JPS63101837A - Control method for exposure quantity of photographic printing - Google Patents

Abstract

PURPOSE:To print to correct density by deriving a density average value for executing a density control and a density average value for executing a color control, and controlling an exposure by using a functional expression in which these density average values are variables. CONSTITUTION:A CPU44 reads out three color densities of each picture element from a ROM46 and divides them into a first image area 56 and a second image area 57. From density values of each picture element contained in the area 56, a density average value is derived, and from each picture element contained in the area 57, a density average value is derived. By using these density average values, a functional expression F for controlling the density, and a functional expression Fi for controlling the color are calculated. Subsequently, an exposure quantity is calculated from an exposure quantity operational expression in which two pieces of functional expressions F, Fi are add terms. The exposure quantity which is obtained is sent to a filter adjusting part 19, and a color filter of a complementary color to the corresponding color is drawn out of a standard position, or inserted toward the center of a printing optical path 20. In such a way, the insertion quantity of color filters 16-18 to the optical path 20 is adjusted, and three color optical components of a printing light are adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photographic printing exposure control method.

[Conventional technology]

The most common photographic printing exposure control method is LATD.
This is a control method that measures the light transmitted through the entire screen of a color original image such as negative film or positive film, and logarithmically transforms this average photometric value to obtain the large area average transmission density (LAT).
According to D), red.

This controls the exposure amount of green and blue.

In addition, several improved LATD control methods have been proposed, one of which is a method that uses LATD and an image feature such as a maximum value or minimum value. Furthermore, as described in Japanese Patent Publication No. 44-827, for example, there is a method that uses the density value measured by giving a high weight to the center of the screen, and a method that automatically detects the positive skin tone part from the color original. A method has been proposed in which the basic exposure amount calculated by LATD is corrected using this skin color density. Special Public Service Showa 55729
No. 412 proposes a method of determining the image time Φ amount from a designated main image and correcting the basic exposure amount calculated by LATD. Japanese Patent Laid-Open No. 58-9136 proposes a method of using a light pen to designate one image that is recognized as the main part of a plurality of images displayed on a monitor.

[Problem that the invention seeks to solve]

The above-described LATD control method has a large effect on the low-density portion of the color original image, and the density of the printed photograph becomes low for scenes shot with a strobe light or scenes with high contrast, making it impossible to achieve a good density. Also, if the color temperature of the illumination light is low, for example when shooting outdoors in winter,
Printed in yellow or orange. This is because the LATD control method cannot distinguish between illumination light and background color.

Furthermore, in the method described above that uses image features such as LATD and maximum value, since the density value of each pixel is measured, LATD
When calculating TD, the density value of each pixel is converted into a photometric value again, the average value is obtained, and this is logarithmically converted to L.
There is also the problem that it is necessary to calculate the ATD, and this calculation takes time.

For strobe shooting scenes or scenes with high contrast, LATD cannot achieve an appropriate density, but this can be improved by using the average density value of the pixels of the entire screen instead of LATD. It is. However, if this density average value is used, in backlit scenes or when the main image exists on the shadow side, the density of the main image will become too dark. Even in this case, like the LATD control method,
The influence of illumination light cannot be removed.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photographic printing exposure control method that solves the problems that occur when using density average values and enables printing at appropriate density.

Another object of the present invention is to provide a photographic printing exposure control method that can eliminate the influence of light source color.

Still another object of the present invention is to provide a photographic printing exposure control method that allows the main image to be properly finished in color and density.

[Means for solving problems]

Generally, the main image is often located in the center of the original color image, so the exposure is controlled by calculating the average density value from pixels in the area excluding all or part of the peripheral area of the screen. By doing so, the finished density of the printed photograph will be good. That is, for density control and color control, the finish will be better if the average density values of different image areas are used. The area for controlling this color can be the entire screen as before, but
It is desirable to use the average density value at the periphery of the screen.

In other words, Evans' method is most effective for average scenery colors, because the probability that such scenery colors exist in the periphery of the screen is high.

On the other hand, there is a high probability that the color in the center of the screen deviates from the average color depending on the color of the clothes in the main image.

Therefore, the present invention divides a color original image into a first image area and a second image area, and calculates a density average value (DR, D) from the density value of each pixel included in the first image area.

.
(De, DG, I)s) and the functional formula f= (CR, Cc, C++) for controlling the color.
are calculated respectively, and the exposure NEi is calculated from an exposure amount calculation formula having at least these two functional formulas as addition terms.

Various methods can be considered for determining each image area.

For example, the first image area may include all or part of the peripheral area of the screen (
The second image area can be an area excluding the center of the screen.

Another invention calculates the average density value (Ll, LG, t, a) of pixels in a predefined color area from the first image area,
Functional formula gr for correcting color using this density average value
(LR+L, li, L, a) is calculated and added to the above-mentioned exposure calculation formula to calculate the exposure amount Ei. By using the density average value of a specific color included in the first image area, color bias caused by different types of light sources can be removed. These different types of light sources include tungsten lamp light and sunlight with a low color temperature in winter, and since these lights mainly illuminate the main image, the color of the light source appears stronger in the center of the screen than in the periphery. Because there is.

Yet another invention calculates the density average value (Pi, PG,
PM ), and from this calculate the functional formula F' (PR, Pc, Pa) to correct the density and the functional formula f'' (PR, Pc, Ps) to correct the color, respectively, and control the density. The functional formula F (Da,
Exposure IEi is calculated by adding them to the function equation f = (Cm, Cc, Cyr) for controlling color. By using this average density value of the main image, the color and density of the main image can be more appropriately finished. Here, the functional expressions F (P) and fi (P) for the main image are used in order to statistically effectively control the main images of all specified types and in all situations.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

〔Example〕

FIG. 1 shows an example of a photographic printing apparatus embodying the present invention. The white light emitted from the white light source 10 is transmitted to the diffuser tube 11. Passing through the negative carrier 12, the color original image, for example, a color negative film 13 set at the printing position, is reached.
Light this from below.

The diffusion tube 11 is a rectangular tube 14 whose inner surface is formed into a mirror surface.
and two spreaders 15 fixed to both ends thereof. A cyan filter 16 for adjusting the red component of the printing light and a magenta filter 1 for adjusting the green component are provided between the diffusion tube 11 and the white light source 10.
7, and a yellow filter 18 for adjusting the blue component.
and are arranged. The filter adjustment unit 19 adjusts each color filter 16 to
The amount of insertion into the printing optical path 20 of 18 is adjusted. For example, if the insertion amount of the cyan filter 16 is increased, the red component of the printing light will be small (therefore, the amount of red exposure will be reduced).The color negative film 13 is operated by a solenoid (not shown) during photographic printing. It is pressed down from above with the mask 21.

Above the color negative film 13 is a lens 24.
is arranged, and while the shutter 25 is open, a color negative image is formed on the color photographic paper 26. The shutter drive unit 27 opens the shutter 25 for a certain period of time to provide a standard exposure time. Further, when printing of one frame of the color photographic paper 26 is completed, the exposed part is wound up on the take-up reel 28, and at the same time, the unexposed part is taken up on the supply reel 29.
drawn from.

The mirror 32 is placed in and out of the printing optical path 20, and is inserted into the printing optical path 20 during measurement, and is retracted to the position shown by the two-dot chain line during printing. This mirror 32
The reflected light passes through the lens 33 and then enters the sensor unit 35.

This sensor unit 35 includes a lens 371, a color filter 38. The image sensor 39 outputs three color signals (red, green, blue) of each pixel of a color negative image, either independently or in a mixed state for each color. In this example, in order to reduce the cost, one image sensor is used and 25 x 25 pixels (measurement points) are used.
The three-color signal is taken out, but instead of this, it is red and green.

Three blue image sensors may also be used.

The three-color signal taken out from the image sensor 39 is converted into a digital signal by an A/D converter 40, then converted into a density signal by a logarithmic converter 41, and then sent to a microcomputer via an I10 port 42. 43. This microcomputer 43, as is well known,
I10 port 42, CPU44. RAM45. ROM4
6, and performs exposure amount calculation and control of each part, which will be described later. The RAM 45 separates the captured color density signals for each color and stores them in frame memory sections 45a to 45c.
memorize each. The keyboard 47 includes keys for controlling each part.

FIG. 2 shows an example of an image sensor. This image sensor 39 includes a photoelectric conversion section 51 for blue color in which a blue filter is arranged on the light receiving surface. A green photoelectric conversion section 52 having a green filter disposed on the light receiving surface and a red photoelectric conversion section 53 having a red filter disposed on the light receiving surface are alternately arranged in a matrix at a constant pitch. Of this matrix, 3×3 photoelectric conversion units 51 to 53 constitute a pixel measurement unit 54 for measuring one pixel of a color negative image. This pixel measuring section 54 is surrounded by a dotted line.

When reading out the signals from each photoelectric conversion section, signals of the same color within the same pixel are added and read out, or the color signals are read out in a mixed form and the microcomputer 4
3 and then perform addition within the pixel and then store it in the RAM 45. In this embodiment, since the photoelectric conversion sections of the same color are appropriately arranged in the pixel measuring section 58, the occurrence of color registration can be considerably reduced. As for the number of pixel measurement units 540, it is sufficient to have, for example, about 25 in the vertical direction and 25 in the horizontal direction.

In addition, simply, the pixel measuring section may be configured by three photoelectric conversion sections arranged in a row horizontally or vertically, or three photoelectric conversion sections forming a triangle.

FIG. 3 shows a procedure for exposure control, and the operation of the photographic printing apparatus shown in FIG. 1 will be briefly explained with reference to FIG. The color negative film 13 is transferred by a transfer means (not shown), and the frames to be printed are transferred to the negative carrier 12.
position on top of.

Since the filter adjustment unit 19 maintains the tips of the color filters 16 to 18 inserted at standard positions in the optical path 20, the white light emitted from the white light source 10 in the dimmed state is A portion passes through the color filters 16 to 18 and is sufficiently diffused by the diffusion tube 11 before reaching the color negative film 13. The light transmitted through the color negative film 13 is transmitted through the lens 24. Mirror 32. The light passes through each lens 33 and enters the sensor unit 35.

The sensor unit 35 scans the color negative image, measures the three color components of each pixel, and outputs a color signal of each pixel. This color signal is A/D converted and logarithmically converted and then stored in the RAM 45 of the microcomputer 43 in a separated state for each color.

The microcomputer 43 refers to the image area table stored in the ROM 46 and reads out the three-color density of each pixel for each area. In this embodiment, as shown in FIG. 4, the center of the screen is a first image area 56, and the area other than this is a second image area 57. Each image area 5
6.57, 30 to 70% of the entire screen is used, preferably 40 to 60%.

Next, the average density value (D, I, Da, D,
) and (C, Ca, Cm) are calculated.

As this average density value, an arithmetic mean value obtained by adding the color densities of each pixel for each color and dividing the result by the number of pixels, or an intermediate value between the maximum color density and the minimum color density, or the like is used. Substituting the density average value obtained in this way into the following exposure calculation formula,
Exposure iEi (i is red.

(representing either green or blue) is calculated.

Exposure amount calculation formula % formula %) Here, the function formula F (D, 1. Dc, Da
) uses the density average value obtained from the first image area as a variable, and is used to control the printing density.

Further, the functional expression fi (Cm, Ca, Ca) uses the density average value obtained from the second image area as a variable, and is used to control color.

As a specific example of the exposure amount calculation formula (1), the following formula is used.・Ei = D + (CRD')EG =
D + (CG-D')Ea'=D
+ (Cm-D') Here, each symbol is as follows.

ER: Red exposure amount EG: Green exposure amount EB: Blue exposure amount D= (aD,,+bDG+cDa)/(a + b
+c)D' = (aCR+bcG+cCs)/(
a+b+c) Note that a, b, and c are integers including zero, and can include up to two zeros.

In the area division shown in FIG. 4, the screen is divided into two areas, but these may be areas as shown in FIG.

In FIG. 5, areas 59 and 60 constitute a first image area, and areas 59 and 61 constitute a second image area.

Further, this first image area is an area 61 located around the screen.
The area of the entire screen excluding pixels having a specific density may be used. In this way, when the sky, foreground, and ground included in region 61 are removed and the density average value is used,
This can prevent backlit scenes from becoming too dark. Specifically, if the difference in density between two adjacent pixels on the outside and the inside is less than a certain value, the outside pixel is removed or set to a standard value (for example, the minimum density value of the screen). Pixels with a density higher than the sum of rl and OJ) are excluded.

The exposure amount Ei obtained from the exposure amount calculation formula is sent to the filter adjustment section 19, and a color filter of a complementary color to the corresponding color is extracted stepwise from the standard position or moved toward the center of the printing optical path 20. More will be inserted. As a result, the amount of insertion of the color filters 16 to 18 into the printing optical path 20 is adjusted in stages, and the three-color light components of the printing light are adjusted. The amount that cannot be corrected by the color filters 16 to 18 is sent to the shutter control section 27, which appropriately increases or decreases the exposure time of the shutter 25.

When the print key on the keyboard 47 is operated, the white light source 10 emits full light, the shutter 25 is opened for a certain period of time, and a color negative image is printed onto the color photographic paper 26. After this printing, the color photographic paper 26 and the color negative film 13 are transported by one frame. At the same time, the white light source IO is dimmed, and the filter adjustment section 19 returns the color filters 16 to 18 to the standard position in the printing optical path 20.

Thereafter, each frame recorded on the color negative film 13 can be sequentially printed onto the color photographic paper 26 in the same manner.

FIG. 6 shows a procedure for exposure control that eliminates the influence of different types of light sources. In order to eliminate the influence of this different light source, in the present invention, pixels with a specific color are extracted from the first image area, and the color correction amount is calculated using a functional formula that uses the average density value of these pixels as a variable. The basic exposure amount calculated using the exposure amount calculation formula (1) is corrected. This specific color can be defined by two-dimensional coordinates centered on a combination of two colors, as shown in FIG. 7, for example. In this example, circle 6
2 and surrounded by two straight lines 63 and 64 is defined as a specific color.

The microcomputer 43 reads the three-color density of each pixel included in the first image area, determines whether it is a specific color, and calculates the average density value (Lm
, La, Lm).

Furthermore, as mentioned above, the density average value (D
E, Da, I)a) and (CR, Ca, Cm
) and substitute them into the following exposure calculation formula to calculate the exposure amount Ei.

Exposure amount calculation formula % formula %) Here, the function formula F (D) and the function formulas f and (C) are the same as the exposure amount calculation formula fl) described above. Functional formula g=
(LR, LG, Lm) are for correcting the light source color.

The coefficients, , and are determined by experiment. For example, when g=O, 'C+ = 1.0 kt 0.0g,
When ≠O, k+ = 0.5 kg = 1.0 is used. Further, when the number of pixels of f, , g is small, all three colors may be set to O.

Specific examples of the exposure N calculation formula (2) include the following.

ER=D++(CRD')+l(t(L-
D")Ea =D++(c(i-DI)+k
t (t,a −D”)El =D++(Ca
D')+l(! (t, m D'') Here, D and D'' are the same as the exposure calculation formula (1). D''
is as follows.

D”= (aL, I+bLc+cLm)/(a+b
+c) Note that a, b, and c are integers including zero, and can include up to two zeros. Further, for D'', an average value of a large number of pixels can be used.

In the embodiment described above, the density average values (CII, Cc, Cs
) is calculated. Instead of this, for example, define a color that falls within the Ueda 62 in FIG. 7, extract pixels with this color from the second image area, and calculate the density average value (CR, Cc, Cm) from these pixels. may be calculated. This makes it possible to prevent color feria from occurring due to bright colors in the background.

Generally, if the main image has a good finish, it is often considered that the print is good. Therefore, in the present invention, the density correction amount and color correction amount are determined using the density average value of the designated main image, and the basic exposure amount determined by the exposure amount calculation formula (11) is corrected.

FIG. 8 shows a photographic printing apparatus for carrying out this method, in which the same members as in FIG. 1 are given the same reference numerals.

In FIG. 8, there is a half mirror 66 behind the lens 33.
is arranged, the light that passes through this enters the sensor unit 35, and the reflected light enters the color TV camera 66. This color TV camera 66 captures a color negative image and outputs a video signal. This video signal is converted into a positive image video signal by a negative/positive converter 67 and then sent to a controller 68. The controller 68 displays a positive image 70 on the display surface of the color monitor 69 and sends position information created from the synchronization signal to the position detection section 71. This positive image 70 is observed, and the boundary of the portion determined to be the main image is indicated using a position specifying means, for example, a light pen 72. This light pen 72, when a specified point lights up on the color monitor 69,
This is photoelectrically converted and sent to the position detection section 71. This position detection section 71 sends the coordinate position on the color monitor 69 to the microcomputer 43 when a signal from the light pen 72 is generated.

In addition to the light pen 53, a touch panel sensor, joy snack, digitizer, trunk ball, XY cursor, etc. can be used as the position specifying means.

In addition, a spot illumination section or a liquid crystal panel is arranged under the negative carrier 12, and the image sensor unit 3 can be used to illuminate or dim a part of the main image, and to illuminate or dim it.
5, and by comparing these two photometric values pixel by pixel within the microcomputer 43, the coordinate positions of portions with different illumination conditions may be detected. -Furthermore, it is also possible to check the base density, measure the density with spot illumination on a part of the main image, and detect pixels whose density is lower than the base density. Furthermore, when one point is designated, it is convenient to automatically detect portions that are the same or similar in color to this point and determine these as the main image area.

Next, with reference to FIG. 9, a method of correcting the basic exposure amount using the average density value of the main image will be described. first,
The scanner unit 35 scans the color image,
The density of each pixel is measured and loaded into the RAM 45.

Next, when the lantern pen 72 is operated to indicate the boundary of the main image, the microcomputer 43 detects the position detection section 71.
An image area table is created using the position information from , and data indicating whether it is the main image area is written. FIG. 10 shows the image area. Reference numeral 74 indicates a first image area, reference numeral 75 indicates a second image area, and reference numeral 76 indicates a main image.

Next, the density average values (DR, DO, D
), and calculate the average density value (CR, C
c, Cs). Further, the average density value (PR, PG, P,) is calculated from each pixel forming the main image. Using these density average values, the density control amount ED1.
1 and color control NEC1 are calculated.

Concentration control amount calculation formula (% formula %) The function F (D) is for controlling the concentration as described above, and the function F' (P) is for correcting the concentration. For example, it is expressed by the following formula. be done.

F' (P) = kt (a'PH+b'
Ps"C' Pg )/ (a' +bl
+c') Here, each symbol is as follows.

kJ: Constant n: Integer less than 50 ■J: Other image feature amount, for example, maximum density value.

Minimum density value, full screen or part of the screen Average concentration value etc. Color control amount calculation formula %formula%) A specific example of this formula (4) is as follows.

EC contribution = to (C1l −D”) + 2 (
p*-pR') ECc ""kt (Cc
D')+kz (Pa Pc'
) ECB = kl (CHD' ) + kz (P
a Pi') where P, ", PG", PB
As ', p*'=PR+P-PPG'=pc+p-pPs=P+++pP are used. However, P and P are as follows.

P= (a"PR+b' Pa +C' Pg
)/ (a'+b'+(')P'=(a' PR+ b' Pc, +c' lower a)
/(a'+b"+c') P++, , Pa, Pg are the densities of the main image that serve as predetermined standards. In addition, the function f'(P
), P, -P, etc. can be used.

The coefficients ,kt may be constant values, but can be determined as follows.

When the number of pixels in the main image is O to 1, + = 1.0 k, = Q, 0 When the number of pixels in the main image is 2 to 50, + = 0.6 kz = O14 When the number of pixels in the main image is 6 to 10 Sometimes 1+0. 4 kz = '0.6 When the number of pixels of the main image is 11 or more + = 0.2 kz =0.8 Exposure control amount E
8 can be obtained from an exposure control amount calculation formula using the density control amount E D w and the color control iEc.

Exposure calculation formula % formula % (5) Substituting the density control formula (3) and color control formula (4) into this exposure calculation formula (5), E; = CF (D) + r, (C)] +
CF” (P)+l, (P)] ・ ・(C6
In this exposure amount calculation formula (6), the first term is the basic exposure amount common to all frames, and the second term is determined by the operator's designation, so it becomes the exposure correction amount.

Therefore, the exposure amount calculation formula (6) can be said to be an equation for correcting the basic exposure amount calculated using the density average value using the image feature amount extracted from the main image.

In actual exposure control, the following equation is used.

E”,=1.+11”×Ei...(7) Here,
Ei and x% are as follows.

18: Correction amount 1,゛ to achieve the desired color density
: Correction amount for correcting the color density of a printed photograph that changes depending on the density of the color original image In the above embodiment, the density average value (CR, Cc, Ca) is calculated from the image area 76 shown in FIG. The density average value (C, I
, Co , Cm ) may be calculated.

This improves the accuracy of the background color and is effective when the background image is small. In addition, the exposure amount calculation formula (6)
uses the same functional formula, but a different functional formula may be used depending on the type and size of the main image and the type of scene.

Further, although a scanner unit and a color TV camera are used, they may also be used in combination. For example, color T
The density value of each pixel may be determined from the video signal from the V camera.

Although the above embodiment is a photographic printer, the present invention can also be used in a negative verification machine. Furthermore, although the photochromic filter device is used to control the printing exposure amount for each color, instead of this, cyan, magenta, and yellow cant filters may be used to adjust the exposure time for each color.

Moreover, it is red.

Additive printing may be performed using green and blue filters. In this case, either simultaneous printing using three light sources or sequential printing using one light source and sequentially inserting each color filter into the printing optical path may be used.

〔Effect of the invention〕

In the photographic printing exposure control method of the present invention, an average density value for performing density control and an average density value for color control are obtained from different image areas, and a function using these average density values as variables is calculated. Since the exposure amount is controlled using a formula, it is possible to achieve good density even in backlit scenes and scenes where the main image is on the shadow side, which would have been a problem if the average density value of the entire screen was used. . Furthermore, since the average density of the peripheral area of the screen is used, it is possible to obtain printed photographs with good color balance.

Furthermore, since pixels with a specific color are extracted from the center of the screen and the average density value of these pixels is used to control the exposure amount, the influence of the light source color can be removed.

Furthermore, since the specified average density value of the main image is used, the finish of the main image can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a photographic printing apparatus embodying the present invention. FIG. 2 is an explanatory diagram showing an example of an image sensor. FIG. 3 is a flowchart showing the procedure of exposure control according to the present invention. FIG. 4 is an explanatory diagram showing the image area. FIG. 5 is an explanatory diagram showing another image area. FIG. 6 is a flowchart showing the procedure of exposure control in which the influence of the light source color is removed. FIG. 7 is a graph showing specific color areas. FIG. 8 is a schematic diagram showing an embodiment of a photographic printing apparatus provided with main image designating means. FIG. 9 is a flowchart showing the procedure of exposure control using the average density value of the main image. FIG. 10 is an explanatory diagram showing the image area. 10-.White light source 13..Color negative film 16..Cyan filter 17..Magenta filter 18..Yellow filter 26..Color photographic paper 35..Sensor unit 56..First image area 57..Second image area 59.60...First image area 59.61...Second image area 66...Color TV camera 69...Color monitor 70...Positive image 72...Light Ben 74...First image area 75...Main image 76...Second image area. (G-B) Figure 1○ Procedural Amendment

Claims (13)

[Claims] (1) In a photographic printing exposure control method for controlling the exposure amount for printing a color original image onto color photographic paper, each pixel of the color original image is photometered by three-color separation to obtain three-color density values, and a predetermined value is determined. A density average value (D_R, D_G, D_B) is calculated from the three-color density values of each pixel included in one image area, and a density average value (C_R) is calculated from the three-color density values of each pixel included in a predetermined second image area. . C_
B), and the exposure amount E_i (i represents any one of red, green, or blue) is calculated from the exposure amount calculation formula having at least these two functional equations as addition terms. A photographic printing exposure control method. (2) The first image area is the entire peripheral area of the color original image or an area excluding specific pixels from the peripheral area, and the second
2. The photographic printing exposure control method according to claim 1, wherein the image area is an area excluding the center of the color original image. (3) The first image area includes pixels from the periphery of the color original image excluding pixels whose density is equal to or higher than a predetermined value or pixels with low contrast between adjacent pixels, and all pixels in the center of the color original image. A photographic printing exposure amount control method according to claim 2, characterized in that the method comprises: (4) the first image area is the center of the color original image;
3. The photographic printing exposure amount control method according to claim 2, wherein the second image area is a peripheral area of the color original image. (5) In a photographic printing exposure control method for controlling the exposure amount for printing a color original image onto color photographic paper, each pixel of the color original image is photometered by three-color separation to obtain three-color density values, and a predetermined value is determined. The density average value (D_R, D_G, D_B) is calculated from the three-color density values of each pixel included in one image area, and the density average value (L_R) is calculated from the pixels included in a specific color area.
. Functional formula F(D_R
, D_G, D_B) and a functional formula f_ for controlling the color.
i (C_R, C_G, C_B) and a functional expression g_i (L_R, L_G, L_B) for color correction, and then calculate the exposure amount from an exposure amount calculation expression that has at least these three functional expressions as addition terms. A photographic printing exposure amount control method characterized by calculating E_i (i represents any one of red, green, or blue). (6) The first image area is the entire peripheral area of the color original image or an area excluding specific pixels from the peripheral area, and the second
6. The photographic printing exposure amount control method according to claim 5, wherein the image area is an area excluding the center of the color original image. (7) The first image area includes pixels from the periphery of the color original image excluding pixels whose density is higher than a predetermined value or pixels with low contrast between adjacent pixels, and all pixels in the center of the color original image. A photographic printing exposure amount control method according to claim 6, characterized in that the method comprises: (8) the first image area is the center of the color original image;
7. The photographic printing exposure control method according to claim 6, wherein the second image area is a peripheral area of the color original image. (9) In a photographic printing exposure control method for controlling the exposure amount for printing a color original image recorded on a color original image onto color photographic paper, each pixel of the color original image is photometered by three-color separation to obtain three-color density values. The density average value (D_R, D_G, D_B) is determined from the three-color density values of each pixel included in the predetermined first image area.
The density average value (C_R, C_G, C_B
), and also calculate the density average value (
P_R, P_G, P_B), and from these respective density average values, a functional formula F(D_R, D_
G, D_B) and f'(C_R, C
_G, C_B)' and the functional formula F' for correcting the density.
(P_R, P_G, P_B) and a functional formula f'(P_R, P_G, P_B) for correcting the color, and use an exposure amount calculation formula that has at least these four functional formulas as addition terms. A photographic printing exposure amount control method characterized by calculating an amount E_i (i represents any one of red, green, and blue). (10) The first image area is the entire peripheral area of the color original image or an area excluding specific pixels from the peripheral area, and the second image area is an area excluding the center of the color original image. A photographic printing exposure amount control method according to claim 9. (11) The first image area includes pixels from the periphery of the color original image excluding pixels whose density is higher than a predetermined value or pixels with low contrast between adjacent pixels, and all pixels in the center of the color original image. A photographic printing exposure amount control method according to claim 10, characterized in that the method comprises: (12) The photographic printing exposure control method according to claim 10, wherein the first image area is a central portion of the color original image, and the second image area is a peripheral portion of the color original image. (13) The photographic printing exposure control method according to claim 9, wherein the first image area is the center of the color original, and the second image area is the entire color original.