JPH0450570B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photographic printing exposure control device for controlling the exposure amount so that photographic prints with appropriate printing density can be obtained in photographic printing, and more specifically, the present invention relates to a photographic printing exposure control device that measures light by dividing the screen of a negative film into a plurality of parts. The present invention relates to a control device that determines a photographic printing exposure amount based on an output calculated by combining characteristic values from the photometric values. A method of dividing the screen of a negative film into a plurality of parts, measuring the light, and determining the photographic printing exposure amount based on the output of calculating characteristic values from the measured values is disclosed in Japanese Patent Laid-Open No. 51-1128 and Japanese Patent Laid-Open No. There is a method disclosed in Japanese Patent Publication No. 48-34535, which attempts to determine the exposure amount of all negative films using one calculation formula. On the other hand, the methods disclosed in JP-A-47-471, JP-A-52-23936, and JP-A-54-28131 classify the subject of negative film into several types of patterns. The coefficients of the calculation formula are selected depending on which predetermined pattern the photometered negative film corresponds to, and this calculation formula is used to determine the corresponding calculation formula. The purpose is to determine the exposure amount of negative film. The arithmetic expressions used in these methods are determined empirically or statistically from a large number of negative films, and are therefore greatly influenced by the type of subject of the negative film used and its frequency. For this reason, the average quality of finished prints throughout the year will be the best if the calculation formula is determined using the data of the huge amount of negative film that comes to the photo lab throughout the year. However, since the type of subject and its frequency vary greatly depending on the season, such as snow in winter or the beach in summer, the above-mentioned method does not necessarily fully satisfy the print quality for each season. Even with the conventional method of classifying patterns and using different coefficients in the calculation formula as described above, if the number of classifications is extremely large, it may be possible to come up with a method of determining exposure that eliminates the influence of the type of subject and its frequency. However, there is a limit to the number of classifications, and the number of classifications possible with the conventionally disclosed methods is 10 or less at most. Moreover, these pattern classification methods are very simple and do not eliminate the influence of the type and distribution of objects. For example, if (average density in the upper half of the screen) - (average density in the lower half of the screen) > 0, many backlit scenes are included, but in backlit scenes in summer and backlit scenes in winter, there is a difference between the main subject and the background. Since the contrast of the two images is different, the exposure amount must naturally be different. Unless the main subject is accurately determined, this difference in contrast is not taken into account and the exposure amount is determined using the same calculation formula, making it impossible to obtain sufficiently satisfactory print quality. As another example, in the case of a low-contrast scene, in the method of selecting a calculation formula based on contrast, a winter snowy scene, a summer seascape scene, an autumn landscape scene with colored leaves, a spring scene, etc. The number of scenes that are included differs depending on the season, and it is not possible to obtain an exposure amount that provides a sufficiently satisfactory print quality using the same calculation formula. Even though these scenes have the same low contrast, the snowy scene needs to reproduce the white of the snow with the appropriate gradation.
The main subject of each scene is different, just as it is necessary to reproduce the red of autumn leaves in an appropriate tone. One method for solving the above-mentioned drawbacks is to change the coefficients of the arithmetic expression by trial and error in accordance with changes in the type of subject and its frequency depending on the season. However, with this method, while it is difficult to select the optimal coefficients, it is even more difficult to change several coefficients at the same time. Therefore, depending on the time and circumstances, it may happen that bad conditions that are significantly different from the optimal conditions are mistaken as the optimal conditions and used as they are in determining the exposure amount. The purpose of the invention is to overcome the above-mentioned drawbacks:
It is an object of the present invention to provide a photographic printing exposure amount control device that can always determine the exposure amount using an optimal calculation formula. The present invention is aimed at achieving the above object, and measures each point on the screen recorded on a negative film, and calculates the obtained characteristic value using the following formula: X=K ₁ +K ₂・D _nax +K ₃・D _nio +K ₄・LATD+K ₅・CF +K ₆・UL+K ₇・DB+K ₈・IR (W) Here, X is the printing exposure amount, K ₁ to _{K 8} are coefficients,
Each characteristic value is as follows: D _nax : Maximum density D _nio : Lowest density LATD: Large area average density CF: Difference between the average density at the center of the screen and the average density at the periphery of the screen CF: Average density at the bottom of the screen and the difference between the average density at the top of the screen DB: Average value of the absolute value of the difference between two adjacent measurement points calculated for the entire screen IR (W): Printing exposure amount by substituting it for the number of measurement points that will be white In a photographic printing exposure control device that calculates the printing exposure amount The apparatus is provided with means for storing predetermined coefficients _K1 to _K8 , and means for determining coefficients K1 to K8 based on the photometric value of the screen or selecting the coefficients _K1 to _K8 from a designated season. The arithmetic method in the present invention is a general concept of an arithmetic expression, and may include, in addition to the arithmetic expression, selection of a correction amount, extraction of a specific point, pattern classification, nonlinear processing of characteristic values, and the like. Also, calculation formulas with specific coefficients, combinations of multiple calculation formulas, or
Various coefficients may be changed for different arithmetic expressions depending on the pattern. That is, one arithmetic method consists of a plurality of arithmetic expressions based on a plurality of pattern classifications, or one arithmetic expression when no pattern classification is performed. Changes in the types of subjects and their frequency occur mainly due to changes in the seasons, and this is due to changes in meteorological phenomena including sunlight sources, changes in the natural environment, and accompanying changes in people's behavior. Changes in weather phenomena include the intensity of sunlight, color temperature, and position of the sun; changes in the natural environment include changes in the greenness of trees, autumn leaves, and snowy scenery; changes in people's behavior from indoors to outdoors; annual events and rituals; It appears in clothing. Furthermore, due to differences in latitude and differences in the natural climate and customs of each region of the world, changes similar to changes in the four seasons can be seen in the types of subjects and their frequency. This is an empirical rule that states that in the natural world, certain causes lead to certain results, and therefore these phenomena can be repeated with a certain degree of certainty. Therefore, by preparing calculation methods that are optimal for each season and selecting and using them according to the season, it is possible to avoid deterioration in the finish quality of photographic prints due to changes in the type of subject and its frequency. can be prevented. Furthermore, in regions with high latitudes, a calculation method that emphasizes objects including snow may be prepared for winter, and this method may be selected and used during winter. For regions with low latitudes, calculation methods that place emphasis on each characteristic subject can be prepared based on the same concept. First, a calculation method that can be used in the present invention will be explained. The exposure calculation method disclosed in Japanese Unexamined Patent Publication No. 54-28131 will be described as an example. From the negative film screen, photometric values from each of the photometric points of many minute parts of the entire screen are detected by photoelectric detection means, and the maximum density, minimum density, and average density of the entire screen are detected by the photoelectric detection means. The average densities D _u , D _L , D _C , D _F of each part obtained by dividing a specific position of the negative film screen into multiple parts as shown in FIGS. is extracted as a characteristic value. The calculation formula is shown in the following formula (1). X=K ₁ +K ₂ D _nax +K ₃ D _nio +K ₄ LATD+ K ₅ CF+K ₆ UL+K ₇ DB+K ₈ IR(W)...(1) Here, the symbols are used for the following meanings. X: Printing exposure amount, D _nax : Maximum density, D _nio : Minimum density, LATD: Large area average density of neutral color 1/3 [LATD (R) + LATD (G) + LATD (B)], CF = DC −DF, UL=DL−DU, 2DB= _o Σ ⁱ⁼¹ D _i+1 −D _i /n (This is the average value of the absolute values of adjacent measurement points.) IR (W): Number of white pieces For example, The coefficient of equation (1) for subjects with contrast greater than 1.2 is the value obtained from summer subjects.
The values obtained from (A) and the winter subject (B) are different as shown in the following table.

【table】

[Table] Coefficients with large differences are related to D _nio , CF, DB, and IR (W). Since the sun's altitude is low in winter subjects, there are many shadows even outdoors. If there are many shadow areas, it is necessary to make corrections that lengthen the printing time, so D _nio , CF,
The value of the DB coefficient is increasing. Furthermore, since correction to shorten the printing time is required in the case of backlighting from snow or cloudy skies, the coefficient value of IR (W) has a larger negative value for winter subjects. If you use the calculation method that gives the coefficients for summer (A) to the calculation formula and the calculation method that gives the coefficients for winter (B) to the calculation formula, you can use the calculation method that gives the coefficients determined from subject data throughout the year to the calculation formula. The finished quality of photo prints is better depending on the season than the method. Similarly, the coefficients of the calculation formulas for other classifications, such as low contrast scenes, are determined for each season, and a calculation method for summer and a calculation method for winter are prepared. Since it is impossible to change the coefficients of such an arithmetic expression by trial and error, the optimal coefficients of the arithmetic expression for each pattern classification are determined in advance, and selected from among them are used. In addition, as another method, the pattern classification for exposure control disclosed in JP-A No. 54-28131 is as follows: (1) Low contrast (2) Under exposure (3) Over exposure (4) High contrast ( 5) Other five types of examples are shown, and calculation formulas with different coefficients are given for each. However, in northern regions where there is a lot of snow, it is better to further (6) separate the snow scene as one pattern from other subject groups and give one calculation formula. The way to classify snow scenes is as follows: IR(W)>α and (α: constant) DR(W)>β (DR(W) is the average density of IR(W), β: constant) It can be done with Figure 3 shows an example of the method described above in the form of a flowchart. Two calculation methods are prepared, one for winter (B) and one for non-winter (A), and these are selected and used. This is an example of a case. Winter pattern classification B and winter pattern are determined from characteristic values such as the maximum density, minimum density, and average density of the screen obtained from the photometric values of each of the photometric points of a large number of minute parts obtained by finely dividing the entire screen of the negative film used for printing. The photographic printing exposure amount is controlled by the output calculated by the calculation method according to the season, which is calculated using the calculation formula for each pattern. If winter pattern classification B is used in seasons other than winter, the way to distinguish the snow scene classification corresponds to the way to distinguish patterns such as backlighting,
It is no longer possible to appropriately determine the exposure amount for a backlit scene using an equation for a snowy scene. Therefore, it is effective to prepare calculation methods for winter and non-winter and select them according to the season. Calculation methods do not necessarily have to be prepared for spring, summer, autumn, and winter; for example, as in the above example, two types of calculation methods may be used, one for winter and one for all year round. There may be more than four species for the season. These calculation methods may be modified by changing only some of the calculation formulas that are significantly affected by seasons, etc., without changing all the calculation formulas of the plurality of calculation methods. When selecting a calculation method, instead of selecting a calculation method consisting of multiple calculation formulas, it is possible to select different calculation formulas depending on the type of subject group and its frequency. You may select it as a method. The plurality of calculation methods may be stored in advance in the photometry means/calculation means, or the selected calculation methods may be inputted from a floppy disk, ROM, or the like. In selecting the optimum calculation method from among the calculation methods prepared in advance, the selection can be made not only by changing it depending on the season but also by the characteristic value obtained from the photometric value of the negative film. When the type of subject and its frequency change depending on the season, region, etc., the characteristic values determined from the density of the photometered minute part also show statistical changes. Therefore, it is only necessary to examine changes in these characteristic values for a certain number of negative films and manually or automatically select the optimum calculation method. The advantage of this method of selection based on characteristic values is that it does not lose the timing of selection, and it also allows for seasonal differences depending on the region, for example, from December to February in the southern part of the country.
It is possible to accurately determine the difference in the winter of the month, which corresponds to the period from November to March in the northern countries. It is better to obtain the characteristic values used in the judgment for selecting the optimum calculation method from a larger number of negative films, and from experience it is better to obtain them from data of at least 2,000 frames, preferably 10,000 frames or more. Next, we will discuss an example in which changes in the type of subject and its frequency in multiple frames of negative film are determined by changes in the distribution of characteristic values obtained from photometric values. Figure 4~
FIG. 8 is a graph showing the difference in the distribution of characteristic values in August and January in the Tokyo suburbs, where the solid line shows the distribution in August and the broken line shows the distribution in January. (1) Figure 4 shows the distribution rate of the lowest concentration (D _nio ),
For example, when D _nio of 0.04 or less reaches 25% of the total, it can be determined that it is winter. (2) Figure 5 shows the distribution ratio of large area average concentration (LATD). For example, LATD of 0.3 or less is 20% of the total
%, it can be determined that it is winter. (3) Figure 6 shows the difference between the highest density (D _nax ) and the lowest density (D _nio ), that is, the contrast (D _nax
−D _nio ), and for example, when the contrast of 1.4 or higher reaches 10% of the total, it can be determined that it is winter. (4) Figure 7 shows the distribution rate of the number of minute parts whose density is neutral. For example, if the ratio of the number of neutral colors is (number of N ₂ or less) / (number of N ₂ or more) 0.3, It is determined that it is winter. (5) Figure 8 shows the distribution ratio of (D _nio + D _nax )/ ₂ − LATD, for example, (D _nio + D _nax )/ ₂ of 0.25 or more.
- Winter is determined when LATD reaches 15% of the total. In addition to these characteristic values, LATD(R),
Characteristic values such as the chromaticity of LATD (G) and LATD (B), the number of minute portions whose density shows a green color, UL, and CF can be used. For example, the average LATD chromaticity of many frames is plotted on the horizontal axis as LATD(R) - LATD.
When (G) is plotted on the vertical axis as LATD (G) - LATD (B), it changes depending on the season as shown in the coordinates in Figure 9, so it is not possible to judge the season based on this chromaticity. can. Furthermore, the number of microscopic areas exhibiting a green density is large in early summer, and extremely small in winter, so the season can also be determined based on this. The accuracy of the determination can be improved by using two or more characteristic values that characteristically represent seasonal changes as described above, or by using a linear formula that expands the characteristics by multiplying these characteristic values by a coefficient. Yet another way is to calculate these characteristic values using formula (1)
The season can be determined by using the correction amount obtained by inputting the information into, etc. For example, in summer, the number of negative films that require the exposure amount to be reduced by correction is greater than the exposure amount determined by LATD, and conversely, in the winter, the number of negative films that require the exposure amount to be increased by correction is greater than the exposure amount determined by LATD. many. The season can be determined by examining the distribution of the correction amount for the exposure amount by LATD. Figure 10 is a graph showing the distribution ratio of the correction amount with respect to the exposure amount by LATD. For example, (number of correction amounts) / total number, or (number of 20% correction amounts) / (number of 20% correction amounts), etc. Summer and winter can be determined by the difference in the values of . Further, the determination can be made similarly using the color correction amount. The results of determining changes in the distribution of these characteristic values or changes in the type of subject and its frequency based on the characteristic values are
It may be displayed on a CRT, an LED or the like, or it may be printed out.
Then, based on the change in this distribution, it is possible to change and select another optimal calculation method. Furthermore, the operation of the device can be programmed to automatically switch the calculation method when this distribution exceeds a certain value. In order to automatically switch the calculation method, it is possible to store the judgment results of the type of subject and its frequency changes in a medium such as a floppy disk or ROM, and to use the output signal from this medium. can. FIG. 11 is a block diagram showing the main parts of an example of an exposure determining apparatus for implementing the photographic printing exposure amount control method of the present invention. A screen of a color photographic film is scanned by a scanner 1, and the transmitted light transmitted through the color photographic film is separated into three color lights of blue, green, and red by a color separation optical element. This three-color light enters a light receiving element for blue, green, and red, for example, Photomar 2, and is measured respectively. The measurement signal of this photomultiplier 2 is
After being amplified for each color, it is sampled and held in a sample and hold circuit 4. This sample and hold circuit 4 performs sample and hold using a sampling pulse from the scanner control circuit 5. Further, since the scanner control circuit 5 controls the scanning section of the scanner 1, sample and hold is performed in synchronization with the scanner 1. As a result, a large number of measuring points regularly arranged on the screen of the color photographic film can be obtained. For example, if a color photographic film is 35 mm in size, a 22 x 34 mm area excluding the outer periphery is scanned using actual points with a diameter of 1 mm (approximately 3 mm on a color print) at 1 mm intervals. Therefore, the screen is measured at 22×34=748 measurement positions. The blue, green, and red measurement signals of each measurement point sampled by the sample-and-hold circuit 4 are sent to the logarithmic conversion circuit 6. The measurement signal is logarithmically converted by this logarithmic conversion circuit 6, and blue density B, green density G, and red density R are calculated. Specifically, when transmittance is T, log1/T is calculated. The blue density B, green density G, and red density R are
The signal is sent to the standardization circuit 7, and subjected to γ correction and sensitivity correction according to the photosensitive material. That is, the γ value and the sensitivity value, which indicate the relationship between the exposure amount and the density, differ depending on the film manufacturer and the type of film. Therefore, even if the same subject is photographed under the same conditions, the densities will be different. Therefore, we set up a key for each type of film.
By manipulating this, the concentration signal is corrected by adding a constant constant in an adder, and then the gain of the amplifier is adjusted and multiplied by a coefficient to perform γ correction. As a result, the same density is converted for the same subject. Then, the blue density B, green density G, and red density R at the measurement point are sent to the interface 8 and stored in the memory 9 whose address is specified by the measurement position signal from the scanner control circuit 5. Measured concentrations B, G, stored in memory 9
R is sent to the CPU (Central Processing Unit) 10, and the maximum density D _nax , the minimum density D _nio , and the contrast (D _nax
−D _nio ) etc. are calculated. Changes in the distribution of characteristic values are displayed on the CRT or other display means 11, while the arithmetic method selection means 1
2, that is, a plurality of calculation methods, e.g.
Select the optimal calculation method from 9C and use CPU1
0, and the exposure amount for printing on photographic paper is determined. FIG. 12 is a perspective view showing the main parts of a scanner for measuring the transmission density of a negative film in an embodiment of the exposure determining apparatus. The illumination light emitted from the light source 15 passes through an elongated slit 16, and the illumination width is regulated. The illumination light passing through this slit 16 is transmitted through a lens 17 and enters a reflecting mirror 18. The illumination light bent downward by the reflecting mirror 18 passes through the lens 19 and is directed to the color photographic film 2.
0 screen 21, and illuminates the width direction of the screen in a band shape with a width of about 1 mm. The band-shaped light transmitted through the color photographic film 20 is reflected by a scanner mirror 22 disposed below, passes through a lens 23, and reaches a slit 24.
As the scanner mirror 22, a mirror attached to a galvanometer is used,
Oscillation is performed by a sawtooth mirror control signal sent from the scanner control circuit 5 shown in FIG. An image 26 of an illuminated band-shaped portion of the screen 21 of the color photographic film 20 is formed on the slit 24 at right angles thereto. When the scanner mirror 22 is oscillated at a constant speed by a mirror control signal, the image 26 moves in a direction perpendicular to the slit 24. Therefore, a portion of the image 26 passes through the slit 24 and moves from one end to the other. The light transmitted through the slit 24 passes through the lens 27 and is separated into three colors, red light, blue light, and green light, by dichroic mirrors 28 and 29, and enters each of the photoprints 2a, 2b, and 2c. The amount of light is measured. The screen 21 is scanned in the Y direction by a scanner mirror 22, and the screen 21 is scanned by a fixed pitch in the X direction. That is, when the scanner mirror 22 completes scanning and returns to the original position, a pulse motor control signal is output from the scanner control circuit 5, and the pulse motor 30 is rotated by a certain angle. Since a film feed roller 31 is connected to the pulse motor 30, the color photographic film 20 is held between the film feed roller 31 and the roller 32 and is fed a certain distance. In this way, the density information of each part of the screen 21 of the color photographic film 20 is measured. As described above with reference to the embodiment implemented in an exposure determination device for controlling the exposure amount of a photographic printing device, the present invention is applicable to changes in the type of subject and the frequency of exposure of a large number of frames of negative film used for printing. Since the most suitable calculation method is selected from among several different calculation methods and applied, it is possible to control the photoprinting equipment to provide the optimum exposure amount according to seasonal changes, and to apply the optimal calculation method depending on the season. It is possible to improve the quality of printed photos (which clearly show seasonal characteristics).

[Brief explanation of drawings]

Figures 1 and 2 are examples of screen divisions, respectively.
Figure 3 is a flowchart, Figures 4 to 8 are graphs showing the distribution of characteristic values depending on the season, and Figure 9 is a flowchart.
The figure shows the coordinates showing changes in chromaticity depending on the season, Figure 10 is a graph showing the distribution of correction amount depending on the season, and Figure 11
The figure is a block diagram of the main parts of the exposure determining apparatus, and FIG. 12 is a perspective view showing the main parts of the scanner of the same apparatus. 1...Scanner, 2...Fotomal, 4...
Sample hold circuit, 5... Scanner control circuit, 6... Logarithmic conversion circuit, 7... Standardization circuit, 9
...Memory, 9A to 9C...Arithmetic method memory, 10...CPU, 12...Arithmetic method selection means.

Claims (1)

[Claims] 1. Measure each point on the screen recorded on the negative film to determine each characteristic value, and calculate the following formula: X=K ₁ +K ₂・D _nax +K ₃・D _nio +K ₄・LATD+K ₅・CF +K ₆・UL+K ₇・DB+K ₈・IR (W) Here, X is the printing exposure amount, K ₁ to _{K 8} are coefficients, and each characteristic value is _{as follows} . Lowest density LATD: Large area average density CF: Difference between the average density at the center of the screen and the average density at the periphery of the screen CF: Difference between the average density at the bottom of the screen and the average density at the top of the screen DB: The difference between the average density at the bottom of the screen and the average density at the top of the screen The average value of the absolute value of the difference obtained for the entire screen IR (W): Calculate the printing exposure amount X by substituting it for the number of measurement points that become white, and use this printing exposure amount X to print the screen on photographic paper. In a photographic printing exposure control device that prints photographs in winter, if the ratio of the number of frames whose minimum density is below a predetermined value to the total number of frames exceeds the standard value, these frames are considered to have been taken in winter. determining means for determining that the frames were taken in summer when the value is less than a reference value; and means for storing coefficients K ₁ to K ₈ predetermined for each of the at least two seasons; Factors K ₁ to _{K 8} depending on the season
1. A photographic printing exposure amount control device, comprising means for selecting. 2 At least the coefficients K ₃ , K ₅ , K ₇ , and K ₈ differ depending on the season, and the coefficients K ₃ , K ₅ , and K ₇ have larger values in winter, and the coefficient K ₈ has larger values in winter. 2. The photographic printing exposure amount control device according to claim 1, wherein: is a large negative value.