JP2683792B2 - How to determine the exposure of photographic printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention measures the transmission density of an original image of a negative film or the like, and based on the two-dimensional image information obtained from that information, an appropriate printing exposure amount and / or Alternatively, the present invention relates to a method for determining a photoprint exposure amount for determining an exposure correction document.

[Background of the Invention]

When an original image such as a negative film is printed on a photosensitive material such as photographic paper, the printing conditions are not the same depending on the original image. The amount of transmitted light (transmitted density) of the original image is measured for each frame of the negative film, and the exposure time (exposure amount) at the time of printing is determined based on the information. In the case of a color negative film, the transmitted light of the original image is separated into three colors, the amount of transmitted light of each color separated light is measured, and the exposure conditions during printing are determined.

In the conventional automatic photographic printing apparatus, the following method is adopted to obtain information for determining the appropriate printing conditions.

(1) LATD (Large Area Transmitt
ance Density) measuring method A photometric device consisting of a photosensor such as a photodiode is provided in a place not in the optical path of the printing optical system that forms an image on the printing paper from the negative film, and the exposure amount or exposure is based on the average transmitted light amount of the entire original image. Although it is a method to determine the correction amount, it is too macro information, so if you try to determine the printing conditions only with this information, it is not effective for any negative film frame, In, it is known as an empirical rule that it is effective for about 60% to 70% of pieces.

(2) Area-division photometric method The image density detection by the LATD measurement is to measure the density of the original image evenly, and not to accurately measure the density information for printing the original image. In order to solve the above-mentioned drawbacks of the LATD photometric method, the original image screen is divided into upper, lower, left, and right sections for photometry, and an appropriate printing exposure amount is determined based on the obtained two-dimensional image information. For example, Japanese Patent Publication No. 56-2691) is used.

In general shooting (normal shooting), since the sky is above and the ground is below, and the lighting is sky, the highlight is blue sky, that is, the blue density is high, so it is possible to determine whether the image is upside down with a high probability. Also, the exposure amount for exposure or the correction amount is determined by performing classification by focusing on the fact that there is a high probability that vertical density is higher in the density difference between the left and right sides than the difference in density between the upper and lower sides. Although it is possible to discriminate the upright information of the image by this method, there is a problem that an appropriate printing exposure amount cannot be obtained if the discrimination is incorrect. Further, the fact that the positive or negative direction of the image of a negative film or the like is not uniform, and factors that make it difficult to distinguish the positive and negative information are (a) that the direction of insertion of the negative film during printing is not constant, and (b) the film There is a camera in which the loading direction that winds up the film is reversed, (c) In vertical shooting, the shutter position may be above or below, and (d) the film size is 135F Size and 135H size, or E size and 2E size prints are different in the direction of film use, such as when they are obtained from photographic paper of the same width.

Also, in the case of a scene having a background brightness higher than that of the main subject, for example, a snow scene, the low density of the central portion represents the main subject in many cases, and a scene in which the main subject has high luminance, for example, flash photography, The highest negative density in the center of the image represents the main subject. For such an image, the image densities of the center and peripheral parts are stochastically compared and classified,
Although it is possible to determine the exposure correction amount, there is a problem that a proper printing exposure amount cannot be obtained if misjudged.

[Object of the invention]

The present invention has been made as a result of considering the above problems, and it is possible to determine an appropriate exposure amount and / or an exposure correction amount according to each original image by rearranging and organizing two-dimensional image information on a screen. An object of the present invention is to provide an image exposure method that can be performed.

[Configuration of the invention]

The present invention relates to a photographic printing exposure amount determination method, in which an original image recorded on a color negative film is divided into a plurality of pixels and read, and an exposure for printing the original image on a photographic light-sensitive material based on the obtained image information. In the method of determining the exposure amount for photographic printing, the characteristic values of each pixel derived from the image information are collected, the statistical values are used, and these characteristic values are rearranged and arranged according to a predetermined procedure. The feature is that the amount or the exposure correction amount is determined.

The original image in the present invention means a transparent image,
Examples include images recorded on reversal film or negative film. For the light-sensitive material of the present invention, for example, color photographic paper or the like can be used.

Further, the rearrangement and rearrangement in the present invention is to replace the positional relationship of each pixel information, regardless of the image structure of an image of a main subject or the like, of pixels or pixel sets forming an image or statistics thereof. .

Further, in the present invention, the exposure amount and / or the exposure correction amount is determined based on the rearranged and arranged two-dimensional image information.
There are a case where the exposure correction amount is determined only by the two-dimensional image information and a case where the conventionally used LATD exposure control method is used together. Two-dimensional image information can be read using an image sensor such as a CCD.

〔Example〕

FIG. 4 is a schematic block diagram of an automatic photographic printing apparatus that employs the photographic printing exposure amount determining method according to the present invention. The constituent elements will be described below.

Reference numeral 1 denotes a light source such as a halogen lamp for printing, which is turned on by a stabilized constant voltage power source of direct current or alternating current. The light emitted from the light source 1 is totally reflected by the elliptical mirror 2, the visible light portion is reflected by the cold mirror 3, emitted downward from the opening 2A of the elliptic mirror 2, and transmitted through the heat insulating glass 4 so that the light source portion is formed. To form. Reference numeral 5 is a light control filter unit. The light passing through the light source unit is changed by the maker of the negative film to be printed by the dimming filter unit 5 in which a plurality of filters are put in and out in the optical path, the change in the light component of the negative transmitted light due to the film type, Or, it is selected to correct and absorb changes in the light quality of the light from the light source over time, reduce the difference between the wavelength distribution of the light source section and the sensitivity distribution of the negative film, and minimize the difference in the exposure time of each color. There is. 6 is a cut filter unit. The cut filter unit 6 is configured such that the cut filters of respective colors are put into and taken out of the optical path by the drive motors M ₁ , M ₂ and M ₃ , and the cut filter unit 6 adjusts the color balance of the screen frame of the negative film when the color balance is lost. Light correction is performed, and the wavelength of a predetermined region is cut according to the exposure time required for each color.

Reference numeral 7 is a diffusion unit. The inner surface 7A of the diffusing section 7 has a prismatic shape made of a glossy material, and is a diffusing plate such as ground glass.
The light source light, which has become scattered light by 7B, is diffused and mixed while being reflected on the inner surface 7A of the diffuser 7 having a tunnel shape, and uniformly illuminates the original image on the negative film.

Reference numeral 8 denotes a negative mask, which holds the original image F of the negative film and covers the peripheral portion undesired for printing.

Reference numeral 9 denotes a lens, which magnifies and projects the real image of the original image F onto the photosensitive material (color paper) P.

Reference numeral 10 denotes a photometric means, which is fixed outside the optical path for photographic printing and measures the amount of transmitted light of the entire original image F. As an example of the photometric means 10, in FIG. 4, an image sensor such as a CCD is obliquely arranged outside the optical path, and the transmitted light of the original image F is obliquely received and photoelectrically converted. In addition to this, a means for inserting a semitransparent mirror into the optical path and spectrally measuring a part of the light flux and a photometric means using a variable light-shielding plate are also used.

What has been described above is the same as that used in a normal photo automatic printing apparatus. The present invention relates to a method for determining a photographic printing exposure amount of an original image F for performing this photographic printing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a flow chart of an embodiment in which the method for determining the exposure amount for photographic printing of the present invention is adopted.

In this embodiment, a color negative film is used as an original image F, and image information on the negative film is read by irradiating the color negative film with light, and the image of the negative film is projected onto a photosensitive material and exposed to light. In the determination method, the image information of the original image F is photoelectrically converted and read by the photometric means 10 which is an image sensor such as a CCD.
The two-dimensional image information is obtained, and the two-dimensional image information is obtained according to the image information.
The three-dimensional image information is rearranged and rearranged, and the exposure amount and / or the exposure correction amount is determined from the rearranged result. Also,
The two-dimensional image information is a characteristic value of each pixel set obtained by photoelectrically reading the original image F using an image sensor such as a CCD and dividing the screen into a plurality of pixels. The intensity or the density or transmission density of the original image F.

As one of the pixel information for rearranging and organizing,
It is possible to use a method of calculating the sum or average value of the pixel information of the two-dimensional image in the row direction and rearranging all the pixels forming the corresponding row in the ascending or descending order in accordance with the calculation result.

For example, as shown in FIG. 2 (a), the original image F is 4 ×
When the screen is divided into 16 pixels of 4, the sum or average of pixel values is calculated for each row as shown in FIG. 2 (b), and then ascending order of power as shown in FIG. 2 (c). Sort by row.

The numerical value in each pixel is 0 to 25 when the measured characteristic value of each pixel of the original image F, for example, the transmission density value is converted into an 8-bit value.
It is given a number of 5.

Further, the number of surface divisions (number of pixels) of the pixel F is 4
In addition to × 4, it is also possible to select 12 × 8, 16 × 16 or 40 × 30.

By using this image information, the row pixel set forming the main highlight part of the image is transferred to the upper part of the image, so that the image is upright / inverted, and the highlight part is in the front or back of the image. The image density information can be easily made uniform regardless of the above.

Further, for the vertically captured original image, first, after rearranging in the row direction, rearranging in one direction in the column direction to ascending or descending power in the same manner as in the method of operating in the row direction. Can be made uniform.

As an example of the method of determining the exposure amount or exposure correction amount of the photographic image based on the rearrangement result of the image information, for example, as shown in FIGS. 3 (a) and 3 (b), upper, lower, left, right , Divide the image in the center, calculate the average, maximum, minimum density, etc. of each, and collect the data,
By statistically processing and substituting the values for the parameters, focusing on the average density, the obtained characteristic values are rearranged and compared to determine an appropriate printing exposure amount.

In the rearrangement result, the two-dimensional information as the image structure is lost, but the density information of the image can be handled uniformly regardless of the upright / inverted image of the original image.

The exposure amount, that is, the exposure time Td is represented by the following general formula.

Td = f (D) + f (cv) + ... + f (z) ... (1) In the formula (I), f (D) is obtained as a function of the average transmission density D, and f (cv) is a statistic. Exposure correction amount
It is obtained as a function of cv, and is also obtained as a sum total value of the function f (z) of other correction elements (here, z) in addition to these functions.

Here, as the exposure correction amount cv, the correction amount for the exposure time Td is calculated by the maximum density in the central part, the minimum density in the central part, the average density in the central part, and the densities in the upper, lower, left and right divided areas. The correction amount is determined by the following formula.

However, i is a label showing each image area, Xi is a parameter represented by the density in each image sub-area such as the central average density, Ci is a coefficient, and b is a constant. Then, these coefficients / constants can be obtained by a statistical means that analyzes a large amount of original images.

In this embodiment, the pixels are rearranged, but the representative parameters obtained in each image sub-region can be applied. For example, in FIG. 3, the values are replaced with respect to parameters having symmetry in the vertical and horizontal directions, such as image sub-regions D2 and D3 and D4 and D5. That is, the average, maximum, and minimum densities, which are representative parameter examples for each image sub-region, are
Let ave, Dimax, Dimin, i be the labels of each image sub-region.

An example in which parameter substitution is performed focusing on the average density is shown below.

if (D2 ave> D3 ave) then begin swap (D2 ave, D3 ave); swap (D2 max, D3 max); swap (D2 min, D3 min); end; if (D4 ave> D5 ave) then begin swap (D4 ave, D5 ave); swap (D4 max, D5 max); swap (D4 min, D5 min); end; Here, the function SWAP () is a function for exchanging the values of two arguments.

Regarding the parameters after such replacement, (1),
The proper exposure amount is determined from the equation (2).

By rearranging and arranging the original image information as described above, it is possible to determine an appropriate exposure amount and / or exposure correction amount by comparing with the conventional estimation method of the upright information and the estimation method of the main highlight part of the image. Became.

〔The invention's effect〕

As is clear from the above description, by using the method for determining the photographic printing exposure amount of the present invention, it is possible to adjust the properness according to each original image regardless of the position of the upright / inverted image of the original image and the main highlight portion of the image. It is possible to determine a proper exposure amount and / or exposure correction amount.

[Brief description of the drawings]

FIG. 1 is a flow chart of an image exposure system according to the present invention, and FIGS. 2 (a), (b), and (c) are explanatory views showing an operation example of rearranging the pixel values of each pixel by dividing the original image into planes. 3 (a) and 3 (b) are explanatory views of another embodiment to which the present invention is applied, and FIG. 4 is a schematic configuration diagram of a photo automatic printing apparatus according to the present invention. 10: Photometric means F: Original image P: Photosensitive material

Claims (1)

(57) [Claims] 1. A photographic printing exposure amount determination for dividing an original image recorded on a color negative film into a plurality of pixels, reading the image, and determining an exposure amount for printing the original image on a photographic light-sensitive material based on the obtained image information. In the method, collecting the characteristic values of each pixel derived from the image information, using the statistics, rearranging and rearranging these characteristic values according to a predetermined procedure, and determining the exposure amount or exposure correction amount from this rearrangement result. A method for determining a photoprinting exposure amount, characterized by: