JPH07104568B2 - Image exposure method capable of obtaining proper exposure amount - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image exposure method, for example, two-dimensionally dividing image information of an original image such as a negative film into a plurality of pixels for detection and calculation. The present invention relates to an image exposure method in which an exposure amount and / or an exposure correction complementary amount for automatically exposing an original image is determined using a means or the like.

[Background of the Invention]

When automatically determining the exposure amount in this type of technology, such as the photo printing method, it is usually the RGB3 of the entire screen area.
The amount of transmitted light of the color components is controlled to be constant, so that a print with a well-balanced color balance and print quality is created. This is based on an empirical rule that in a normal shooting scene, the average reflectances of the three colors obtained by integrating the entire scene are almost constant. That is, when a general neutral neutral subject is photographed with a color negative film under a white light source, the average transmission density is excessive or insufficient of the exposure amount, the light quality of the light source at the time of photography, the sensitivity of the RGB photosensitive layer of the color negative film, the presence or absence of a mask, etc. However, these changes are absorbed by making the exposure exposure amount of RGB constant during printing, and a good print can be obtained.

On the other hand, when the color distribution of the subject deviates from the statistical average, the energy distribution of the light reflected by the subject is also not RGB constant, so that the three colors of the color negative film generated in that case. The concentration change of can not be correctly controlled by the above method. In addition, when the brightness configuration is extremely biased compared to the normal brightness distribution, such as when there are extremely high brightness areas or extremely high low brightness areas compared to normal scenes, the density of the negative film Since the change is due to the area change of the density of the subject, it cannot be corrected by the method of controlling the printing exposure amount only by the average transmission density. Similarly, even when the main subject constitutes a shadow portion or an extreme highlight portion as compared with surrounding subjects, the setting conditions of the printer are largely different and correction cannot be performed. As a method of determining the printing exposure amount for solving such a problem, a negative screen is divided into individual image information characteristic values as in JP-A-56-23936 and JP-B-56-2692, and the obtained image information characteristic values are obtained. There is a method of obtaining an appropriate exposure amount for the scene from the respective divided screen information characteristic values. For example, as an example, when the average transmission density of the entire screen is D _a , the maximum density of the entire screen is D _max , and the average density of the central part of the screen is D _center , the exposure amount X ₁ of the 135 F size film is X ₁ = a ₁ · D _a + b ₁ · D _max + c ₁ · D _center + D ₁ (1), the exposure amount X ₂ of 110 size film is X ₂ = a ₂ · D _a + b ₂ · D _max + c ₂ · D _center + D ₂ …… (2) If you prepare a correction formula X _s such as X _s = K _i + K _j · X (3) for each film size with respect to the exposure amount X obtained in this way, it will correspond to the size. It is possible to print a negative film with the exposure dose X _s corrected correctly. Where the coefficients a ₁ , b ₁ , c ₁ , D ₁ , a ₂ ,
_{b 2, c 2, D 2} , K i, K j are those defined in advance by experiment or the like for each film size.

In addition, instead of measuring the image information characteristic value for the divided area of the desired shape from the beginning, the screen is made two-dimensional by an image sensor such as CCD or photodiode array.
Desirably, the image information characteristic values such as the density or the transmittance are measured for each pixel by substantially evenly dividing, and the characteristic information for each divided area is obtained by appropriately combining the characteristic values for each pixel based on the shape of the screen division. It is possible to obtain, and the exposure amount can be determined using the characteristic information.

Therefore, when the amount of exposure is determined or the amount of exposure is corrected based on the information from the divided areas by dividing the screen as described above, how to divide the screen becomes a problem. If the division is different due to the difference in the original image film format such as the difference in film size printing direction, there is a problem that the arithmetic processing becomes complicated. The problem is that the image information captured in pixel units does not depend on the format of the original image once so that the number of classification areas and the positions of the divided screens can be made to correspond one-to-one even when different original images are between formats. The problem can be solved by classifying and re-arranging in the format of. However, in this case, it has been difficult with the prior art to easily and efficiently classify various original picture formats into intermediate formats.

[Object of the Invention]

The present invention has been made as a result of considering the above points, and with a simple configuration, it can flexibly correspond to various formats of an original image such as a film, and efficiently, and thus at high speed, an image of the original image of a negative film or the like. It is an object of the present invention to provide an image exposure method in which information is detected accurately and in detail, and the exposure amount is automatically determined according to the image information of the original image.

[Structure of Invention]

The present invention relates to an image exposure method for automatically determining an exposure amount such as printing and / or an exposure correction amount,
Image information including an original image on a color negative film is divided into a plurality of pixels, a characteristic value obtained in pixel units is detected, and a characteristic value of a virtual pixel corresponding to the characteristic value is stored based on a classification table stored in advance. Determined from the characteristic value of the pixel,
In the image exposure method of determining the exposure amount and / or the exposure correction amount based on the characteristic value of the determined virtual pixel, the classification table gives a label for identifying the virtual pixel corresponding to the pixel, The area is divided into a smaller number of areas than the number of pixels, and the same label is given in each area.

In the present specification, a split screen of an intermediate format that does not depend on the format of the original image is a virtual screen, pixels that make up the virtual screen are called virtual pixels, and the original image is split by an image sensor such as a CCD. The original pixels taken in are called physical pixels, and the screen composed of the physical pixels is called a physical screen. In general, one virtual pixel is composed of zero or more (not exceeding the maximum number of all physical pixels) physical pixels.

The label means a value written in the classification table in the same number as all the physical pixels captured by the image sensor or the like which is an image reading unit in a divided manner. (For example, if the physical screen captured by the image sensor is composed of 12 × 8 physical pixels, the classification table is also labeled with the same 12 × 8 size, as shown in the examples below.) The image information in the present invention can be read by photoelectrically converting the reflected light or transmitted light of the original image and using an image sensor such as a CCD.

In the present invention, the exposure amount and / or the exposure correction amount are determined based on the image information, but there are cases where the exposure amount is determined only by the image information and cases where the conventionally used LATD control method is used in combination.

The classification table according to the present invention is used for a classification means for converting a physical pixel set into a virtual pixel set, and should be in a table format having a shape capable of reproducing a state in which an original image is divided into screens for each pixel. Is a means of facilitating arithmetic processing.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. The examples described below are examples of the present invention, and the present invention is not limited thereto.

In this embodiment, the following method is adopted. That is, the information including the original image on the color negative film is divided into a plurality of pixels on the screen, the characteristic value obtained for each pixel is detected, and the characteristic value of the virtual pixel (here, based on the classification table stored in advance). In the image exposure method, the light intensity) is determined from the characteristic value of the corresponding pixel, and the exposure amount and / or the exposure correction amount is determined based on the determined characteristic value of the virtual pixel. A label for identifying a virtual pixel is provided corresponding to, and the area is divided into a smaller number of areas than the number of pixels (areas corresponding to the sections indicated by broken lines in FIGS. 1A and 1B). In the area, the same label is given.

In this embodiment, as understood from FIGS. 1A and 1B, the divided areas of the classification table are formed such that the central area is wider than the peripheral area.

In the present embodiment, the image information of the negative film used as the original image is divided into screens, and various methods are conceivable as a method for measuring and detecting the characteristic value in pixel units, for example, an image of a CCD using a light receiving element. It can be easily detected by using a sensor (one-dimensional or two-dimensional) (Japanese Examined Patent Publication No. 56-2691 and Japanese Examined Patent Publication No. 60-177337).

The above characteristic values are based on the original image (for example, negative film).
It is image information detected for each physical pixel by an image sensor using a CCD, which means light intensity in this embodiment, but may be transmittance or density.

To classify the screen-divided pixel set into a virtual pixel set using a predetermined classification table means to use a classification table in which the characteristic values detected in physical pixels are created in advance for each image size. Then, it is quickly replaced with an intermediate format (here, a virtual pixel set) that does not depend on the size and / or the printing direction of the original film, so that the difference due to the film size and / or the printing method is absorbed. Is done for.

The above description will be specifically described below.

_Denoting the light intensity at the i-th row and the j-th column of the negative film captured for each physical pixel by the image sensor as DN _ij , a classification table as shown in FIG. 1 (a) is prepared in advance. The classification value of DN _ij (that is, the coordinate value of the virtual pixel) can be obtained by simply referring to the i-th row and the j-th column of the classification table. The classification table gives a label for identifying a virtual pixel corresponding to the pixel. Here, specifically, values (labels) are written (assigned) by the same number as all the physical pixels captured by the image sensor in a divided manner. That is, for example, as shown in FIG. 1A, the physical screen captured by the image sensor is 12 × 8.
If the classification table has the same size of 12 × 8, the classification table is prepared.

Further, the classification table is divided into a smaller number of regions than the number of pixels, that is, the broken-line regions shown in FIGS. 1 (a) and 1 (b). The same label is given to each area (broken line portion). That is, one label or a plurality of labels are given to this area corresponding to the original pixels, and one kind of label is given to this one area (FIG. 1A).
(See (b)). In this example, the classification table is created on the assumption that the virtual screen is composed of 4 × 4 16 pixels. The classification table contains 0 and integers from 1 to 16. Here, the physical pixel corresponding to the position where the value of the classification table is n (1 ≦ n ≦ 16) is classified into the nth virtual pixel. However, the physical pixel corresponding to the position where the value written in the classification table is 0 means that the corresponding virtual pixel does not exist, and is invalid data and is ignored in the processing. For example, assuming that FIG. 1A is a classification table for a 110-size negative film, when classifying pixels of a 110-size negative film, the classification value of the pixels in the third row and fourth column is 1, The classification value of the pixel in the fourth row and fifth column is 6. Therefore, with respect to all the characteristic values taken in for each pixel, it is possible to easily associate the virtual pixels with each other by referring to the classification table in which the physical pixels are in one-to-one correspondence. High-speed classification is possible. Further, when the negative film formats are different, for example, in the case of 135F size, it is possible to perform the same classification by preparing a classification table as shown in FIG. 1 (b)).

In this way, when printing a plurality of negative film formats, it is possible to make the classification method the same by preparing a plurality of classification tables, and the processing after conversion to virtual pixels is The processing is easy because they can be exactly the same. It is not always necessary to prepare a classification table for every negative film format.

Further, it is possible to achieve the same technical idea without necessarily using a classification table having the same size as the physical screen. Two examples will be given below.

As a first example, when the classification table of FIG. 1 (a) is desirable, the minimum row and column values in which a classification table other than 0 is written as the classification table value and the maximum row and column values Of the values and the original classification table, only the part in which a non-zero value is entered may be prepared.

This row is shown in FIG. 2 (a). In this case the smallest row value
R _min, the maximum value of values the value of R _max minimum column of C _min maximum column line when the C _max, classification value V _ij for DN _ij is Required by. However, 0 in the classification table means that there is no virtual pixel corresponding to the physical pixel. In this case as well, conversion to a virtual screen is performed in the same classification procedure by preparing a plurality of classification tables for different formats of negative film.

As another example, when the classification table of FIG. 1 (a) is desirable, as shown in FIG. 2 (b), the classification table is retained in a decomposed form in a row direction and a column direction. You can do it. The classification table of FIG. 2 (b) can be easily reproduced by performing the following calculation. After the reproduction, the same image processing can be performed, and the classification table can be stored with a small storage capacity.

Here, the classification table in the row direction and the classification table in the column direction can be obtained by the following means. For example, in this example,
Since the virtual screen is composed of 4 × 4, the classification value V _ij takes values from 1 to 16 and 0. Here, the following calculation work is performed.

Using U _ij thus obtained, the row classification table R _i and the column classification table C
ask _j However, mod means the remainder, and div means the integer division (the remainder is cut off).

To use the row classification table and column classification table obtained in the above procedure, The classification value is uniquely obtained from the row and column coordinates _ij by performing the calculation.

By adopting this method, the classification table can be stored with a small storage capacity, and when used, the original classification table can be easily derived by calculation.

Further, the configuration of the classification table is not limited to the above example, and generally, any configuration can be considered as long as it involves a mapping unit that uniquely finds the coordinates of the virtual pixel based on the coordinate information of the physical pixel. To be For example, the classification table is decomposed into a row classification table and a column classification table, and the non-zero portion and the non-zero
It is also possible to retain the values of the first row and column of and the values of the last row and column of as a classification table. Alternatively, the same effect can be obtained by holding the values of the first row and column, the number of non-zero elements in the row, and the number of non-zero elements in the column.

Each of the above-mentioned methods has advantages and disadvantages, and which method is adopted is arbitrary, but can be appropriately selected according to the storage capacity of the computer, the calculation speed, the target of information processing, and the like.

Next, as a method for obtaining an information group for each virtual pixel unit from the characteristic value detected in pixel units by dividing the original image such as the negative film, screen division is performed for the intermediate format as in the conventional technique. It is performed again and is performed by extracting a feature amount (for example, an average value, a maximum value, a minimum value, etc. of characteristic values) from the subdivided screen. Specifically, the exposure amount determining formulas (1) and (2) for each film size are standardized as, for example, X = a · Da + b · D _MAX + c · D _MIN + Dd (4) For each virtual pixel, it is not possible to obtain the image information of the split screen common to each film size by using a method such as obtaining the characteristic value of the physical pixel included in the virtual pixel. The feature amount for each virtual pixel can be easily calculated from the data of the physical pixel by such calculating means.

The method for determining the printing exposure amount and / or the exposure correction amount for an original image such as a negative film using at least a part of the information group obtained by the above method is a feature for each virtual pixel obtained by the above method. The exposure amount for the original image is determined by substituting the exposure amount into a common exposure amount determination formula. Specifically, the exposure amount X is obtained from the above equation (4) for negative films of various sizes conveyed to the printing section. Further, the exposure amount X can be corrected according to the size according to the above formula (3).

According to the present embodiment, since the memory used can be reduced, the structure can be further simplified. Furthermore,
It is possible to realize higher speed calculation (speed up).

〔The invention's effect〕

As described above, according to the present invention, it is possible to detect image information of an original image accurately and in detail at high speed effectively while flexibly supporting various formats of the original image with a simple configuration such as reduction of used memory. Therefore, image printing can be performed with an appropriate exposure amount according to original images of various sizes.

[Brief description of drawings]

FIGS. 1 (a) and 1 (b) are explanatory views of a classification table having different film sizes in the embodiment of the present invention, and FIG. 2 (a).
And (b) are explanatory views showing a storage means of a simpler classification table.

Continuation of the front page (56) Reference JP 60-177337 (JP, A) JP 60-72075 (JP, A) JP 61-244174 (JP, A) JP 59-205874 (JP , A) JP-A-57-58462 (JP, A)

Claims (1)

[Claims] 1. Image information including an original image on a color negative film is divided into a plurality of pixels on a screen, a characteristic value obtained for each pixel is detected, and an image characteristic value of the original image is calculated from the characteristic value. In an image exposure method for determining an exposure amount and / or an exposure correction amount based on an image characteristic value, a classification table storing labels for pixels corresponding to a screen of the original image among the pixels, and According to the label, the classification table is divided into a predetermined number of regions smaller than the number of pixels, and each of the pixels is associated with the region according to the label, and the region characteristic value relating to the region is determined. Calculating the characteristic value of the pixel corresponding to the area by performing a predetermined calculation, and calculating the image characteristic value of the original image based on the characteristic value of the area. Image exposing method according to claim.