here, the process when using the long-term storage information will be described.

FIG. 4 is a flow chart showing an example of the flow of processing according to the present invention. In step S1, the product type group is determined from the identification code signal sent from the transport control unit 23. FIG. 5 shows an example of the correspondence relationship between the identification code and the product group. As shown in FIG. 5, a product type group is individually assigned to each identification code, but this product type group may be common to the identification codes. As a result, the number of product groups can be limited and the storage amount of long-term accumulated information can be adjusted according to the data storage area.

If the identification code cannot be read or the product group corresponding to the read identification code cannot be determined, a predetermined product group is automatically set (see FIG. 5). The default corresponds to such cases). As shown in the table of FIG. 5, a method of assigning an exceptional product group to the default (corresponding to 0 in FIG. 5), a method of assigning a standard product group (corresponding to 1 in FIG. 5), etc. is there.
As a result, it is possible to automatically deal with an exceptional situation in which the identification code cannot be read or the product type group corresponding to the read identification code cannot be determined.
Of course, in such a case, an alarm or the like may be issued to artificially specify the identification code or the product type group.

When the product group is determined, step S
In 2, the long-term accumulated information corresponding to this product type group is loaded from the auxiliary storage unit 106 to the memory 102.
In addition, the representative value for each product group is stored in the auxiliary storage unit 106 in advance as an initial value of the long-term storage information.

Further, in step S3, the scanning unit 2
2, the color separation scanning is performed, the image processing unit 24 shapes the image, and the image information sent to the information processing unit 26 stores the image information.
Memorized in. In step S4, the average value AVE _i of the image information is calculated as the image characteristic value. Then step S
In 5, the long-term accumulated information is referred to by this average value, and the reference value of chromaticity evaluation for this image information is obtained as follows.

In the following, M _i is a reference value for chromaticity evaluation obtained by referring to the cumulative density function of long-term accumulated information P is a cumulative density function (MCDF) value with respect to the average value of the green image information of the original image .

First, the cumulative density function value corresponding to the average value of the green image information of the original image is obtained from the long-term accumulated information according to the equation (3), and the cumulative density function for each color is reversed according to the equation (4). The reference value for chromaticity evaluation is obtained by referring to. P = MCDF _G (AVE _G ) (3) M _i = MCDF _i -1 (P) (4)

FIG. 6 schematically shows the method of referring to this cumulative density function. As is clear from the equation (1) and FIG. 6, since the cumulative density function is continuous at any point and is a monotonically increasing function, the inverse function as described above can be obtained very easily, and an exception There is an advantage that no processing is required.

The cumulative density function is related to the tone reproduction characteristic of the film, and the image information giving a constant value to the cumulative density function is
It is known to correspond to neutral color information according to the characteristics of the film. As described above, in the present invention, the film-specific information is referred to according to the image characteristic value of the original image, and the reference value for chromaticity evaluation is dynamically determined.

Next, in step S6, the chromaticity (x, y) relating to the original image is evaluated as follows based on the reference value of this chromaticity evaluation (see the flowchart of FIG. 8). _{D 'i = AVE i - M} i ··· (5) x = D' B × 3 1/2 / 2 - D 'R × 3 1/2 / 2 y = D' B / 2 - D'G + D' _R / 2 (6)

Further, in step S7 (step S102 in FIG. 8), the orthogonal coordinate system (x, y) is converted into the polar coordinate system (S, H) according to the following equation (7). In addition,
S indicates saturation and H indicates hue. S = (x ² + y ² ) ^1/2 H = tan ^-1 (y / x) (7) where D' _i is when the subject recorded in the original image is a neutral color. Takes a small value and takes a large value when the color distribution of the subject is biased. Therefore, by using this value, the exposure correction can be selectively applied to the color ferria.

In step 8, for the hue H obtained in the previous step, the exposure amount for the original image is determined based on the exposure amount adjustment value input in advance for the specific hue.
Below, as an example of the exposure amount adjustment value, a collection level at the time of performing low-row correction will be described.

In this case, the standard lowward rate is set in advance for a certain specific hue, for example, each of the B, G, R, and Y color ferria areas and the tungsten light source area (FIG. 7). (FIG. 8, step S1
01). In general, this lowward rate is set to a small collection level (a value close to no collection) in order to enhance the lowward effect for the hue of the color ferria.
In addition, regarding the hue of the tungsten light source, the collection level is large (value close to full collection).
It is desirable to set each.

Since the hue of each original image is calculated in the above-described process (step S102), the lowward rate for it is automatically calculated by appropriately interpolating the intermediate position based on the lowward rate of these specific hues. Are set (step S103 in FIG. 8). As the interpolation method, there are a linear interpolation method as shown in FIG. 9 and a spline interpolation method as shown in FIG.

For example, in the case of the linear interpolation shown in FIG. 9, it is assumed that the collection level is 100% (that is, full correction, lowward rate = 0%) in the tungsten light source area, and the correction level is set in the R (red) color area. When it is set to 40% (lowward rate = 60%), the hue of the intermediate area is on the straight line connecting the two in the hue space,
Interpolation can be performed using the minutiae.

It is also possible to perform spline interpolation with a multi-dimensional curve as shown in FIG. In this figure, when the finish of the photographic print is inspected, since the human inspection sensitivity to the chromaticity of the complementary colors of B, G, and R3 primary colors is high, the complementary colors Y, M, and
An example is shown in which the collection level for each color ferria region of C is set relatively small and interpolation is performed.

In these examples, only the collection level value corresponding to a specific hue is stored in the memory 102, and the collection level of the hue of the original image is calculated and set by an interpolation formula each time, so the memory amount is minimized. It is designed to be held to the limit. Here, the sample hue corresponding to the hue of the original image is set at appropriate intervals in the hue space, and the interpolation calculation value of the exposure amount adjustment value for these sample hues is set in the memory 102 in advance, thereby omitting the interpolation calculation. The processing time may be shortened.

Next, step S9 (step S9 in FIG. 8).
At 104), the exposure amount for photographic printing is determined based on the equation (8). _{E i = LATD i - LATD 0i} + αD 'i + βND + E 0i (8)

Here, E _i is the exposure amount of each color of B, G, and R (logarithmic value of exposure time), and LATD _i is used for printing provided by the photodiodes 44a, 44b, and 44c in the exposure unit 32. The average transmission photometric value (logarithm) from the original image I, LATD _0i is the average transmission photometric value (logarithm) from the standard original image, D' _i is the color correction value transmitted from the information processing unit 26, and α is the intensity of color correction. A coefficient for adjustment, ND is a density correction value transmitted from the information processing unit 26, β is a coefficient for adjusting the strength of density correction, and E _0i is the exposure amount (exposure time of the exposure time) set for the standard original image. Logarithmic value), i is B,
These are G and R colors. The exposure amount thus obtained is transmitted from the information processing unit 26 to the exposure control unit 30.

Next, in step S10, the image information D _i
Is added to the stored information MCDF _ij (D) using the equations (1) and (2). In step S11, it is determined whether or not the processing for all the original images to be exposed on the film is completed, and if not completed, the exposure amount for each image on the film is sequentially determined. In step S12, it is determined whether or not the exposure processing for all the films to be processed is completed, and the above-described film processing is repeated for the next film.

As described above, in this embodiment, the case where the long-term accumulated information is used as the film-specific information has been described. However, the short-term accumulated information of the image information obtained by previously scanning a plurality of original images in the same film is replaced with the long-term accumulated information. It is also possible to use. In this case, the chromaticity of each pixel can be evaluated in accordance with the characteristics of each film, which varies depending on the storage conditions.

Further, the long-term accumulated information and the short-term accumulated information may be combined to form new accumulated information. In this case, it is possible to evaluate the chromaticity comprehensively corresponding to the characteristics of each film, which varies depending on the characteristics of each film type, the developing characteristics, and the storage conditions.

Further, in the present embodiment, the case where the average value of the image information is used as the image characteristic value has been described. However, the information of each pixel is used as the image characteristic value, and the film specific information is referred to for each pixel to evaluate the chromaticity. The reference value of may be obtained. In this case, although the processing time becomes long because the number of times the film-specific information is referred to increases, the reference value for chromaticity evaluation can be obtained more accurately. Further, as an intermediate method between the two methods, the film specific information is referred to by the characteristic value of the pixel set composed of a plurality of pixels, and the reference value of the chromaticity evaluation for the pixels belonging to this set is obtained for each set. Good.

Further, in this embodiment, the case where the exposure amount is directly obtained from the information of the pixels classified based on the evaluation of the chromaticity has been described, but the accumulated information is processed according to the result of this classification, and the accumulated information is accumulated. It goes without saying that the information of the classified pixels may be indirectly used as the reference value for color correction when the exposure amount is determined by referring to the information.

[0063]

As described above, according to the present invention, an original image on a color photographic film is subjected to color separation photometry to calculate a hue of the original image, and an exposure amount adjustment value corresponding to the hue of the original image is set to a specific hue. On the other hand, it is characterized by interpolating a preset exposure amount adjustment value and determining the exposure amount of each color for the original image based on the obtained exposure amount adjustment value. It is possible to simplify the setting and reduce the storage amount related to the set value.

Further, an exposure amount adjustment value for the hue of the original image is calculated in advance for all hues required for the interpolation calculation,
Since it is obtained by selecting from the stored exposure amount adjustment values, the exposure amount adjustment value of the original image can be quickly obtained by omitting the calculation time related to interpolation. Further, since the hue of the original image is calculated based on the photometric value or estimated value of the neutral color stored in advance, it is possible to reduce the influence of fluctuation of the measurement system. Further, since the photometric value or estimated value of the neutral color is prestored according to the type of the photographic film, it is possible to adjust the color center (origin of hue space) according to the characteristics of the film. can do.

As a result, the exposure amount adjustment value for the hue is simple, the amount of memory relating to the set value can be reduced, and the adjustment values for the adjacent hues are automatically generated while maintaining their continuity, resulting in a good finish. It has an excellent effect of providing a method for determining a photographic printing exposure amount capable of stably producing a printed image.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a color photographic film in a scanning reading unit.

FIG. 2 is an overall configuration diagram of a photographic printing exposure apparatus.

FIG. 3 is a block diagram showing a control unit of the photographic printing exposure apparatus.

FIG. 4 is a flowchart showing internal processing in the information processing unit.

FIG. 5 is an example of a map showing a correspondence relationship between film identification codes and product type groups.

FIG. 6 is a schematic diagram showing a method of referring to a cumulative density function.

FIG. 7 is a distribution diagram showing a color ferria in a hue space.

FIG. 8 is a flowchart for determining a printing exposure amount of an original image.

FIG. 9 is a principle diagram of linear interpolation in a hue space.

FIG. 10 is a principle diagram of spline interpolation in a hue space.

[Explanation of symbols]

 22 Scanning Section 23 Transport Control Section 24 Image Processing Section 26 Information Processing Section 30 Exposure Control Section 32 Exposure Section 102 Memory 104 CPU F Color Photographic Film I Original Image

Claims (4)

[Claims] 1. An original image on a color photographic film is subjected to color separation photometry to calculate a hue of the original image, and an exposure amount adjustment value corresponding to the hue of the original image is set as an exposure amount preset for a specific hue. A method for determining a photographic printing exposure amount, characterized in that the exposure amount of each color with respect to the original image is determined on the basis of the exposure amount adjustment value obtained by interpolating the adjustment value. 2. The exposure amount adjustment value for the hue of the original image is calculated by selecting from the exposure amount adjustment values calculated and stored in advance for all the hues necessary for the interpolation calculation. 1. The method for determining the exposure amount for photographic printing according to 1. 3. The method for determining a photographic printing exposure amount according to claim 1, wherein the hue of the original image is calculated based on a photometric value or an estimated value of a neutral color stored in advance. 4. The photographic printing exposure amount determining method according to claim 3, wherein the photometric value or estimated value of the neutral color is stored in advance according to the type of the photographic film.