JPS6398648A - Determining method for photographic printing condition - Google Patents

Abstract

PURPOSE:To facilitate the setting of conditions because condition set values are very close among respective film kinds by determining the quantity of exposure according to the value calculated by using the light measured value of a film and printer control characteristics. CONSTITUTION:The density 2 of a reference negative is found from respective density steps of light measurement 1 obtained by an image sensor, a photodiode, etc., and film characteristics 3 are calculated on the basis of the reference negative density 2 and stored 10 in a memory by negative kinds. In addition, the print condition value 4 of a reference film kind is found by the method of trial and error or a determined procedure and stored 10 in the memory. A correction quantity DELTA for correcting the quantity of exposure is calculated 11 by using the film characteristics 3 stored in the memory. An exposure control quantity 23 is found after the photo-graphic printing condition is set, and printer control characteristics DELTA are read out to determine the exposure quantity, thereby performing photographic printing operation 25.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for determining photographic printing conditions such as printing exposure.

(Technical background of the invention and its problems) Conventional photo printing equipment (printer) conditions are set by setting a standard negative film (hereinafter referred to as standard negative) in the printer, performing a trial printing, and determining the total film density. This was done through trial and error to obtain the desired color and density across the area. Therefore, in order to set the printing conditions for many types of negative films, standard negatives for each type of negative film are required, and it is extremely difficult to create standard negatives for each type of negative and to set and manage the conditions using them.

Therefore, it has been strongly desired to be able to print various negative films with one set of conditions, also from the viewpoint of convenience in printer operation.

As shown by the solid line in FIG. It is well known that when exposed under conditions in which the amount of light is equal to the amount of light received by the photometer of the printer, different types of films are printed with the same color density corrected.

However, there has been no particularly effective method for correcting the non-linear portion of the film characteristic curve under the same conditions. As a conventional technique, for example, there is a technique shown in Japanese Patent Application No. 49-29641, but in this method, both the upper and lower ends of the film characteristic curve shown by the solid line in FIG. It is shown that the curved portions (underexposed areas, overexposed areas) are extended and approximated as shown by a dashed line, and the printing exposure iE is controlled based on the average density value obtained therefrom. However, a drawback of this method is that it does not take into account any changes in the density of the main part of the image (subject) (hereinafter referred to as main part density) in the curved portions of the underexposed and overexposed parts. In other words, although consideration is given to changes in the average density due to saturation of the film characteristic curve, no sufficient correction is made even though the main density is also affected at the same time. Furthermore, with the above approximation method, it is difficult to set the position at which the film characteristic curve is extended in a straight line. In particular, when the linearity of the film characteristic curve is poor, it is difficult to determine the set point, and the determined set point significantly changes the result of the exposure amount obtained.

In addition to the above-mentioned problem, there has been a desire for a method that can uniformly control photographic printing conditions and exposure correction normalization conditions (for example, Japanese Patent Application Laid-Open No. 145620/1983). Conventionally, both have been controlled independently, so management of both has been extremely important. For example, even if the print becomes reddish due to a change in exposure conditions, the exposure correction section cannot detect this change and cannot make any corrections.

(Object of the invention) This invention was made under the above circumstances,
SUMMARY OF THE INVENTION An object of the present invention is to provide a method for setting photographic printing conditions that makes it easy to set photographic printing conditions and also controls the exposure amount and corrector in a unified manner based on film characteristics.

(Summary of the Invention) The present invention relates to a method for determining photographic printing conditions, in which a printer control characteristic for correcting a non-linear part of the density characteristic of a film is stored, and a photometric value of a printing film and the printer control characteristic are stored. The exposure amount is determined based on the value calculated using . Further, in another invention, the screen average density and main part density of a normal exposure standard image are respectively DN and PN, and the screen average density of a printing film and the main part density of a standard image having the same screen average density are respectively D and PN. If P is the slope control value of the photographic printer and K is a constant, then +15E- is +a (D-f(D))f(D)(
The exposure amount is determined by Ps-11+)-(PD).

(Embodiments of the Invention) In the present invention, as shown in FIG.
nsmittance density) or an image sensor (for example, the method shown in Japanese Patent Application Laid-Open No. 154244/1983), a reference negative density 2 is obtained.

The reference negative has reference frames A to J exposed and developed at predetermined exposure intervals as shown in FIG. It is desirable to be. Furthermore, as a reference negative, areas A to J of different densities may be developed within one frame as shown in Figure 3 (A), or areas A to J with different densities may be developed within one frame as shown in Figure 3 (CB). It may be developed together with the image 3. Furthermore, areas A-E and F-J having different densities may be provided for each frame as shown in FIG. 3(C).

For such a reference negative, a reference negative density 2 is determined from each density step of photometry 1 using an image sensor, photodiode, etc., and film characteristics 3 as shown in Fig. 4 are calculated based on this reference negative density 2. Then, it is stored in memory (lO) for each negative type. Note that the film characteristic 3 is expressed as a negative density for a photographic exposure f''5H.

Apart from this, printer condition values 4 for the standard film type (for example, standard negative density, exposure correction amount for printing the standard negative to the desired density, slope control value, standard exposure time, etc., in part or in full) is determined by trial and error or by a predetermined procedure and stored in memory (lO).

The film characteristics 3 and printer condition values 4 are obtained for each of the three colors of nGB and stored in the memory (10), and the film characteristics 3 can also be used for setting the conditions for normalization 21. In addition, instead of determining the standard negative density 2 using a standard negative, normalization conditions are automatically corrected for fluctuations in negative film development, etc. using an average value obtained from the cumulative density of a large number of negative films for printing. Instead of the rate negative shown in FIG. 2 or FIG. 3 (8) to (C), a negative film in which a certain subject is photographed by changing the exposure amount may be used.

As described above, the film characteristics 3 and the printer condition values 4 for the reference negative film type are determined and stored in the memory (10) L. Exposure amount is determined using the film characteristics 3 stored in the memory. A correction amount Δ for correcting is calculated (ii). FIG. 4 shows an example of a method for calculating the correction amount Δ. The upper left diagram in Figure 4 shows film characteristics 3, and the lower part of the diagram shows the amount of photographic light 4E for each part of the film surface divided into approximately 200 parts when an average scene is exposed on the film surface. R1 (underexposure), R
2 (normal exposure) and R3 (overexposure). Using the frequency distribution R1°112.113, negative density distributions Q1 to Q3 as shown in the upper right diagram are obtained from film characteristics 3. In negative density distribution 01 to Q3,
In each case, P is the main part density and D is the screen average density. The average image is usually PAD and (p-o
) is constant, and photo printing is performed based on the average density of the screen. In addition, the frequency distribution R of the shooting light amount QE
RPI NRP3 of 1 to R3 indicates the average light amount of the main subject of the average scene. The main concentration P is R
Based on PI to RP3 and film characteristics, the screen average density can be determined from the density distribution QINQ3. The frequency distribution R2 and the main part light amount RP2 can be determined as the average value of the subject from the density distribution and main part density of a large number of standard images.

R1, R3, due to the increase or decrease of constant light from R2, RP2,
R.P.

RP, can be determined.

Due to the nonlinearity of film characteristic 3, for example, the difference between normal and underexposed sides is (PN-ON) > (P
U-DU). Therefore, when printing an underexposed printing negative by determining the printing exposure amount based on the screen average density DU, the main part density P'U will be overexposed. Conversely, an overexposed printing negative will be underexposed. For this purpose, a slope control value a has been conventionally used and is determined by trial and error for each type of film.

Here, the exposure control value for properly printing the main part density Pu of underexposure is Pu-(PN-ON), and the correction amount Δ for the screen average density Du of underexposure is Δ-(PN-DN) − (Pu-Du) ---
(1). Printing exposure ME is "y" for negative density.
+a-D to E-,,,,,,...(2
), and if Δ= f (D), then 11=5E'- +a・(D-f (D)) --
- By correcting according to (3), even overexposed or underexposed negatives for printing can be printed with the difference between the main part P and the screen average density always kept constant. Note that in the above, a is a slope control value and K is a constant. Normally, a standard negative with a pattern that has the characteristics of a standard scene is used to set the printing conditions. By using it as memory data, it is possible to deal with various negative films.

The light intensity distribution and main part density of the standard negative are shown in R1-R3 in Figure 4.
By using multiple windows such as Q1 to Q3, the correction amount from under to over is Δ= f (D)
It is possible to obtain This correction ff1f(D) is defined as a printer control characteristic.

Since printer control characteristics depend on the shape of the film characteristic curve, they must be determined for each film type. The slope control value is determined by trial and error for each type of negative so as to produce a constant printed image, but the printer control value is a correction value to keep the difference between the main part density of a standard image and the screen average density constant. , is automatically determined from statistical data on the amount of light hitting the film surface and film characteristics. That is, the printer control characteristics are a group of values for correcting nonlinearity of film characteristics by taking printer characteristics into consideration. The solid line in FIG. 5 shows the exposure characteristic expressed by the above equation (2), and the dashed line shows the corrected exposure characteristic expressed by the above equation (3). As in the above embodiment, the correction amount Δ, that is, the printer control characteristic, is determined so that the difference between the main part density P of the standard image and the screen average density is the same over the entire range from underexposure to overexposure (11). , store (10)L in memory. Printer control characteristics are stored as table values or function expression parameters.

After the photographic printing conditions as described above are set, the negative film to be actually printed is photometrically measured 211 with an image sensor or the like, and then normalized 211 according to normalization conditions. , and then image features 2 such as maximum density, minimum density, color featurer, etc.
2, and use a conventionally known exposure calculation formula (for example, JP-A-60
177337), and the exposure control amount 23 is determined based on the screen average density. Then, according to the exposure control amount, the corresponding printer control characteristic Δ stored in the memory is read out, the exposure amount is determined according to the above equation (3), and photographic printing 25 is performed.

The above example describes an example in which exposure control is performed based on the screen average density. However, instead of using the screen average density, various exposure control values can be used, such as the maximum Values including correction amounts can also be used.The method of the present invention is not limited by the above-mentioned embodiments, flowcharts, etc.

Still another method is to predetermine printer control characteristics for each film type and store them, thereby omitting the step of determining the film characteristics.

(Effects of the Invention) As described above, according to the method of the invention, by using the printer control values, the condition setting values for each film type are very similar, so one condition may be sufficient. Conditions can be easily set for each. Furthermore, the printer control values can be used automatically or fixedly, and there is no operational complexity. Additionally, since exposure control and normalization for exposure compensation amounts are determined based on common film characteristic data, management and
It is excellent in terms of accuracy, and can automatically detect changes in film characteristics due to changes in negative development, etc., and has the advantage of being able to automatically correct printing conditions.

[Brief explanation of the drawing]

Figure 1 is a flow diagram showing an example of the method of this invention, Figure 2 is a diagram showing an example of a reference negative used in this invention, and Figures 3 (8) to (C) each show other examples of the reference negative. Figure, 4th
5 and 6 are diagrams for explaining the method of this invention, and FIG.
The figure is a diagram for explaining the setting of conventional photo printing conditions. 1.20...Photometry, 21...Normalization, 3...Reference negative density, 3...Film characteristics, 4...Printer condition value, 23...Exposure control amount, 25... Burning. Applicant's agent Yuzo Yasugata (C) Ditch 3 Figure $6 Figure $4 Figure Negative Density Figure 5 Procedural Amendment December 3, 1985 Commissioner of the Japan Patent Office Black 1) Meiji A. 1, Indication of the case 1985 Patent Application No. 244974 2 Name of the invention Method for determining photo printing conditions 3.7 Sanno wo Yasha 5, “Claims” and “Detailed description of the invention” of the specification to be amended
column. 6. Contents of amendment (1) The scope of the claims of the present application is corrected as follows. ``Claims (1) In a photographic printing apparatus, printer control characteristics for correcting the non-linear portion of density characteristics of the film are stored and calculated using the photometric values of the printing film and the printer control characteristics. (2) A method for determining photographic printing conditions, characterized in that the exposure amount is determined based on the value of the normal exposure standard image. Let the main part densities of the standard image having the average density and the same screen average density be D and P, respectively, and the anal density DN and PN
, D, P is the printer control value obtained from f (D
), and the slope control value of the photoprinter is a,
A method for determining photographic printing conditions, characterized in that when K is a constant, the exposure amount is determined by B = 5E - +a (D - f (D)). (2) In the specification, page 6, line 4, insert ``D and P, and after J, ``The printer control value obtained from the densities DH, PN, D, and P is f (D).'' do. (3) Same, page 6, line 7 r f (D)・(PN-
DN) -(PD) Delete J. (4) Delete "usually P>D" on page 9, line 13. (5) Same, page 10, line 5, r after “for example”
If p>o, insert ". (6) Delete 'DuJ' on page 10, line 18. (7) Delete "Slope control value . . . to be determined, but" in the 7th to 9th lines of page 12.

Claims (2)

[Claims] (1) The printer control characteristics for correcting the nonlinear part of the density characteristics of the film are stored in the photographic printing device, and the exposure amount is calculated using the photometric value of the printing film and the printer control characteristics. A method for determining photo printing conditions, characterized in that: (2) The screen average density and main part density of the normal exposure standard image are respectively D_N and P_N, the screen average density of the printing film and the main part density of the standard image having the same screen average density are respectively D and P, and the photograph When the slope control value of the printing device is a and K is a constant, the exposure amount is determined by logE=K+a{D-f(D)} f(D)=(P_N-D_N)-(P-D). A method for determining photo printing conditions, characterized in that: