JPS5929848B2 - Photographic printing exposure control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention solves density defects (
This relates to a photographic printing exposure control method for obtaining photographic prints printed with appropriate printing density even from negative film images containing (subjective, density, area), especially negative films whose main parts are not located in the center of the screen. This invention relates to a method for obtaining appropriate photographic prints from images.

Conventionally, as this type of photographic printing exposure control method, a method disclosed in Japanese Unexamined Patent Publication Nos. 51-1128 by the present applicant has been proposed. This method involves measuring the transmission density of a negative film screen to generate a photographic printing exposure control signal, which includes detecting multiple densities of main parts of a negative film image by a photoelectric detection means, and using a photoelectric detection means. Discriminating the maximum value and minimum value of the output, determining the difference between the maximum value and the minimum value, nonlinearly converting the output of this difference, and converting the output of the converting means and the output of the minimum value discriminating means. This is a photographic printing exposure control method that includes addition, and controls the printing exposure by the output of the adding means. According to this method, printing exposure is controlled only by the previous average transmission density. Various types of negative film images for which it was not possible to obtain satisfactory photographic prints with other methods, such as negative film images with density defects, color negative film images with color defects, extremely high tone differences or extremely low tone differences, Satisfactory prints can also be obtained from negative film images, etc. However, this method has the following drawbacks: In this method, the object for density detection is the screen of the negative film. Since the image is limited to the main part centered on the center of the image, for example, if the main subject is far off the center and outside the area targeted for density detection, it may not be possible to obtain satisfactory results. This is because (1) the main subject is often placed almost in the center of the negative film screen; (2) in reality,
A method of controlling the photographic printing exposure amount based on density information obtained from the main area centered on the center of the screen of negative film produces more satisfactory photographic prints than a method based on density information obtained from the entire screen of negative 7 film. The root cause of this is that it is based on two empirical facts: the probability of obtaining . The present invention eliminates the drawbacks of the conventional methods mentioned above,
It is an object of the present invention to provide a novel photographic printing exposure amount control method that allows suitable photographic prints to be obtained even from negative film images whose main parts are not located in the center of the screen. The present invention has been made to achieve the above object, and includes a method for controlling the photographic printing exposure amount by measuring the density of a plurality of parts of a negative film screen using a photoelectric detection means. The basic method is to find the difference in the output value of the part where the output value is, compare this difference value with a preset value, and selectively adopt the density signal of the part where the output exceeds the set value. The photographic printing exposure method is characterized in that the exposure amount is determined based on the density of the main part of the negative film image by weighting the adopted density signal and determining the characteristic value for controlling the printing exposure amount. The other method is to use the adopted density signal and the number of density signals to obtain the characteristic value f1 for controlling the printing exposure amount, and also to use the density signal from the entire negative film screen and the number of density signals. The characteristic value F2 for controlling the printing exposure amount is determined by the same characteristic value calculating means used to determine the characteristic value f1, the characteristics of the negative image are classified according to the characteristic values f1 and F2, and the characteristics of the negative image are classified according to the characteristics of the classified negative image. This exposure amount control method with photographic lines is characterized in that the exposure amount is determined based on the density of the main part of the negative film image using different calculation means.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram illustrating an embodiment of the invention.

In the figure, X is a photoelectric conversion means for detecting the density of the negative film screen, Y is a means for determining the difference between the outputs of the conversion means in adjacent parts, T is a constant generator, Z is a comparator, and A is a characteristic. It is a value (for example, average transmitted density) calculation means. FIG. 2 is an explanatory diagram of the case where density detection of multiple parts of a negative film screen is carried out by a scanning means.
, j indicates the scanning direction. In this embodiment, by scanning the negative film screen, the photoelectric conversion means X generates density signals Di-1, J from a plurality of parts.
．． Di. j. Di+1, j -...1... is detected, the difference is calculated by the means Y for calculating the difference between these outputs, and this value is combined with a preset value sent from the constant generator T. , and when δ is a preset value, ΔDi. When jl〉δ・・・・・・
...Di-1. j, Di. Adopt j.

△Dij (when ≦δ...Di-, .
JlDi. The density signal is selectively employed, such as not employing j.

Next, the density signal Di-1. j,. Di. j・・−
. . . are weighted and defined as, for example.

By using the density signal D''I. At the same time, the adopted density signals are counted to find the total number, and (total number of adopted density signals)/(number of adopted density signals) is calculated. The printing exposure amount is controlled. FIG. 3 is a block diagram showing another embodiment of the present invention.

In the figure, X, Y, T, Z, and A indicate the same means used in Fig. 1, A'' is the same characteristic value calculation means as A, and B is a means for calculating the difference between the outputs of A and A''. . The operation of this embodiment is based on the output of the characteristic value calculating means A described in the previous embodiment, that is, the characteristic value based on the density signal from the remaining part after removing the low contrast part of the negative film image (for example, in the case of average density) is the sum of the number of employed density signals/the number of employed density signals) and the output of the characteristic value calculating means A'', that is, the characteristic value based on the density signal obtained from the entire negative film image (without removing low contrast areas). For example, in the case of density average, the difference between the sum of density signals of all screens/the number of density signals of all screens is obtained by means B to obtain a photographic printing exposure amount correction signal. This figure shows that the present invention can be used additionally in a photographic printing apparatus that uses a conventional photographic printing exposure control method using only characteristic value calculating means A (for example, average transmission density detecting means). It is a block diagram showing still another embodiment of.

In the figure, X, Y, T, Z, A, N and B indicate the same means as used in FIG.
, A5, and C is a means for selecting one of the outputs of Al and A2 based on the output of B. In this embodiment, in order to solve the asymmetry between the positive side and the negative side of the printing exposure amount correction based only on a single characteristic value, the method of the photographic printing exposure amount correction is based on the outputs of the calculation means A and A'. It is characterized by being changed depending on the difference. That is, a means A1 for calculating a characteristic value having a large effect on the positive side of the correction and a means A2 for calculating a characteristic value having a large effect on the negative side of the correction are selected in advance, and the calculating means A, A'f ) Depending on the difference in output, one of the calculation means is selected and used as a photographic printing exposure correction signal, and the calculation means A, A
The major feature of this system is that it is possible to change the method of correcting the photographic printing exposure amount based on the difference in the output of ``. The method of employing the concentration signal will be explained in some detail.

Density signal Di-1. obtained by scanning the negative film screen shown in FIG. j, Di. j. Di+1. j...
It is conceivable to assign various weights to . (1) In the case of weighting two adjacent parts.

The density difference △Di. By determining the boundary value δ for j, ΔDi. j as shown in the diagram above, I, ■+, ■
- divided into three bands.

Here, the band of I, that is, 1ΔDi. When jl≦δ, Di
l. j. Di. j is not adopted ■+, ■- band! △Di. When jl>δ, Di-1
．． j,. Di. j is adopted as the density value D″I.j defined by the following equation.

Here, (α1, α2) is, for example, (0, 1) or (1
/2, 1/2), etc.

(2) In the case of weighting for three adjacent parts, this corresponds to second-order differentiation, and by the above method, V2Di. By quantizing j, △Di. Decide whether to accept or reject the application based on j.

Here, it is assumed that (α1, α2, α3) is, for example, (0, 1, 0).

By removing the low-contrast portions of the negative film image using the method described above, the weight of information held by the main subject is increased.

Examples of photographic printing according to the present invention will be described below. Example 1 In the embodiment shown in FIG. 3, photographic printing was performed with each component set as follows, and compared with the conventional technique.

(1) Photoelectric conversion means X size 2TtmΦ
(2) Characteristic value calculation means A, A゛average transmission density calculation means (3) Output of constant generator T δ-0.05 (
4) 120 frames containing target negative film density defects.In addition, as a conventional technique, the method shown in the above-mentioned Japanese Patent Application Laid-open No. 511128 is as follows: [minimum density + 1/2 (maximum density - minimum density)] A method of determining standards is used.

The results are shown in the table on the next page, and the excellent effects of the present invention can be clearly understood.

Example 2 In the embodiment shown in FIG. 4, each component was photographically printed in the following manner.

(1) Photoelectric conversion means X Size 1X2m7!
L (2) Characteristic value calculation means A, A' Density average calculation means (3) Characteristic value calculation means A1 Intermediate density Average transmission density (4) Characteristic value calculation means A2 Density based on the remaining part after removing the low contrast part Average concentration obtained from the entire screen (5) Output of constant generator T δ-0.05 (
6) The target negative film contains density defects: 120 frames.The result is the number of satisfactory prints, 101 frames, and the same ratio is 84.
．． 2%, and the excellent effect of the present invention can be understood.

As described above, the present invention uses the characteristic values obtained from the remaining portion of the negative film image after removing the low contrast portions to control the exposure amount in photographic printing, and has many advantages regarding photographic printing as follows. It is something.

(1) As the weight of information on the main subject of a negative film image increases, the precision of photographic printing exposure control increases.
Improves the quality of photo prints.

(2) Satisfactory photographic prints can be obtained even from negative film images with density defects. (3) Since the correction method for photographic printing exposure can be changed between positive and negative sides, the accuracy of correction is improved and the quality of photographic prints is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a photographic printing exposure control method showing an embodiment of the present invention, FIG. FIG. 4 is a block diagram of a photographic printing exposure amount control method showing another embodiment of the present invention shown in FIGS. 3 and 4. FIG. X...Photoelectric changing means, Y...Means for determining a difference, T...Constant generator, Z...Comparator, A......・Characteristic value calculation means.

Claims (1)

[Scope of Claims] 1. In a method of controlling the photographic printing exposure amount by measuring the density of a plurality of parts of a negative film screen using a photoelectric detection means, the difference between the output values of adjacent parts obtained from the photoelectric detection means is The value of this difference is compared with a preset value, the density signal of the part where an output exceeding the set value is obtained is selectively adopted, and the adopted density signal is weighted to determine the printing exposure amount. 1. A photographic printing exposure amount control method, characterized in that the exposure amount is determined based on the density of the main part of a negative film image by determining a control characteristic value. 2. In a method of controlling the photographic printing exposure by measuring the density of multiple parts of a negative film screen using a photoelectric detection means, the difference between the output values of adjacent parts obtained from the photoelectric detection means is determined, and the value of this difference is determined. is compared with a preset value, and selectively employs a density signal in a portion where an output exceeding the set value is obtained, and uses this adopted density signal and the number of density signals to determine a characteristic value f_1 for controlling the printing exposure amount. At the same time, the characteristic value f_2 for controlling the printing exposure amount is determined using the same characteristic value calculation means that used the characteristic value f_1 to determine the characteristic value f_1 using the density signal from the entire negative film screen and the number of density signals.
1 and f_2, and the exposure amount is determined based on the density of the main part of the negative film image using different calculation means according to the classified characteristics of the negative image. Volume control method.