JPH01112232A - Color enlarger - Google Patents

Abstract

PURPOSE:To select a combination of color filters which facilitate color correction according to a photographic film type and the color balance of printing frame by providing a mode assigning means which assigns the combination of the color filters which is used for the color correction, and calculating the filter value of the assigned color filters. CONSTITUTION:The title enlarger is provided with a mode assigning means 80 which assigns the combination of two color filters to be used for color correction among three color filters 43-45, a means 77 to measure the density values of three colors of the printing frame, an arithmetic means which calculates to color filter value of the two color filters selected by said density values of three colors and exposure time, and a display device 37 which displays the calculated color filter value and the exposure time. Thus the combination of the color filters which are appropriate for color correction is assigned by operating the mode assigning means 80, and with the assigned color filters, the arithmetic part calculates and displays the color filter value for the good color balance and the exposure time for the correct density.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in color enlargers.

[Conventional technology]

The original color image recorded on color photographic film (color negative film, color reversal film, etc.) is enlarged and projected onto color photosensitive paper (color photographic paper or color reversal photographic paper, etc.) using a color enlarger, and a color positive image is created on this color photosensitive paper. It is burned as. During this photo printing, if the original color image (hereinafter referred to as a print frame) is enlarged and printed directly onto color photosensitive paper, the characteristics of the color photo film and color photosensitive paper, the spectral intensity of the printing light source,
Due to the influence of the color balance of the print frame, the color balance of the photo-printed image deteriorates, making it impossible to finish the image in colors that are faithful to the subject. Therefore, in subtractive color printing, three color correction filters (hereinafter simply referred to as color filters), a cyan filter, a magenta filter, and a yellow filter, or two of these color filters are used to transmit the print frame. red light.

Color correction is performed by adjusting the ratio of green light and blue light to achieve a good color balance. Further, some of the print frames include overexposed and underexposed frames, and it is necessary to adjust the exposure time for these frames to achieve appropriate density.

Conventional color enlargers use a color analyzer to calculate the color filter values and exposure times of print frames. This color analyzer consists of a sensor that measures the transmitted light of a print frame by separating it into three colors, a calculation unit that calculates color filter values and exposure time, and a display unit that displays the calculated color filter values and exposure time. has been done.

[Problem that the invention seeks to solve]

Generally, when printing a color negative film, color correction is performed using a magenta filter and a yellow filter, and when printing a color reversal film, a combination of a cyan filter and a magenta filter, or a combination of a cyan filter and a magenta filter is used. Color correction is performed using a combination of a cyan filter and a yellow filter.

By the way, since color enlargers mainly print color negative films, conventional color analyzers calculate and display magenta filter values and yellow filter values as color filter values. Therefore, there is a problem in that it is difficult to perform color correction on color reversal films and the like.

[Object of the Invention] The object of the present invention is to provide a color enlarger that is capable of calculating color filter values of two specified color filters among three color filters. be.

[Means for solving problems]

In order to achieve the above object, the present invention provides a mode specifying means for specifying a combination of two of the three color filters used for color correction, and a means for measuring the three color density values of a print frame. , which is provided with calculation means for calculating the color filter values and exposure times of the two color filters selected from the three color density values, and a display device for displaying the calculated color filter values and exposure times. It is.

[Effect]

Depending on the type of photographic film and the color balance of print frames, a combination of color filters suitable for color correction is specified by operating the mode specifying means. The calculation unit calculates and displays a color filter value for achieving a good color balance and an exposure time for achieving an appropriate density when a designated color filter is used. Printing is performed after setting the filter adjustment knob to the calculated color filter value.

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

〔Example〕

The color enlarger shown in FIG. 2 is used in a darkroom, and a color photosensitive paper 11 is set at a predetermined position on a plywood board 10 via an easel mask (not shown). Further, a support post 13 is fixed to the rear side of the base plate 10 via a support stand 12, and a main body 14 is attached to this support so as to be movable up and down. This main body 14 is the lamp house 1
5. Diffusion section 16. Bellows 17. Lens board 18. It is composed of a sliding tube portion 19.

A lamp, a magenta filter, a yellow filter, and a cyan filter are housed in the lamp house 15, and the magenta filter value, yellow filter value, and cyan filter value can be adjusted by operating the filter adjustment knobs 22 to 24. Can be done. The outer peripheries of these filter adjustment knobs 22 to 24 are provided with scales representing color filter values. In addition, the filter open lever 25 is
This is for retracting all the color filters from the optical path and setting the color filter values to "zero".

A negative carrier 28 is provided at the bottom of the diffusion section 16 and can be taken out and put in, and a color photographic film is set in this. An enlarger lens 29 is mounted on the lens board 18.
is attached, and a bellows 17 is attached between this lens board 18 and the diffusion section 16. The sliding cylinder part 19 is fitted into the column 6-13, and the main body 1 is released by the lock release knob 30.
When the lock 4 is released, it can be moved up and down along the support column 13. Further, the sliding cylinder portion 19 is provided with a focus adjustment knob 31, and by turning this, the threaded rod 32 is rotated. Since this threaded rod 32 is screwed into the lens board 18, the enlarger lens 29 moves in conjunction with the operation of the focus adjustment knob 31 to adjust the focus. Note that an enlargement scale 13a is attached to the support 13.

A keyboard 35 is connected to a control box 36 for specifying channels and modes.

Enter print instructions, etc. control box 36
A microcomputer is built inside, and a display 37 for displaying color filter values, exposure time, etc. is attached to the front.

FIG. 3 shows the optical system of the color enlarger. The white light emitted from the lamp 40 is passed through two condensing lenses 41.
The light is focused by the mirror 42 and then reflected downward by the mirror 42. The printing light reflected by this mirror 42 is filtered through a magenta filter 43. Yellow filter 44. The light quality is adjusted by passing through the cyan filter 45. These color filters 43-4
5 is inserted into the optical path in conjunction with the operation of the filter adjustment knobs 22-24. In addition, the filter open lever 25
When the color filters 43 to 45 are operated, the color filters 43 to 45 are set to the open position where they are retracted from the optical path, and this state is detected by the sensor 46. Each of these members is housed within the lamp house 15.

The mixing box 48 is composed of a rectangular tube 49 whose inner surface is a mirror surface and a diffusion plate 50, 51 attached to the open end of the rectangular tube 49, and sufficiently diffuses the light transmitted through the color filters 43 to 45. This mixing box 48 is housed within the diffusion section 16.

The printing light transmitted through the mixing box 48 illuminates the color photographic film 52 set on the negative carrier 28. During photometry, the printing light transmitted through the color photographic film 52 is sent to the red sensor 53, the green sensor 54, and so on. The light is measured by a blue sensor 55 (not shown). During photo printing, color photosensitive paper 11 is placed on plywood 10, and print frames of color photographic film 52 are enlarged and projected onto color photosensitive paper 11 by an enlarging lens 29.

FIG. 4 shows the filter adjustment mechanism.

A color filter, for example, a magenta filter 43, is held in a U-shaped filter holder 60.

This filter holder 60 has one protruding piece 60a.
is in contact with the logarithmic cam 61, and the other protruding piece 60b is in contact with the bent piece 62a of the bell crank lever 62.

The logarithmic cam 61 has a cam surface formed in a logarithmic curve, and rotates about the shaft 63 when the filter adjustment knob 22 is turned, thereby causing the projecting piece 6 of the filter holder 60 to rotate.
Press 0a. The filter holder 60 rotates counterclockwise around the bell crank lever 62, and moves the magenta filter 43 in and out of the optical path 64 to convert color filter values.

An L-shaped groove 66 is formed in the filter open lever 25, into which fixing pins 67 and 68 are respectively fitted. When the filter open lever 25 is moved to the open position, the fixing pin 68 enters the engaging portion 66a of the groove 66 due to the biasing force of the spring 69, so that the filter open lever 25 is locked in the open position. This locked state is detected by a sensor 46 using a photosensor or a microswitch. When the filter open lever 25 is pushed in against the spring 69, the fixing pin 68 is pulled out from the engaging portion 66a, so that the filter open lever 25 is returned to the illustrated reset position by the stored force of the spring 69.

When the filter open lever 25 moves to the open position, the arm 25a pushes the bell crank lever 62. Since the bell crank lever 62 rotates counterclockwise about the shaft 70, the bent piece 62a pushes the protruding piece 60b of the filter holder 60, forcibly extracts the magenta filter 43 from the optical path 64, and removes the color filter. Set the value to zero. This bent piece 62a is bent downward (1'), and at the same time, the yellow filter 44 and the cyan filter 45 are also retracted from the optical path 64. Code 71.72
is a spring for urging the filter holder 60. Note that the yellow filter 44 and the cyan filter 45
Since the filter adjustment mechanism has the same configuration, its explanation will be omitted.

FIG. 5 shows the electrical configuration of the color enlarger.

Red sensor 53. The green sensor 54 and the blue sensor 55 photoelectrically convert the light transmitted through the color photographic film 52 and send the output signals to the amplifier 75. The signals amplified by the amplifiers 75 are sent to an A/D converter 76.
After being converted into digital data, it is taken into the CPU 77.

The CPU 77 calculates an approximate density value (hereinafter simply referred to as a density value) by logarithmically converting the reciprocal of the captured measurement value, and writes this density value into the memory 78 .

The memory 78 is composed of a ROM and a RAM, as is well known, and stores a total control program and a plurality of channels depending on the type of color photographic film. Each channel includes the three-color density values (R, GN, BN) and gray average density value (DN) of the normal standard frame.
), over standard frame three color density values (Ro, Go,
Bo), gray average density value (Do), three-color density value (Ro, Gu, Bu) of under standard frame, and gray average density value (DO). ), the standard filter value (
Contains fixed data such as MN, YN, CM), coefficients of arithmetic expressions, etc. Note that in this example, a specific color photosensitive paper is used, but if multiple types of color photosensitive paper are used, the color photographic film and color photosensitive paper may be combined, and the It is desirable to have a channel available for this purpose.

The keyboard 35 includes mode designation keys 80. Channel designation key 81. Density key 82. Numeric keypad 83 for changing exposure time coefficients, correction coefficients, etc. Calibration switch 84. A print start key 85 is provided. - For boat fishing, color negative films use a combination of magenta and cyan filters for color correction, and color reversal films use a combination of cyan and magenta filters or cyan and yellow filters. .

Therefore, a mode designation key 80 is provided so that two color filters can be selected from the three color filters depending on the type of color photographic film. This mode designation key 80 is, for example, No. 1
When the key is operated, a combination of a magenta filter and a cyan filter is selected, and a magenta filter value and a cyan filter value for improving the color balance are calculated. Also, when the No. and 2 keys are operated, the filter values of the cyan filter and magenta filter are calculated, and the No. 2 key is operated.

When key 3 is operated, the cyan filter value and the yellow filter value are calculated. Further, when the mode designation key 80 is operated, the mode display lamps 88a to 8 of the display 37
One of the color filters 8c lights up to display the type of the selected color filter.

=13- =12- The channel designation key 81 is used to designate a channel corresponding to the type of color photographic film to be printed from among a plurality of channels prepared according to the type of color photographic film. , the channel is specified by operating the key corresponding to this channel number.

The density key 82 is used to correct density feria by increasing or decreasing the print density, and is composed of a plurality of keys with different density steps. When the density key 32 is operated according to the content of the print frame, the exposure time is corrected and the corrected exposure time is displayed on the display 37.

The calibration switch 84 is used to start calibration, and the print start key 85 is used to start photo printing.

The display 37 includes a channel display section 89 using a 7-segment display unit. It includes an exposure time display section 90° filter value display sections 91 and 92.

The timer 95 turns on the lamp 40 via the driver 96 for the exposure time calculated by the CPU 77, and prints the print frame onto the color photosensitive paper 11 during that time.

Next, calibration will be explained with reference to FIGS. 6 and 7. If the photographic film to be printed is a color negative film, the channel is designated by operating the channel designation key 81 on the keyboard 35 depending on the type of photographic film. Next, a negative of the color negative film to be printed (the unexposed portion of the color negative film has been developed) is set in a negative carrier 28, and this negative carrier 28 is inserted into the diffusion section 16.

For blank removal, after setting the negative, turn on the calibration switch 84, and then set the filter open lever 25 to the open position. When the filter open lever 25 is set to the open position, the magenta filter 43. Yellow filter 44. cyan filter 45
is withdrawn from the optical path 64, and the color filter value becomes zero. At the same time, the filter open lever 25 is moved to the sensor 46.
This detection signal is sent to the CPU 77.

The CPU 77 sends a signal to the driver 96 to turn on the lamp 40.
lights up. The printing light emitted from the lamp 40 is transmitted through the condensing lens 41. Mirror 42° mixing box 4
After passing through 8, the base plate reaches the negative and illuminates it. In this case, the transmitted light of the negative is detected by the red sensor 53. The light enters a green sensor 54 and a blue sensor 55, and these sensors perform average photometry for each color. Each sensor 5
The output signals 3 to 55 are amplified by an amplifier 75, and then
The signal is input to an A/D converter 76. This A/D converter 76
After the light emission of the lamp 40 has stabilized, the analog signal is converted into a digital signal and sent to the CPU 77 as a measured value. The CPU 77 calculates an approximate concentration (direct value) by logarithmically converting the reciprocal of the measured value.

The density value obtained by photometrically separating the negative into three colors is the base density value of the negative film, and is added to the fixed data read out after specifying the channel to calculate the standard negative density value. That is, as shown in FIG. 7, the density values obtained by subtracting the base density value from the standard negative density value D1= , D2+ , D
3t (i is red.

(representing either green or blue) is stored as fixed data in each channel, so if the characteristic curve is shown by a solid line, the fixed data is added to the measured base density value b1. As a result, the normal standard negative density value DNI□, the over standard negative density value DO1i, and the under standard negative density value DUl are obtained. Also,
In addition to the three-color density values of red density value, green density value, and blue density value, the standard negative density value also includes a gray average density value. It can be found by taking the arithmetic mean of In FIG. 7, "rN" represents a normal standard negative, "0" represents an overstandard negative, and "rU" represents an understandard negative. Further, since the standard negative density value differs depending on the type of negative, different fixed data is stored for each channel.

If there is a change in the light intensity or quality of the lamp, or a fluctuation or change in the signal processing system such as an amplifier, the characteristic curve will shift as shown by the dashed line. In this case, the base density value will be b2, so for example, normal The standard negative density value is DN2i (DN
2i=b2 +D1i'').In this way, for each channel, the density value obtained by subtracting the base density value from the standard negative density value is written in the memory 78 as fixed data, so the lamp, amplifier, density value measurement The standard negative density value is determined by taking into account the effects of aging and fluctuations in the CP sensor, etc., and as a result, these effects are corrected and correct exposure control is performed.
The lamp 40 is turned off by U7.7.

After the calibration is completed, the frames to be printed on the color negative film (hereinafter referred to as print negatives) are photographically printed according to the procedure shown in FIG. First, the user operates the mode designation key 80 on the keyboard 35 to designate a combination of two color filters for which color filter values are to be calculated. In the case of color negative film, it is better to use a magenta filter and a yellow filter, so No.
Press the 1 key. When this key N051 is operated,
The lamp 88a of the display 37 lights up. Depending on the print negative scene, a combination of a cyan filter and a magenta filter or a combination of a cyan filter and a yellow filter may be appropriate. In such cases, operate the No, 2 or N013 key. do. When these keys are operated, a lamp 88b or 88c corresponding to the selected key type lights up.

After specifying the mode, a color negative film is set on a negative carrier 28 shown in FIG. 2 and pushed into the diffusion section 16. Next, operate the lock release knob 30, and then
3, move the main body 14 up and down along the magnification scale 1.
3a, the main body 14 is stopped at a desired magnification position. After adjusting the printing magnification, the user operates the numeric keypad 83 of the keyboard 35 to input the scale read from the enlargement magnification scale 13a.

As shown in FIG. 4, when the filter open lever 25 is operated, the magenta filter 43. Yellow filter 44.
The cyan filter 45 is completely retracted from the optical path 64. When the color filters 43 to 45 are opened, the lamp 40 is turned on as described above, the three color density values of the print negative are measured according to the procedure described above, and the gray average density value is also calculated from the arithmetic mean of the three color density values. Calculated.

The CPU 77 uses the three-color density values and the gray average density value of the print negative to calculate the correction filter value and the standard filter value 9.
Calculate color filter values. The calculated magenta and yellow color filter values are displayed on filter value display sections 91 and 92 of the display 37, respectively. Also, CPU7
7 calculates the exposure time and displays it on the exposure time display section 90 of the display 37. Here, it is necessary to perform density correction for print negatives in which there is a possibility that density fetch may occur. When performing this density correction, by operating the density key 82 of the keyboard 35 and inputting a density key value, the exposure time corrected by the density key value is displayed.

Read the filter value on the filter value display section 91.92 of the display 37, and adjust the filter adjustment knob 22.23 so that this value matches the scale of the filter adjustment knob 22.23.
operate. For example, when the filter adjustment knob 22 is operated, the logarithmic cam 61 rotates, so the filter holder 6
The position of the protruding piece 60a of 0 changes. After or before operating the filter adjustment knobs 22, 23, if the filter open lever 25 is pushed and returned to the reset position, the filter holder 60 will move to the right in FIG.
The magenta filter 43 and the yellow filter 44 enter the optical path 64 and stop at positions regulated by the logarithmic cam. When the filter open lever 25 is released, the CPU 77 turns off the lamp 40. Note that with the filter open lever 25 set in the open position, the focus adjustment knob 31 is operated to adjust the focus of the enlarger lens 29. When the focus adjustment knob 31 is operated, the lens board 18 moves up and down in the optical axis direction.

Color photographic paper is used as the color photosensitive paper 11, and after setting it on the base plate 10, the print start key 85 of the keyboard 35 is turned on. The CPU 77 uses the timer 9
The lamp 40 is turned on for the exposure time calculated by controlling 5, and the print negative is printed on the color photographic paper. If the same color negative film is to be printed multiple times, the print start key 85 may be operated after replacing the color photographic paper. Furthermore, when printing another color negative film of the same negative type, it is sufficient to replace it with another color negative film and then repeat the above-mentioned procedure. Note that when printing different types of negatives, it is necessary to select the appropriate channel by operating the channel switching key.

If the color photographic film to be printed is a color reversal film, bluish-white printing light is just right, so it is best to perform color correction using a cyan filter. In this case, the mode designation key 80 No, 2 key or No,
Since the 3 key is selected, the lamp 88b or 88c is lit, and the cyan filter value and the magenta filter value, or the cyan filter value and the yellow filter value are displayed on the display 37. In the case of a color reversal film, color reversal photographic paper is used as the color photosensitive paper 11.

Next, using color negative film as an example, we will explain the calculation of color filter values to achieve appropriate color balance in Section 8.
This will be explained with reference to Figures 10 to 10. The gradation characteristic of color negative film is R (red).

G (green) and B (blue) are different, and the sensitivity characteristics of the photometric sensors 53 to 55 are also different, so as shown in FIG. 8, the characteristic curves of R2O and B are not parallel. Therefore, the color balance of the over standard negative and the under standard negative will be different from the color balance of the normal standard negative. FIG. 8 also shows the three-color density values of normal standard negative N, over standard negative 0, and under standard negative U. These three color density values are actually calculated by the method shown in FIG. The relationship between the three color density values and the symbols is as follows.

RN: Red density value of normal standard negative GN: Green density value of normal standard negative B8 2 Blue density value Ro of normal standard negative = Red density value Go 2 of over standard negative Green density value Bo 2 of over standard negative
Blue density value R of the over standard negative: Red density value GLI of the under standard negative 2 Green density value BU of the under standard negative BU: Blue density value of the under standard negative Color enlargers use two types of color filters to To perform the correction, the difference between the two color density values is used as a color balance value. In this case, a magenta filter and
Since the yellow filter is selected, the color balance values are expressed as (R-G) and (R-B). If we take this color balance value in the horizontal direction and the gray average density value in the vertical direction and display the color balance values for the normal standard negative, over standard negative, and under standard negative shown in Figure 8, we get the color balance values shown in Figure 9. Become.

The color correction amount is the color balance value of the normal standard negative ((
RN-GN), (RN-BN)), and is determined according to the deviation of the color balance value of the print negative with respect to this, so in FIG. 9, the color balance value of the normal standard negative is taken as the Z axis. That is, the color balance point P of the normal standard negative is placed on the Z axis where the color balance value is (0°0). Therefore, the color balance point P of the over standard negative and the color balance point Pu of the under standard negative are expressed by the following equation.

po=((Ro-co)-(RN-GM)).

(Ro Bo) (RN BN)) Pu-
[(RU-GU)-(RN-GN).

(Ra BLI) (RN BN)) Color balance points P9 and P. The straight line ZI connecting these represents the shift of the standard color balance value on the overexposed side,
Since the Z-axis direction represents the gray average density value, the shift amount of the standard color balance value is proportional to the gray average density value. Similarly, a straight line Z2 connecting color balance point P8 and Pa represents a shift of the standard color balance value on the underexposure side.

Here, R: Red density value of the print negative G: Green density value of the print negative B: Blue density value of the print negative D: Average gray density value of the print negative (R+G+B/
3) DN = gray average density value of normal standard negative (RN+
GN+B N/3) Do2 Gray average density value of over standard negative (RO+Go+Bo/3) DU = Gray average density value of under standard negative (Ru
+ Go + Bu / 3), the color balance point P of the print negative is as follows.

P=((RG)-(RN-CyN).

(R-B)-(R,-BN)) This color balance point P exists on the horizontal plane "2" where the average gray density value is D on the Z axis. This horizontal plane is
When D>DN, it exists on the overexposed side, as shown in FIG. 9, and when D<DN, it exists on the underexposed side.

Let PZ be the point on the Z axis where the gray average density value is equal to
The point where the plane including this point PZ intersects the straight line Z1 is PZ,
Then, in conventional color correction, the length of the color balance point P and point PZ of the print negative is the difference in color balance value, and the length of the point P2 and point PZ obtained by multiplying this by the correction coefficient Kc is This is the amount of color correction. On the other hand, in the embodiment of the present invention, the color balance point P and the point PZI
The length of is the deviation of the color balance value, and the correction coefficient K is added to this. The length of point P1 and point PZ1, which are multiplied by , becomes the color correction amount.

For example, the color balance point P on the over side. (-0,
02G, -0,04B) and D-(D.-DN)/2
Then, the standard color balance point PZ is (-0,0I
G, -0,02B).

Here, the color balance point P of the print negative is (-0,
05G, -0,02B), the deviation from the standard color balance point PZ is (-0.

04G, O, 0OB), so if the correction coefficient is set to 0.8, the color correction amount is "-0.

It becomes 032Gj. Since the filter value is the density value multiplied by 100, the corrected filter value is -3.2GJ, which is r3.2 of the magenta filter's filter value.
Corresponds to J.

On the other hand, in the conventional method, the color balance of the normal standard negative is used as the standard color balance, so the color balance value of the print negative (-0,05G, -0,02B)
Color correction will be performed on. Therefore, if the correction coefficient Kc is the same, the color correction amount is (-0
, 04G, -0,016B), which has a magenta filter value of "4" and a yellow filter value of rl, 6J. In this conventional method, the color correction amount tends to be excessive or decreased, but in the embodiment of the present invention, for the print negative on the opaque side, the color balance value of the point existing on the straight line Z1, that is, The value obtained by proportionally distributing the color balance value of the over standard negative with the gray average density value of the print negative is used as the standard color balance value, and for the under side print negative, the color balance value of the point existing on the straight line Z2 is the standard color balance. Since it is used as a value, the amount of color correction becomes appropriate.

Next, an example of an arithmetic expression for color filter values based on the above method will be described. From the magnitude relationship between the average gray density value of the print negative and the average gray density value D of the normal standard negative,
Determine whether the print negative is over or under.

D>DN...Over side D<DN...Underside When it is determined that the print negative is on the overside, the standard color balance value (point pz on straight line Z1, ) is obtained from the following equation.

(a) For green color, (RN-GN) + (D-DN)
O-co)-(RN-CAM))/(Do
-DN) -・(1)(b) For blue color, (RN BN)+(D DN)X[(Ro Bo
)-(RN-BN))/(Do-DN)--(
2) The deviation (cc, co) of the color balance value of the print negative from this standard color balance value can be found from the following equation.

(a) For green color, Cc −(RG) −(RN −C,,) + (D
-D, )X((R, -Go)-(R, -GN))/(
Do-D, 4)...(3) (b) For blue color, CB-(RB) (RN BN )+'(D
DN ) x [(RO-BO) −(RN −Bll
))/(Do DN) (4) The correction filter values FCG and PCB can be found from the following equations.

FCG = Kc XCG X 100... (5) FCB
=KoxCB×100... (6) When this correction coefficient Kc is made smaller than "1", the photometry sensor 53
A value of ~55 results in a lower correction that slightly corrects the photometric color balance, and a value greater than "1" results in a high correction that emphasizes the correction.

Standard filter values for properly printing normal standard negative N, over standard negative O, and under standard negative U (
FS,, FS,) can also be calculated in the same way as the standard color balance described above.

F SM = MN + (D DN ) X (Mo-M
N)/(Do-DN)...(7)FSy=YN+
(D-DN) Magenta filter value Mo = Magenta filter value for properly printing an over standard negative YN: Yellow filter value for properly printing a normal standard negative Yo Yellow filter value for properly printing an over standard negative These filter values are determined at the time of device design and are written into memory 78 as fixed data.

Therefore, the color filter values (FM, FV) for optimizing the color balance of a printed photograph can be obtained from the following equation.

F M = F S M 10F CG... (9) Fv
=FSy +FCB...GO) +Figure 10 shows the correction filter value and standard filter value.

This is a schematic representation of color filter values. Here, F
Cl (i represents green and blue) is a correction filter value, and FS= (j represents magenta and yellow) is a standard filter value.

If the print negative is on the under side, the under standard negative is used, so the calculation formulas (3) and (4) are used.

(7) and (8) are transformed as follows.

CG-(R-c)-(RN-ON)+CD
-DH)x ((RU -Go) -(R, -GN
) )/(Du −DN ) −・(o) CB=(RB) (RN BN)+(D D
N) x ((RLI -BLI) -(RN -BN
))/(DIl-DN) ・ ・02)F
SM = MN + (DD, +) x (M
u MN ) / (DODN) ・ ・03
)FSy = YN + (D-DH) x (Yu-
YN ) / (DU -DN) -- MU: Magenta filter value for properly printing under standard negatives Yu: Yellow filter value for properly printing under standard negatives Color photographic film to be printed In the case of a color reversal film, a combination of cyan and magenta, or a combination of cyan and yellow is usually used as the color filter. Furthermore, even if the film is a color negative film, if cyan is a little excessive, a combination including a cyan filter is used. In this case, mode designation key 8
0 No, 2 or No, 3 is operated. For example, N
When the o and 2 keys are operated, the calculation formula (3),
(4), (7), (8), (9).

0ω is the calculation formula 0 that changes the reference color from red to blue.
51-+20 is used.

CR-(B-R)-(BN-RN)+(D-D
N)X((B,-RO)-(BN-Rs))/(D
o -DN) ...(+5) CG-(B C) (BN-GN)+ (D
DN)X ((B, -G,)-(BN-GN))/
(Do DN) ・・QO F Sc =CH+ (D DN ) XCCo −
CN) / (Do-DN)...QT)FS
M = MN + (D-DN) X (MO-MN)
/ (D, -DN) ・・0a) FC=FSC
+ (KcXFCRXl 00) ・・Q9) FM
=FSM 10 (Kc XFCG X 100)...QO
Further, when the No. 3 key of the mode designation key 80 is operated, an arithmetic expression based on green color is used.

=34- After calculating the color filter value, the CPU 77 calculates the exposure time T and displays it on the display 37, and the following equation is used for this calculation.

Here, each symbol is as follows.

KI: Exposure time coefficient (exposure time to print normal standard negative to proper density value) K2: 3 to printing magnification value Nislope coefficient (coefficient differs for overexposure and underexposure) DX: Change in density key per step Ratio: 4: The number of stages of the density key: 3. KC and constant DK are stored in the memory 78 as channel data, and are taken into the CPU 77 during calculation. However, the coefficients +, Ks, and Ko can be changed by determining the tendency of printing actually performed and operating the numeric keypad 83 of the keyboard 35. For example, if the overall print density is high, the exposure time coefficient
All you have to do is make it smaller.

In the above example, three types of standard density values are used: normal standard frame, under standard frame, and over standard frame. However, even if four types of standard density values including super over standard frame are used, good.

In addition, in this example, since color correction is performed using two color filters, the color balance value is the density difference between the two colors,
For example, the color filter value is calculated using (R-G), (R-B), but instead of this, (D-G), (
D-B) may be used to calculate the color filter. Furthermore, when using three color filters, (D-R)
, (D-G).

The color filter value can also be calculated using (D-B). In the embodiment of the present invention, the color filters are set manually, but they may be set automatically using a pulse motor or the like.

Furthermore, when the filter open lever 25 is set to the open position, the lamp lights up first, and after the lamp's light emission stabilizes, three-color separation photometry is performed. good.

Furthermore, for reprinting, a manual exposure mode key may be provided on the keyboard, and after operating this key, an exposure time may be input using a numeric keypad, and the photo printing may be performed using the input exposure time.

[Effects of the Invention] As described above in detail, the present invention provides a mode specifying means for specifying a combination of color filters to be used for color correction, and calculates a filter value of the specified color filter. Therefore, it becomes possible to select a combination of color filters that facilitates color correction according to the type of photographic film IN and the color balance of the print frames, and the versatility of the color enlarger can be increased.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the photographic printing procedure of the present invention. FIG. 2 is a perspective view of the color enlarger. FIG. 3 is a schematic diagram showing the optical system of the color enlarger. FIG. 4 is a plan view showing an example of a filter adjustment mechanism. FIG. 5 is a block diagram showing the electrical configuration of the color enlarger. FIG. 6 is a flowchart showing the calibration procedure. FIG. 7 is a graph showing the relationship between the base density value and the standard negative density value. FIG. 8 is a graph showing the three-color density values of standard negatives. FIG. 9 is a three-dimensional graph in which color balance values are plotted in the horizontal direction and gray average density values are plotted in the vertical direction. Figure 10 shows corrected filter values and standard filter values. 3 is a graph showing each color filter value. 11... Color photosensitive paper 14... Main body 22... Magenta filter adjustment knob 23... Yellow filter adjustment knob 24... Cyan filter adjustment knob 25... Filter open lever 29... Enlarger lens 35...Keyboard 43...Magenta filter 44...Yellow filter 45...Cyan filter 46...Filter open detection sensor 53...Red sensor 54...Green sensor 55... - Blue sensor 60...Filter holder 80...Mode designation key. (A) (B) (C)

Claims (2)

[Claims] (1) In a color enlarger in which three color filters are installed in and out of the printing optical path, and color correction is performed by adjusting the amount of insertion of two of these color filters into the printing optical path according to the color filter value. , a mode specifying means for specifying a combination of two color filters to be used for color correction, a means for measuring three color density values of a frame to be printed, and a mode specifying means for specifying a combination of two color filters used for color correction, a means for measuring three color density values of a frame to be printed, and a mode specifying means for specifying a combination of two color filters to be used for color correction; 1. A color enlarger comprising a calculation means for calculating a color filter value and an exposure time, and a display for displaying the calculated color filter value and exposure time. (2) The color enlarger according to claim 1, wherein the plurality of color filters are a cyan filter, a magenta filter, and a yellow filter.