JPS6377047A - Determining method for exposure value of photographic printing - Google Patents

Abstract

PURPOSE:To reduce the frequency of reprinting by calculating an evaluated value regarding the correction value of exposure and deciding that the exposure correction value is further corrected or that photographic printing is carried out according to the evaluated value. CONSTITUTION:The printing condition of a film is determined according to a read signal from a negative read part 7, which reads the transmission density of a negative film 2 by frames or in picture element units. The correcting value CV and estimated residual beta of some negative image are calculated from the relation of the probability of excellent printing and an estimated residual quantity DELTACV and an excellent print of the object negative can be estimated with the estimated residual and probability gamma. This evaluation function f(DELTACV) is introduced to set a permissible print level previously as the reference value of the evaluated value and when the evaluated value does not reach the reference value, no printing operation is performed or an operator is urged to judge it. Consequently, a print higher than constant quality is secured and the rate of reprinting is lowered.

Description

[Detailed description of the invention] 1. Industrial application field 1. The present invention relates to a method for determining exposure amount for photographic printing.

Background of the Invention - In general, photographed negative images are not necessarily photographed under conditions suitable for printing, and are subject to over- and underexposure1 various photography light sources, out-of-focus conditions, small & There are changes due to factors such as bulges. For this reason, in photographic printing, the exposure amount and color balance are sometimes adjusted appropriately for each frame of the negative image. Among these methods, there is a method for adjusting the exposure amount, which is determined from the average transmission density (LATD) of each frame of a negative image. This method often fails to correct negative images where the brightness structure is extremely biased compared to the normal brightness distribution.

Therefore, there is a method of measuring the transmission density of a negative image divided into multiple areas, classifying it into a representative pattern of the subject scene based on the magnitude of the density difference and the ei degree distribution, and statistically calculating the basic exposure amount according to the scene. Proposed.

Problems to be Solved by the Invention - Conventional exposure determination is determined by statistical methods, which may result in inappropriate exposure settings depending on the negative image. There was a problem that caused the rewrite to occur.

An object of the present invention is to provide an exposure amount determining method that reduces the occurrence of reprinting.

-Means for Solving the Problems- In order to achieve the above-mentioned object, the present invention calculates an evaluation value for the exposure correction amount in a method for determining the exposure amount of a photographic printer, and uses this evaluation value to determine the exposure amount. The system determines whether to further correct the amount of correction or to print the photo.

One Embodiment - FIG. 1 is an apparatus configuration diagram showing one embodiment of the present invention. The negative film unit 1 feeds the roll film containing the negative film 2 frame by frame to the optical printer 3 position, and the optical printer 3 transfers the negative image of each frame to the photographic paper 4 while the negative film 2 is being transported. Configured to bake. Photographic paper 4
is taken out as a roll paper from the vapor unwinding section 5.

The printing conditions of the optical printer 3 are given as setting values from a processing device 6 such as a computer,
The conditions for this printing are determined according to the read signal from the negative reading section 7. The negative reading section 7 is located before the negative printing station t of the optical printer 3 and reads the transmission density of the negative film 2 for each station and for each pixel.

Among the conditions for printing by the processing device 6 described above, the method of determining the exposure amount will be explained in detail below in comparison with the conventional method.

The conventional exposure amount, ie, exposure time TO, is expressed by the following general formula.

To = f (D) + f (Cv) +・−+ f (
z) - (1) In equation (1), f (D) is obtained as a function of the average transmission density, f (CV) is obtained as a function of the exposure correction amount CV by a statistical method, and these functions are In addition, the function f (
z), etc.

Here, the exposure correction amount Cv is determined by the following equation (2).

CV =, ΣCI Xt + b-...-(2)1
=0 However, XI is a representative parameter in the concentration distribution, C1 is a coefficient, and b is a constant.

In these conventional methods of determining the exposure amount, the exposure amount is determined primarily based on the transmission density detection signal of the negative image.
Depending on the photographing conditions of the negative image, an unsuitable printing condition may result, that is, an unsuitable exposure amount.

Therefore, in the method of the present invention, the evaluation values of various correction elements can be arbitrarily set, and by this setting, the number of non-conforming exposures is minimized, and as a result, the occurrence of reprinting is reduced.

For example, the predicted residual amount (ΔCV ←l 0
CV-CV l) is ACV=, Σdi Xi +e・
(3) It is determined by l=0. However, xl is a representative parameter in the concentration distribution, di is a coefficient, and e is a constant.

Here, the relationship between the probability of successful printing and the predicted remaining amount ΔCv is shown as shown in FIG. Now, assuming that a correction value Cv and a prediction residual β are calculated for a certain negative image, it can be predicted that a negative to be printed using the correction value Cv can be printed satisfactorily with a probability of γ using the prediction residual β.

An evaluation function f(Δ Cv) as a linear or quadratic equation Off (ΔCV)<1 It can be defined within the range of

By introducing the evaluation function value as described above, an allowable print level can be set in advance as a reference value for the evaluation value, and if the evaluation value is less than the reference value, printing will not be performed or the operator will be prompted to make a decision. Therefore, certain quality can be compensated in the printing process.

Furthermore, if the evaluation value does not satisfy a certain condition, it is also possible to search for a target appropriate correction amount by using another exposure control algorithm. By operating using such evaluation values, the quality of the printing process can be managed to a certain level or higher, and the incidence of reprinting can be reduced.

In the embodiment, a case is shown in which an evaluation value is introduced for one exposure correction function, but this becomes even more effective by introducing individual evaluation values for a plurality of functions.

Effects of the Invention - As is clear from the above description, the present invention introduces an evaluation value for the exposure correction amount, so that it is easier to obtain the evaluation value and Depending on the setting method, it is possible to compensate for print quality and reduce the occurrence of reprinting, and when used in combination with other algorithms, it has the effect of increasing the probability of finding the appropriate exposure amount.

[Brief explanation of the drawing]

Fig. 1 is an apparatus configuration diagram for explaining the method of the present invention;
The figure is a characteristic diagram of the prediction residual ΔCv and the probability γ of good printing in the method of the present invention. 2... Negative film, 3... Optical printer, 4... Photographic paper, 6... Processing device. 7... Negative reading section.

Claims (1)

[Claims] 1) The exposure amount determination method for a photographic printer is characterized in that an evaluation value for the exposure correction amount is calculated, and based on this evaluation value, it is determined whether to further correct the exposure correction amount or to perform photographic printing. How to determine the exposure amount for photo printing.