JP2502131B2 - Method for determining photoprint exposure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for determining a photographic printing exposure amount, and in particular, it is suitable for a film type having characteristics different from those of a reference film type based on the printing exposure conditions of the reference film type. The present invention relates to a method for determining a photographic printing exposure amount capable of automatically determining printing exposure conditions.

[Problems to be Solved by Prior Art and Invention]

The color negative is B (blue), G (green), R for the entire screen.
It is known empirically that the (red) three-color light is transmitted, but 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) However, logF is the logarithm of the amount of printing light, K is a constant, D is the negative integrated transmission density (LATD) measured by the photometric system, and j is B,
Any color light of G and R.

However, if the amount of printing light is controlled by the automatic printer based on the above formula (1), the print from the underexposure negative in which a gray object is photographed has a higher overall density than the print from the proper negative, and the exposure transient occurs. Prints from negatives have low density. For this reason, a slope control circuit is provided to correct the Dj in the equation (1) to determine the exposure amount. 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 (light source negatives) that have been photographed with light sources (fluorescent lamps, tungsten lamps, etc.) that are significantly different from daylight, and color On a negative or the like having a fair area, a defective print with an improper color balance is likely to occur. For this reason,
The exposure amount is determined by correcting (color collection) Di in the equation (1). At this time, an excessive correction with respect to the standard correction (normal correction) is called a high correction, and an excessive correction is called a lower correction.

However, in recent years, a large number of high-sensitivity films have been developed, and the number of types of films has increased to tens. However, the printing conditions of each film do not always match, and the condition setting film for setting the conditions of the automatic printer for each film is very limited. Usually, the film for this condition setting is
A negative in which a portion corresponding to the negative that photographed a yellowish green subject close to gray was placed around the portion corresponding to the negative that photographed the gray subject. Three types are available. Therefore, it is very difficult to set the exposure condition for various films without such condition setting film, which requires a long experience and a lot of time. Further, in order to maintain high quality, it is indispensable to control the exposure condition of each film type, but it is difficult to control if there are many film types. Therefore, it has been proposed to automatically determine an appropriate printing exposure condition for various films from one standard printing exposure condition.

It is known that for films that have changed over time and films with different characteristics (films with different characteristic curve shapes), it is easy to obtain proper prints by controlling the exposure amount with high correction and baking. The image quality of the image is not sufficient.

In addition, there is a known technology that determines the exposure condition of the film image to be printed by dividing the film screen into a number of photometers, analyzing each photometric data, correcting the standard printing exposure condition using the selected photometric data, and determining the exposure condition of the film image to be printed. (JP-A-51-94927, JP-A-52-20024, JP-A-59-220761,
JP-A-61-198144, etc.). According to this prior art,
If the photometric partial photosensitivity distribution of the photometric system of the automatic printer matches the spectral sensitivity distribution of the printing material with extremely high accuracy,
It is possible to print a plurality of types of films having different characteristics based on the exposure conditions of the reference film type.

By the way, when the spectral sensitivity distribution of the photometric system and the spectral sensitivity distribution of the exposure system match as described above, only when the three R, G, and B curves of the film characteristic curve are straight lines, It is possible to properly print and expose each film type depending on the printing and exposure conditions of the reference film type. Therefore, the above method has a problem that a good print image cannot be obtained in the exposure region corresponding to the non-linear portion of the characteristic curve. Regarding this non-linear portion, JP-A-49-29641 proposes an electric circuit for approximately linearly correcting the non-linear portion at the upper and lower ends of the film characteristic curve. However, in this case, since the non-linear portion is corrected to a straight line, a good print image cannot be obtained in the exposure area of the non-linear portion as described above.

The reason why a good print image cannot be obtained in the non-linear portion will be further described with reference to FIG. Standard film type 3
Assuming that the color characteristic curve is substantially the same as the G and R characteristic curves in FIG. 14, the gradation of the overexposed portion of the reference film type is softer than the gradation of the linear portion, so it is small. The slope control value is set. For this reason,
When printing is performed using a small slope control value as described above, the slope control value is too small for the B characteristics of the film to be printed, so the exposure amount to the blue sensitive layer of the photographic paper decreases and the yellow color The coloring of the material is reduced, the finished print tends to be bluish, and a good printed image cannot be obtained.

In the above description, the over-exposed portion has been explained, but also in the under-exposed portion, since the characteristic curve of B is deviated from the characteristic curve of the reference film type, similarly good printed image cannot be obtained. That is, if the density balance of the three colors of the film to be printed is different from the density balance of the R, G, and B colors of the reference film type, the color that has a complementary color relationship with the color that has a different density balance will not be displayed. Insufficient printing results in a poor printed image.

Further, a film having a gradation higher than that of the reference film or a film having a high mask density has a higher density than the reference film even in the overexposed portion. Therefore, the exposure time is long, and therefore, the influence of reciprocity law failure of the printing paper is greatly influenced. The reciprocity law failure is corrected by the over slope control function when determining the exposure conditions of the standard film. However, if the overexposed area has a higher density than the reference film, the slope control function cannot sufficiently correct the reciprocity law failure of the printing paper. Therefore, the print density of a color having a density higher than that of the reference film is insufficient in the overexposed portion, and a good printed image cannot be obtained.

The present invention has been made to solve the above problems, and corrects the difference in the density balance for film species having a difference in the density balance different from the density balance of the reference film species, and at the same time, in the high density portion of the film. An object of the present invention is to provide a method for determining a photographic printing exposure amount, which can obtain a good printing image by correcting the influence of reciprocity law failure of printing paper at the time of printing.

[Means for solving the problem]

In order to achieve the above object, the present invention obtains photometric data by dividing a whole or a part of a film image of a film to be printed into a large number and measuring the photometric data. In a method of determining a photographic printing exposure amount based on image density values of three colors obtained based on photometric data belonging to a color region, a film to be printed with respect to a density balance of three colors of a reference film type. The exposure amount is determined by correcting the printing exposure conditions of the reference film type for at least one selected color based on the difference in the density balance of the three colors.

In determining the exposure amount, a functional expression including an image density value of one color out of the image density values of three colors obtained from the photometric data belonging to the specific color area and a preset set density value is used. A color correction value for correcting a difference in density balance between a high density portion and a low density portion of a film to be printed is obtained for at least one color, and the exposure amount is determined by correcting the printing exposure condition of the reference film type. it can. It is effective to increase the color correction value from the medium density portion of the film to be printed to the high density portion or from the medium density portion to the low density portion.

This color correction value Aj can be obtained based on the following formula.

Aj = k1j (Dj-Daj) / (Dbj-Daj) + k2j (2) where j represents any one of R, G, and B, and Dj is obtained from the photometric data belonging to the specific color area. Image density values of j, Daj and Dbj are preset density values of j whose magnitude relationship is Dbj> Daj, and k1j and k2j are color correction values Aj including 0.
Is the coefficient of j that determines the magnitude of

Further, the color correction value Aj can be determined by an expression including Dj / Daj.

Further, the exposure amount can be determined by multiplying the image density value of the three colors or the value corresponding to the image density value by the reciprocal of the gradation of the three colors in the specific density range of the reference film type.

The density balance of the three colors of the reference film and the density balance of the three colors of the film to be printed can be determined from the gradation of the three colors of each film.

[Action]

In the present invention, the photometric data is obtained by dividing the entire surface or a part of the film image of the film to be printed into a large number and measuring the light. The exposure amount of the film to be printed is determined by the printing exposure conditions of the reference film type and the image density values of the three colors obtained based on the photometric data belonging to the specific color area. As the specific color area, a low chroma color area including a neutral color can be adopted. Also, 3
The image density value of a color can be obtained using only the photometric data belonging to this specific color area, but the representative value (photometric data other than the specific color area obtained from the photometric data of this specific color area is It may be used after being converted into, for example, an average value of three colors).

When the density balance of the three colors of the film to be printed is different from the density balance of the three colors of the reference film type, for at least one color selected based on the difference in the density balance (for example, the color having the largest difference), The exposure amount is obtained by correcting the printing exposure conditions of the reference film type.

To correct the exposure condition, use the color correction value obtained by the relational expression including the image density value of one color obtained from the photometric data belonging to the color area and the preset density value. You can It is effective to increase the color correction value from the medium density portion (normal density portion) of the film to be printed toward the high density portion or the low density portion. Normally, the difference in the density balance increases from the middle density part to the high density part or the low density part of the characteristic curve. Therefore, by increasing the color correction value according to the density as described above, the linear part of the characteristic curve It is possible to correct the difference in the density balance in the entire density range in which the density balance is different, without discontinuous color change, by reducing the correction effect in step 2. Further, even in the case of a straight line portion, the influence of reciprocity law failure of the printing paper, which is received in the higher density portion, can be corrected by increasing the color correction value according to the film density.

The color correction value Aj based on the relational expression using the difference between the image density value and the set density value is as follows.

Aj = k1j (Dj-Daj) / (Dbj-Daj) + k2j (2) where j represents any one of R, G, and B, and Dj is obtained from the photometric data belonging to the specific color area. Image density values of j, Daj and Dbj are preset density values of j whose magnitude relationship is Dbj> Daj, and k1j and k2j are color correction values Aj including 0.
Is the coefficient of j that determines the magnitude of For example, 0 ≦ k1j
≦ 2.0, 0 ≦ k2j ≦ 2.0 or 0 ≦ k1j ≦ 200, 0 ≦ k2j ≦ 20
It is a value such as 0.

It is possible to use the density value of the overexposed image of the condition setting film of the reference film type as the set density value Dbj, and use the density value of the normal exposure image of the condition setting film of the reference film type as the set density value Daj. As described above, in addition to the difference Dj-Daj between the image density value of one color and the preset density value, the ratio Dj / Daj is used and the color correction value Aj is determined with the set density value Daj as the normal density value. You can

On the other hand, in the case of printing a reference film type or a film having characteristics similar to the reference film type, in order to make the correction effect by the above color correction value zero or very small, a specific density range of the reference film type (for example, , And the reciprocal of the gradient of the three colors in the medium density range) is multiplied by the image density value of the three colors or the value corresponding to the density. As a result, when a reference film type or a film type having characteristics similar to the reference film type is printed, color deviation is zero or extremely due to the above conversion of the image density value obtained from the photometric data of the specific color region. It will be small, and will be slightly affected by the color correction value.

〔The invention's effect〕

As described above, according to the present invention, since the difference in the density balance of the three colors of the film to be printed with respect to the density balance of the three colors of the reference film is corrected, the characteristic curve of one color of the film to be printed is corrected. Is relatively high on the high density side with respect to the characteristic curve of the reference film (when the gradation is hard), the effect of reciprocity law failure of the printing paper is corrected and the exposure amount of this one color is When the exposure amount of two colors is increased so that the color balance is controlled to match, and conversely, the characteristic curve of one color is relatively lower than the characteristic curve of the reference film (when the gradation is soft) ), The effect due to the non-linearity of the film characteristic curve is corrected
The exposure amount of each color is controlled to be smaller than the exposure amounts of the other two colors, and the color balance is controlled so as to match with each other, so that an excellent color balance can be obtained.

Further, if the color correction value is determined by the functional expression of the difference or ratio between the image density value and the preset density value, and the correction effect by the color correction value becomes larger as the density becomes higher, no correction is required. The effect of reducing the correction effect in the straight line portion of the characteristic curve of the film and increasing the correction effect in the high density non-linear portion, and preventing abrupt color change can be obtained. In addition, the effect of reciprocity law failure of photographic paper, which cannot be corrected by the slope control in the density higher than the high density portion of the reference film, can be corrected without abrupt color change.

Then, by multiplying the image density value and the like by the reciprocal of the gradation value of the reference film type, the color correction value is set based on the density balance from low density to high density with respect to the nonlinearity of the characteristic curve in the reference film type. By removing the correction effect or making it extremely small and optimizing the slope control value, it is possible to obtain the effect that the color and density can be properly set and used as the reference exposure condition.

〔Example〕

A color-added automatic color photographic printing apparatus to which the present invention is applicable will be described below with reference to the drawings. As shown in FIG. 1, a lamp box 10 having a mirror box 18 and a halogen lamp is sequentially arranged below the negative film 20 loaded in the negative carrier and conveyed to the printing section.
A motor is installed between the mirror box 18 and the lamp house 10.
A rotary disk 14 rotated by 16 and an infrared cut filter 12 are inserted.

As shown in FIG. 2, the rotary disk 14 is provided with a color separation filter consisting of a G filter 15, a B filter 17 and an R filter 19 near its circumference. As shown in FIG. 3, the G filter 15, the B filter 17, and the R filter 19 are a white glass 23 coated with a dielectric multilayer film 25 and a colored glass 21 of any one of R, G, and B. And are arranged in parallel. Figure 4 shows a colored glass filter (R-64 filter manufactured by Hoya Glass Co., Ltd.) 21 and a dielectric multilayer film 25.
And R form a short wavelength of R, and the thermally stable infrared cut filter 12 forms a long wavelength of R.

Above the negative film 20, a lens 22, a black shutter 24, and a color paper 26 are arranged in order.The infrared cut filter 12, the filter on the rotary disk 14, the mirror box 18, and the negative film 20 are irradiated by the lamp house 10. The light beam transmitted through the lens 22 is configured to be imaged on the color paper 26 by the lens 22.

A two-dimensional image sensor 28 is arranged in a direction inclined 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. The two-dimensional image sensor 28 is a storage photoelectric conversion element such as CCD or MOS, an optical system for forming an image of the negative film 20 on the photoelectric conversion element, and a photoelectric conversion element output to process and output as image information. And a signal processing circuit for doing so. This image sensor 28
The photoelectric conversion element of R divides the negative image into a large number of pixels by dividing it into R,
The G and B3 primary colors are measured, and the signal processing circuit converts the output of the photoelectric conversion element into a digital signal and then performs the logarithmic conversion of the reciprocal of the output to output it as a density signal.

The characteristics of the infrared cut filter 12 are as shown by the one-dot chain line in FIG. 5 (3), and the relative spectral transmittance of the three-color photolytic filter for rotary disk is as shown by the solid line in FIG. 5 (3). . Further, the relative spectral sensitivity distribution of the two-dimensional image sensor 28 is as shown by the solid line in FIG. 5 (2), and the spectral sensitivity distribution of the two-dimensional image sensor 28 in the color addition method is the fifth.
It becomes as shown by the broken line in FIG. The relative spectral sensitivity distribution of color paper is as shown by the solid line in FIG. 5 (1), and the spectral sensitivity distribution of color paper in the color addition method is as shown by the broken line in FIG. 5 (1).

The two-dimensional image sensor 28, as shown in FIG.
Photometric value memory that stores each density signal (photometric data) of B
Connected to 30. The photometric value memory 30 is connected to the film-based density storage memory 32 and the photometric value selecting means 38. The film concentration storage memory 32 has a film classification means.
34 is connected, and the film-based density accumulation memory 32 is connected to the photometric value selecting means 38 via the film characteristic determining means 36. The photometric value selecting means 38 is connected to the exposure amount determining means 44 via the exposure control value calculating means 40. A print condition input means 46 is connected to the exposure amount determining means 44 via a print condition memory 48. The exposure amount determining means 44 controls the motor 16 to rotate the rotary disk 14 to control the exposure amount.

The operation of this embodiment will be described below while explaining each of the blocks shown in FIG.

The film classifying means 34 is a means for identifying a series of films and classifying the films with other films. Manufacturer, color material, γ
Negative films having some common values, base density, photosensitivity, characteristic curve shape, etc. are classified as the same film type for each film. The film classifying means 34 can use a DX code reading device for reading the DX code previously exposed on the side edge of the negative film. Since this DX code is a bar code that displays information indicating the film manufacturer such as the film manufacturer and the film type, it is possible to detect the film type by using the DX code reading device, and thus the Films to be attached can be classified by film type (film type) having the same or similar characteristics. It is also possible to classify the films by type using a device that reads the characteristics of the coloring material used in the film by detecting the peak value of the transmission density with respect to the characteristic wavelength of the negative film. Also, the film classification means
34 may be composed of a keyboard, and the film types may be classified by the operator's judgment and manually input. Further, it may be a means that only detects the beginning and the end of one film and detects that it is a series of films.

Print condition input means 46 and print condition memory 48
Is a standard film type, for example, R, G, B print conditions (printing exposure conditions) of Super HR100 (manufactured by Fuji Photo Film Co., Ltd.) are input and stored. At least one of the exposure amount, the exposure time, the filter amount, the light source brightness, the light source voltage, and the slope control value can be used as the printing condition. It should be noted that the condition setting film is used to set the printing exposure conditions.

The film-based concentration accumulation memory 32 is used as a film classification means 34.
Photometric memory for each film type sorted by 30
Output is stored and stored. For example, Japanese Patent Laid-Open No. 61-267
The technique described in Japanese Patent No. 749 can be used.
That is, the average negative density is obtained and stored by accumulating the densities of each photometric point, each screen portion, or the entire screen to obtain an average value. Alternatively, the output of the photometric value memory 30 may be accumulated and stored only for a series of films.

The film characteristic determining means 36 determines the characteristic of the film according to the R, G, and B densities stored in the film-based concentration accumulation memory 32. Hereinafter, an example in which the gradient (γ value) of the film characteristic curve is used as the film characteristic will be described. First, the R, G, and R stored in the film-based density storage memory 32 with respect to a reference value (for example, G density or average density of R, G, B (R + G + B) / 3, etc.)
The characteristic curve of the film is obtained for each of R, G, and B by obtaining the ratio of B concentration. FIG. 6 (1) shows a characteristic curve of R concentration with respect to G concentration, and FIG. 6 (2) shows a characteristic curve of R concentration with respect to (R + G + B) / 3 concentration.

To determine the film characteristic from these characteristic curves, for example, the gradient γ _{u of the} underexposed portion and the gradient γ _{o of the} overexposed portion can be used as shown in FIG. 7 (1). Further, the average value of the gradients (γ1 + γ2 + γ3) / 3 as shown in FIG. 7 (2) or the gradients γ1 and γ2 shown in FIG. 7 (3) can be used. In the above, the film-based density accumulation memory 32 and the film characteristic determination means 36
Although the method for automatically obtaining the film characteristic has been described by using, the both means are omitted and the film characteristic is previously stored in the film (film characteristic memory means), and the film classifying means reads out the film characteristic memory means from the photometric value selecting means. You may type in 38.

The photometric value selecting means 38 selects the photometric value used for the exposure control density value calculation according to the film characteristic, and the difference R between R and G is determined according to the film characteristic determined by the film characteristic determining means 36. '-G', the difference G'between G and B
A photometric value belonging to a specific color area assumed on a color coordinate centering on -B ', for example, a color area including a neutral color (gray) and a skin color is selected from the photometric value memory. A method for extracting data corresponding to the specific color area will be described below. First, a curve shown in FIG. 8 is obtained by using the densities R ₀ , G ₀ , B ₀ of three colors of an average negative film, and the average densities D ₀ = (R ₀ + G ₀ + B ₀ ) / 3 of three colors.
Create for each of R ₀ , G ₀ , and B ₀ . Further, in order to extract the data of the area close to the specific color area, the offset amounts d ₁₁ , d ₁₂ , d ₂₁ , d ₂₂ , d ₃₁ , d ₃₂ of the straight line are underexposed, normal exposed, and overexposed, respectively. And the area shown by the broken line in FIG. 8 is defined. Then, the average value D = (R + G + B) / 3 of the photometric values R, G, B is obtained, and it is determined whether or not the photometric value R for the average value D is included in the area shown by the broken line in FIG. . Similarly, the photometric values G and B
It is determined whether or not is included in the area shown by the broken line in FIG. All of the three photometric values R, G, B are the eighth with respect to the average negative film densities R ₀ , G ₀ , B ₀ .
The photometric value is selected and used for the exposure control density value calculation only when it is included in the area defined as shown in the figure. Of the photometric values R, G, and B, the photometric values not included in the above area are not used for the exposure control density value calculation, or the average value of the photometric values R, G, and B, the broken line in FIG. It is converted into an average value of photometric values belonging to the area indicated by and is commonly used for the exposure control density values of the three colors. Further, the above-described offset amount d ₁₁ to d ₃₂ is changed by the film species or gradient _{R 0 / D 0, G 0} / D 0, B 0 / D 0 is preferable.

The measurement value may be selected as follows. That is, the characteristic curves described with reference to FIG. 8 for the average negative film densities R ₀ , G ₀ and B ₀ are determined as shown in FIG. 9, and the photometric values R, G and B are determined using this characteristic curve. -27352, convert it to D ₀ by the method as shown in Japanese Patent Publication No.
Find G'and B '. By this conversion, the photometric values having the same color balance as the average negative film have the same R ',
It is converted into the density of G'and B '. And this R ',
It is determined whether or not G'and B'are used for the exposure control density value calculation on the chromaticity diagram. Incidentally, in selecting the photometric value used for the density value calculation for exposure control, even if selective weighting of the photometric value described in JP-A-61-198144 and JP-A-61-223731 is performed. Good.

The exposure control value calculation means 40 is a photometric value selection means 38.
The density value for exposure control is calculated using the photometric value selected in 1.
The exposure control density value is calculated from the density values obtained by classifying the photometric values according to the method described in JP-A-223731 and JP-A-61-232442. That is, in the photometric value selection means 38, as shown in FIG.
At 0, the density value for each pixel is normalized by setting the point corresponding to the specific color area as the origin. Next Step 102
In R, R'-G ', G'-B' are calculated using the normalized density values R ', G', B '. Next Step 104
In, a color area as shown in FIG. 11 is determined for each measurement point (each pixel) from the color coordinate table. Then, the color of the closed area on the color coordinate including the neutral color or the flesh color, or the color of the closed area on the color coordinate including the neutral color and the flesh color (for example, 0 (neutral color in FIG. 11), Areas of 1 and 3 (skin color))
A measurement point belonging to the area is selected (the above is performed by the measurement value selection means). And exposure control value calculation means
At 40, the density values of the selected measurement points before normalization are added to obtain the average value of R, G, and B, and this average value is used as the exposure control density value. Since this exposure control density value does not include a density value that causes a color area, it can be used for determining the exposure amount without lowering the degree of color correction.

The exposure amount determining means 44 determines the exposure amount of the film to be printed using the print conditions of the reference film type stored in the print condition memory 48 and the exposure control density value calculated by the exposure control value calculating means 40. For example, the exposure amount is calculated according to the following equation (9).

The calculation formula of the exposure amount will be described. The normal densities (corresponding to the printing and exposure conditions of the reference film type) for setting the printing conditions of the R, G, and B colors of the reference film type are respectively RN and G.
Let N, BN, and the negative values to be printed R, G, and B for each of the three colors for exposure control be DR, DG, and DB, respectively.
The exposure amounts er, eg, and eb of G and B for each of the three colors are expressed as follows.

Here, dR = DR-RN, dG = DG-GN, dB = DB-BN, and X11 to X33 are coefficients represented by the following expressions.

However, SC, SM, and SY are slope control values for R, G, and B respectively, and when dR> 0, dG> 0, and dB> 0, SC = SCO, SM = SMO, SY = SYO (where O is Representing an over rope), dR <0, dG <0, dB <0 SC = SC
U, SM = SMU, SY = SYU (where U represents underslope). Further, A _R , A _G , and A _B (represented by Aj as a general formula) are R, G, and B color correction values (color collection), respectively.

Next, expand equation (3) above and substitute equation (4),
By transforming the above equation (3) with (dR + dG + dB) / 3 = dW, the following equation (5) is obtained.

Here, when Aj = 1.0, the normal collection, Aj>
When 1.0, it means high collection, and when Aj <1.0, it means low collection, and in this embodiment, this color collection Aj (A _R , A _G , A _B ) is defined as shown in the following formula.

However, when 0 ≦ K11, K12, K13 ≦ 2.0, 0 ≦ K21, K22, K23 ≦ 2.0 and DR <RN, A _R = K21, when DG <GN, A _G = K22, DB <BN
In this case, A _B = K23, and RO, GO, and BO are over-density values for setting conditions of the reference film. When K11 = 0.5 and K21 = 1.0, A _R is 1.0 for DR with normal concentration RN and 1.5 for DR with over concentration RO. In the above formula, RN, GN, BN, RO, GO, B
Obviously, another concentration value of O can be used.

The above equation (6) is a method of obtaining by a relational expression including the image density value of one color and a preset set density value in order to increase the value of the color collection Aj from the middle density to the high density. It is not limited to the equation (6). As another method, for example, it may be based on a table value in which the value of the color collection Aj is associated with the image density value. Further, other relational expressions such as A _R = K11 (DR-DN) A _G = K12 (DG-DN) A _B = K13 (DB-DN) can also be used. By using these relational expressions, the high-density non-linear exposure area and the reciprocity law failure of the printing paper are greatly influenced, and the printing exposure conditions of the reference film type are corrected.

Further, in this embodiment, the gamma balance correction value Pj is used to set the density balance of the reference film type as a reference. As the correction value Pj, a value corresponding to the reciprocal of the γ value of the reference film type may be used, and as shown in FIG. 15, the average value of R, G, and B colors of the over density based on the normal density is used.
dWO = dWO = {(RO-RN) + (GO-GN) + (BO-BN)} / 3 ...
(7) Then Pj (P _R , P _G , P _B ) becomes Becomes As a result, the difference in the inclinations of the three colors (that is, the density balance) is corrected.

Therefore, the exposure amounts er, eg, eb are as shown in the following expression (9).

Then, the exposure control values Er, Eg, and Eb can be determined by setting parameters unique to the automatic printer, parameters of the copying material, and the like with respect to the exposure amounts er, eg, and eb in the above equation (9).

Further, by applying RU, GU, and BU to the above RO, GO, and BO, the same can be applied to the low-density portion.

When the exposure amount of the film to be printed is determined by the above equation (9), Aj has little or no effect on the reference film type, and the film to be printed depends on the difference in the density balance of the three colors from the reference film. The effect of Aj is obtained. Aj is not limited to the equation (9), and the difference or ratio of the concentration balance between the reference film type and the film to be printed may be directly taken and multiplied by Aj. Alternatively, the difference or ratio between the color balance of the reference film type and the color balance of the film to be printed is
May work. The density balance of the three colors of the reference film and the density balance of the film to be printed can be determined from the gradation of the three colors of each film.

Then, the exposure amount determining means 44 controls the printing exposure amount by controlling the motor 16 based on the exposure control values Er, Eg, Eb obtained as described above.

The present invention is not limited to this embodiment, and can be applied to various different devices and configurations. For example, the present invention can be applied to the following white color subtraction type printer, scanning type color copying apparatus, and other color image forming apparatus.

Next, a white-light reducing type automatic color photographic printing apparatus to which the present invention can be applied will be described. In addition, in FIG.
The parts corresponding to those in the figure are designated by the same reference numerals and the description thereof will be omitted. The exposure amount determining unit 50 is the same as in FIG. In this white light reduction type automatic color photoprinting device, a light control filter 60 is provided between the lamp house 10 and the mirror box 18.
And a color light regulation filter 62 are arranged. As is well known, the dimming filter 60 is composed of three filters, a Y (yellow) filter, an M (magenta) filter, and a C (cyan) filter, and is exposed by being controlled by the exposure amount determining unit 50. The amount is controlled. The color light regulation filter 62 includes a BG regulation filter a for regulating the B light long wave and the G light short wave, a GR regulation filter b for regulating the G light long wave and the R light short wave, an ultraviolet cut filter c, and an infrared cut filter d. It consists of four filters. In this color light regulation filter 62, B light is formed by the combination of the ultraviolet cut filter c and the BG regulation filter a, and G light is formed by the combination of the BG regulation filter a and the GR regulation filter b, and the infrared cut filter d is formed. R light is formed in combination with the GR regulation filter b. The transmission characteristics of the color light regulation filter 62 are as shown in FIG. 13 (3).

The following filters are attached to the two-dimensional image sensor 28. That is, a B filter having a transmittance long-wave end in the absorption band of the BG control filter a, a G filter having a transmittance short-wave end in the absorption band of the BG control filter a and a transmittance long-wave end in the absorption band of the GR control filter b. Filter,
An R filter having a transmittance short wave end in the absorption band of the GR regulation filter b is used. The transmittance characteristics of the R, G, and B filters are as shown by the solid line in FIG. 13 (2), and the transmittance distribution when combined with the color light regulation filter 62 is as shown in FIG.
It becomes as shown by the broken line in Fig. 13 (2). The R, G, and B filters are used by arranging the respective colors in a mosaic pattern such as Japanese Patent Application No. 61-22155, a stripe pattern, or a checkered pattern. Further, the spectral sensitivity of the color paper when corrected by the color light regulation filter 62 is as shown in FIG.
The spectral sensitivity (solid line) of the uncorrected color paper is indicated by a broken line, which substantially matches the spectral sensitivity distribution of the photometric system shown in FIG. 13 (2).

Then, after the spectral sensitivity distributions are matched as described above, photometry is performed using the color light regulation filter, and the printing conditions of the reference negative film type are corrected as described above, and printing is performed using the Y, M, and C filters. As a result, film types having different characteristics can be satisfactorily printed by the white light subtraction method. The present invention is naturally applicable even if the photometric system and the exposure system are separately arranged in the white light subtractive color printing method.

As described above, according to the present embodiment, printing of various films can be satisfactorily performed by correcting the printing and exposure conditions of the reference film type according to the film characteristics, and therefore various printing can be performed only by determining the printing conditions of the reference film type. It is possible to print with high quality from underexposure to overexposure of the film. Also, since various films are printed based on the printing exposure conditions of the standard film type, even if various characteristics of the negative developing machine, the negative film, the automatic color photographic printing device, etc. are changed, one print is made. Since only the condition, that is, the print condition of the reference film type needs to be managed, proper management can be easily performed. In addition, since appropriate conditions are automatically corrected for each film type, appropriate prints can be produced for various films.

The color collection Aj may be defined by a function of Dj, a table value of Aj with respect to image density, and Daj and Dbj in the determination of Aj are not limited to densities such as RO, RN, and GO, and XO, XN, XU (X = R, G, B, O is over-concentration,
N is a normal density and U is an under density) or a value obtained from a large number of image data,
It may be an appropriate constant. Also, instead of determining Aj, the value of Aj × slope control value or Aj · Pj ×
You may decide the value of a slope control value.

As the image density obtained from the photometric value, in addition to the screen average density, an average density such as a high density portion average density, a medium density portion average density, a low density portion average density of the screen may be selectively used. In the above description, the color deviation is represented by using dW, but the present invention is not limited to this, and dG or another one color may be used in place of dW, or the color ratio of each color may be used. Aj may be a matrix type by adding other correction factors. The exposure amount determination function formula is not limited to the above embodiment. The determination of Pj is not limited to the above formula, and for example, instead of dWO, GO-GN or GO, another concentration value may be used instead of GN.

Further, although an example in which the R, G, and B colors are corrected has been described above, a difference in density balance may be detected, and the correction using Aj may be performed only for a color whose difference exceeds a predetermined value.

[Brief description of drawings]

FIG. 1 is a schematic view showing a color-adding type automatic color photographic printing apparatus to which the present invention is applicable, FIG. 2 is a plan view of the rotary disk of FIG. 1, and FIG. 3 is a schematic view of the filter of FIG. Figure 4 shows R
Diagram showing the characteristics of the filter, Fig. 5 (1), (2),
(3) is a diagram showing the color paper in the additive color method, the spectral sensitivity distribution of the two-dimensional image sensor, etc., FIG. 6 is a diagram showing an example of the characteristic curve, and FIGS. 7 (1), (2), ( 3) is a diagram for explaining the film characteristics, FIG. 8 is a diagram showing a region for selecting a photometric value, FIG. 9 is a diagram of a curve for converting the photometric value, and FIG. 10 is a density for exposure control. FIG. 11 is a flow chart for obtaining a value, FIG. 11 is a diagram showing a color region, FIG. 12 is a schematic diagram showing a white light subtractive automatic color photographic printing apparatus to which the present invention can be applied, and FIGS. 13 (1), (2) ) And (3) are diagrams showing the color paper in the subtractive color method, the spectral sensitivity distribution of the two-dimensional image sensor, etc., and FIG. 14 is a diagram showing the characteristic curve of the paper in which G is biased to the high density side, FIG. FIG. 3 is a diagram for explaining a gamma balance value. 12 …… Infrared cut filter, 14 …… Rotating disk, 18…
… Mirror box, 20 …… negative film, 26 …… color paper.

Claims (6)

(57) [Claims] 1. A photometric data is obtained by dividing a whole or a part of a film image of a film to be printed into a large number and measuring the photometric data, and a photometric exposure condition of a reference film type and photometry belonging to a specific color region. In a method of determining a photographic printing exposure amount, which determines the printing exposure amount based on the image density values of the three colors obtained based on the data, 3 of the films to be printed with respect to the density balance of the three colors of the reference film type.
A method for determining a photographic printing exposure amount, which comprises correcting the printing exposure condition of the reference film type for at least one selected color based on a difference in color density balance to determine the exposure amount. 2. Printing should be performed by a functional expression including an image density value of one color out of image density values of three colors obtained from photometric data belonging to the specific color area and a preset set density value. A color correction value for correcting a difference in density balance of three colors in a high density portion or a low density portion of a film is obtained for at least one color, and an exposure amount is determined by correcting a printing exposure condition of the reference film type. 1) The method for determining the photographic printing exposure amount described in 1). 3. A method for determining a photographic printing exposure amount according to claim 2, wherein the color correction value is increased from a medium density portion to a high density portion of the film to be printed or from a medium density portion to a low density portion. 4. A method of determining a photographic printing exposure amount according to claim 2, wherein the color correction value Aj is obtained based on the following equation. Aj = k1j (Dj-Daj) / (Dbj-Daj) + k2j where j represents any one of red, green and blue,
Dj is the image density value of j obtained from the photometric data belonging to the specific color area, Daj and Dbj are preset density values of j whose magnitude relationship is Dbj> Daj, and k1j and k2j are color corrections including 0. It is a coefficient of j that determines the magnitude of the value Aj. 5. The exposure amount is determined by multiplying the image density value of the three colors or a value corresponding to the image density value by the reciprocal of the gradation of the three colors in the specific density range of the reference film type. 1) The method for determining the photographic printing exposure amount described in 1). 6. The photographic printing exposure according to claim 1, wherein the density balance of the three colors of the reference film type and the density balance of the three colors of the film to be printed are determined from the gradations of the three colors of each film. How to determine the amount.