JPH01195439A - Method for exposing image - Google Patents

Abstract

PURPOSE:To determine an appropriate exposure and/or an exposure correcting quantity in accordance with respective original images by replacing and arranging the two-dimensional image information of a screen. CONSTITUTION:In case of dividing the original image F into 16 elements of 4X4 on the screen, the sum or the mean value of the picture element values is calculated every row and the calculated values are replaced in ascending powers every row. Now, numerical values in the respective picture elements are obtained by converting the measured specific values of the respective picture elements of the original image F, for example, transmissive density values, into the values of eight bits and adding the numbers of 0-255 to them. Since the concurrence of the picture elements of the row constituting the main highlight part of an image is thus replaced to the upper part of the image, the appropriate exposure and/or the exposure correcting quantity in accordance with the respective original images can be determined without depending to the normal/inverted image of the original image and the position of the main highlight part of the image.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention measures the transmission density of an original image such as a negative film, and determines the appropriate printing exposure amount and/or Or it relates to an image exposure method for determining an exposure correction amount.

[Background of the invention]

When printing an original image such as a negative film onto 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 negative film, and the exposure time (exposure amount) during printing is determined based on this 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 for printing are determined.

In conventional automatic photo printing apparatuses, the following method is employed to obtain information for determining appropriate printing conditions.

(1) LATD (Total area average transmission density Large A
reaTranso+1ttance Density
)Measurement method A photometric means consisting of a light sensor such as a photodiode is installed in a location that is not in the optical path of the printing optical system that forms an image from the negative film onto the photographic paper, and the exposure amount or exposure is determined based on the average transmitted light amount of the entire original image. This method determines the amount of correction, but since the information is too macroscopic, if you try to determine the printing conditions based only on this information, it will not be effective for every frame of negative film, and it will not be effective for general subjects. It is known as a rule of thumb that it is effective for about 60% to 70% of the pieces.

(2) Plane-divided photometry Image density detection by LATD measurement measures the density of the original image on an average basis, and does not accurately measure the density information for printing the original image. Above LA
TD photometry In order to solve the photometering point, a method of dividing the screen of the original image into sections such as top, bottom, left and right, and measuring the light, and determining the appropriate printing exposure amount based on the obtained two-dimensional image information,
(For example, Japanese Patent Publication No. 56-2691) is used.

In general photography (straight shooting), the sky is above and the ground is below, and since the lighting is the sky, the highlights are blue sky, that is, the blue density is high, so there is a high probability that the image will be correctly or inverted. In addition, the classification was carried out by focusing on the fact that images with a higher density difference between the left and right sides than the difference between the upper and lower sides are more likely to be vertical shots, and the amount of exposure or correction for burn-in was determined. Although it is possible to determine the normal and inverted information of an image using this method, there is a problem in that if the determination is incorrect, the exposure amount for proper printing cannot be obtained. Furthermore, the normal and inverted directions of images such as negative films are not uniform, and the factors that make it difficult to distinguish normal and inverted information are: (a) The insertion direction of the negative film during printing is not constant; (b) ) There are cameras that wind the film in the opposite loading direction, (c) When shooting vertically, the shutter may be in the upper or lower position; (d) Even when shooting horizontally, the film size does not change. , 135
F size and 135H size, or E size and 2E size
For example, there are differences in the direction in which the film is used, such as when a size print is obtained from the same width of photographic paper.

In addition, in scenes where the background brightness is higher than the main subject, such as a snow scene, the low density in the center often represents the main subject, and the scene where the main subject has high brightness,
For example, in the case of flash photography, the highest density of the negative at the center of the image represents the main subject. For such an image, the image density of the center and the periphery can be classified probabilistically and compared to determine the exposure correction amount, but if the judgment is incorrect, the exposure amount for proper printing will not be obtained. There's a problem.

[Purpose of the invention]

The present invention was made as a result of taking the above problems into consideration, and it is possible to determine the appropriate exposure amount and/or exposure correction amount according to each original image by rearranging and organizing the two-dimensional image information on the screen. The purpose of this invention is to provide an image exposure method that can be used.

[Structure of the invention]

The present invention relates to an image exposure method, in which an original image is irradiated with light, image information on the original image is read, and then the original image is projected onto a photosensitive material and exposed. The image information on the image is divided into a plurality of pixels, the light amount is measured for each pixel, two-dimensional image information of the original image is obtained by the light amount measurement, and the pixels are rearranged and arranged according to the image information. The method is characterized in that after determining the exposure amount and/or the exposure correction amount from the sorting results, uniform exposure is applied to the original image and the original image is printed onto a photosensitive material.

Note that the original image in the present invention refers to a transparent image, such as an image recorded on a reversal film or a negative film. For example, color photographic paper can be used as the photosensitive material of the present invention.

In addition, rearranging in the present invention means replacing the positional relationship of each pixel information of pixels, pixel sets, or their statistics constituting an image, regardless of the image structure as an image of the main subject, etc. .

Furthermore, in the present invention, the exposure amount and/or the exposure correction amount is determined based on the rearranged two-dimensional image information. 2
There are cases in which the exposure correction amount is determined only by dimensional image information, and cases in which the conventionally used LATD exposure control method is used in combination. Two-dimensional image information can be read using an image sensor such as COD.

〔Example〕

FIG. 4 is a schematic diagram of an automatic photo printing apparatus according to the present invention. The constituent elements will be explained below.

(2) is a light source such as a halogen lamp for burning, and is lit by a stabilized constant voltage DC or AC power source.

The light emitted from a light source 1 is totally reflected by an elliptical mirror 2, the visible light part is reflected by a cold mirror 3, and is emitted downward from two openings of the elliptical mirror 2, and is transmitted through a heat-insulating glass 4. 5
is a dimming filter section. The light passing through the light source section is changed by the light control filter section 5 in which a plurality of filters are put in and taken out in the optical path, and the light component of the negative transmitted light changes due to the manufacturer and film type of the negative film to be printed. Or, it is selected to correct and absorb changes in the light quality of the light source over time, reduce the difference between the wavelength distribution of the light source and the sensitivity distribution of the negative film, and minimize the difference in exposure time for each color. There is. 6 is a cut filter section.

The cut filter unit 6 is driven by a drive motor M , , M =,
A cut filter for each color is moved in and out of the optical path using M, and the light control is corrected for the out of color balance of the frame of negative film, and the cut filter is adjusted according to the exposure time required for each color. , cuts wavelengths in a predetermined region.

7 is a diffusion section. The interior surface 7A of the diffusion section 7 has a prismatic shape made of a glossy material, and the light source light scattered by the diffusion plate 7B, such as frosted glass, is reflected on the interior surface 7A of the diffusion section 7, which is laminated and has a tunnel shape. while being diffused and mixed, uniformly illuminating the original image on the negative film.

8 is a negative mask which holds the original image F of the negative film and covers the peripheral portions which are not desirable for printing.

A lens 9 enlarges and projects the real image of the original image F onto a photosensitive material (color paper) P.

1O is a photometric means, which is fixedly installed 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 IO, shown in FIG. 4, an image sensor such as a COD is disposed obliquely outside the optical path, and the transmitted light of the original image F is received obliquely and photoelectrically converted. In addition, a means for measuring light by inserting a semi-transparent mirror into the optical path and separating a part of the light beam, and a means for measuring light using a variable light shielding plate are also used.

What has been explained above is the same as that used in ordinary automatic photo printing apparatuses. The present invention relates to an image exposure method for the original image F that performs this photographic printing.

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure shows a flowchart of an embodiment of the invention.

This embodiment is an image exposure method in which a color negative film is used as the original image F, image information on the negative film is read by irradiating it with light, and the image of the negative film is projected onto a photosensitive material and exposed. The image information of the negative film is photoelectrically converted and read by an image sensor such as COD to obtain two-dimensional image information, and the two-dimensional image information is rearranged and organized according to the image information, and the exposure amount and /or determines the amount of exposure correction. The two-dimensional image information is a characteristic value of each pixel set obtained by photoelectrically reading the original image using an image sensor such as a COD and dividing the screen into a plurality of pixels. Related to image density or transmission density.

As one of the image information for sorting and organizing the above, 2
It is possible to calculate the sum or average value of the pixel information of a dimensional image in the row direction, and to rearrange all the pixels constituting the corresponding row in ascending or descending power order according to the calculation result.

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

Note that the numerical value in each pixel is determined by converting the measured characteristic value of each pixel of the original image F, for example, the transmission density value, into an 8-bit value, ranging from 0 to 25.
50 number has been assigned.

In addition, the number of plane divisions (number of pixels) of the original image F is 4 above.
In addition to ×4, 12X 8.16X 16 to 40X3
It is also possible to select 0.

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

Furthermore, for vertically shot original images, first rearrange them in the row direction, and then rearrange them in ascending or descending powers in one direction in the column direction in the same way as the method used in the row direction. It becomes possible to standardize the

As an example of a method for determining the exposure amount or exposure correction amount for photographic image printing based on the rearrangement results of the image information, for example, as shown in FIGS. 3(a) and (b), The exposure amount for proper printing is determined by dividing the image into the right side and center, calculating and comparing the average, maximum, minimum density, etc. of each.

In the above rearrangement result, two-dimensional information as an image structure is lost, but image density information can be handled uniformly regardless of whether the original image is a normal or inverted image.

The exposure amount, that is, the exposure time Td is expressed as the following general formula.

Td −r(o)+f(cv)+f(z)
・Il) In this formula (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 in addition to these functions, It is obtained as a summation value of functions f(z), etc. of other correction elements (in this case, 2).

Here, the exposure correction amount cv is calculated for the exposure time Td based on the center maximum density, the center minimum density, the center average density, and the density in the upper and lower and left and right divided areas. The amount of correction is determined by the following formula.

cv-Σ Ci*Xi + b - (2) w l where i is a label indicating each image region, Xi is a parameter represented by the density in each image sub-region such as the center average density, C1 is a coefficient, and b is a constant.

These coefficients/constants can be determined by statistical means of analyzing a large number of original images.

In this embodiment, pixels are rearranged, but it is also possible to apply representative parameters determined for each image sub-region. For example, in FIG. 3, values are replaced for parameters that have vertical and horizontal symmetry, such as image sub-regions D2 and C3, and C4 and C5. That is, the average, maximum, and minimum density, which are typical parameter examples of each image sub-region, are Diave, Dimax, and Dimin, and i is the label of each image sub-region.

An example of parameter replacement focusing on the average density is shown below.

if (C2ave>C3awe) then beg
inswap (C2ave, C3ave) ;sw
ap (C2wax, C3aax); swap (
C2min, 03 m1n) ;end; if (C4awe)C5ave) then beg
inswap (C4ave, C5ave) ;sw
ap (C4max, C5max); swap (
04win, C5m1n);end;Here, the function 5WAP() is a function that exchanges the values of two arguments.

Regarding the parameters after such replacement, (1).

The appropriate exposure amount is determined from equation (2).

By sorting and organizing the original image information as described above, it is possible to determine the appropriate exposure amount/or exposure correction amount by comparing the conventional method of estimating upright and inverted information and the method of estimating the main highlight part of the image. Next time.

〔Effect of the invention〕

As is clear from the above explanation, by using the image exposure method of the present invention, it is possible to obtain the appropriate exposure amount and /or It is now possible to determine the amount of exposure correction.

[Brief explanation of the drawing]

Fig. 1 is a 70-chart of the image exposure system according to the present invention, and Fig. 2 (a), (b), and (c) show an example of operation for dividing an original image into planes and rearranging the pixel values of each pixel. Explanatory drawings, FIGS. 3(a) and 3(b) are explanatory drawings of other embodiments to which the present invention is applied, and FIG. 4 shows a schematic configuration diagram of an automatic photo printing apparatus according to the present invention. IO...Photometering means F...Original image P...Photosensitive material

Claims (4)

[Claims] (1) In an image exposure method in which an original image is irradiated with light, image information on the original image is read, and then the original image is projected onto a photosensitive material and exposed, the image information on the original image is Divide the surface into pixels and measure the amount of light for each pixel.
Two-dimensional image information of the original image is obtained by the light amount measurement, the pixels are rearranged and organized according to the image information, and the exposure amount and/or exposure correction amount is determined from the arrangement result, and then uniform exposure is applied to the original image. An image exposure method characterized by printing an original image onto a photosensitive material by giving (2) The screen-divided pixels are classified into a plurality of pixel sets each consisting of one or more pixels, and each pixel set is rearranged and organized according to the image information. An image exposure method according to claim 1. (3) The image exposure method according to claim 1, characterized in that a statistic is calculated for each pixel set, and the pixel set is rearranged and organized according to the statistic. (4) A statistic is calculated for each pixel set, the statistic of the pixel set is rearranged according to the statistic, and an exposure amount and/or an exposure correction amount is determined from the statistic. The image exposure method according to item 1.