JPS63274824A - Density measuring instrument for photography - Google Patents

Abstract

PURPOSE:To enable density measurement for photography simultaneously with a single photodetecting element by rotating a disk by means of a motor to select an arbitrary filter. CONSTITUTION:A sample is placed on a sample base and the disk 60 is rotated by means of the motor 59 to select the arbitrary filter 65. Light from a lamp 52 for transmission measurement is detected by the photodetecting element 61. A difference between the measured density and the reference density stored in a RAM 87 is then computed. The differences determined with 3 colors; red, green and blue, are respectively multiplied by variable constants, by which color key correction values are calculated. The absolute value thereof is compared and the max. value is selected. This value is multiplied by a density key correction factor, by which a density key correction value is calculated. The color key correction values for the three colors are determined therefrom. The color key correction values for the three colors are respectively multiplied by logarithmic variable constants, by which the exposure time correction factors for the three colors are calculated. The values for the three colors are thereafter displayed by a liquid crystal on a display board 80 and are outputted from an interface 89.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to measuring the density of photographs (color prints, negative films, reversal films, etc.), and to measuring data for exposure time correction (so-called slope correction) of color printing printers. The present invention relates to a photographic density measuring device for obtaining the desired image density, and can also be used to measure the density of color printing.

BACKGROUND ART FIGS. 16 to 19 each show a conventional photographic densitometer.

The concentration measuring device (A) in Fig. 16 has a transmission light receiving chamber (2) on the sample stage (1) side, and an arm (3) installed above the sample stage (1) has a cylinder ( 4) is attached so that it can be slid up and down. Inside the transmission light-receiving chamber (2), the same number of filters (6) as the transmission light-receiving elements (5), three each for red, green, blue, and visual, for a total of 12, are arranged, and the cylinder ( Similarly, 12 reflection light-receiving elements (7) and the same number of filters (8) are disposed within the spacer 4). An irradiation lamp (9) is placed in the center of this cylinder (4), and a scattering plate (10) made of opal glass or the like is fitted in the sampling aperture (2a) on the top surface of the transmission light receiving chamber (2). .

The measurement using this concentration measuring device (A) is performed using the measurement sample (11).
is placed on the sample stand (1), and the cylinder (4) is manually lowered to bring its lower end into close contact with the measurement sample (11). During reflection density measurement, the reflected light reflected from the upper surface of the measurement sample (11) passes through the filter (8) and is received by the reflection light receiving element (7). At a fixed time on the transmission density side, the light transmitted through the measurement sample (11) is diffused by the diffuser plate (10), passes through the filter (6), and is received by the transmission light-receiving element (5).

The concentration measuring device (B) in Fig. 17 is placed on the sample stage (12) side.
A transmission lamp (13) and a diffuser plate (14) are provided,
On the arm (15) side, a disk (17) incorporating a plurality of filters (16) can be manually rotated by a knob (18), and a light guide cylinder (19) can be manually slid up and down. Furthermore, the light receiving element (20) is fixed at a predetermined position.

Measurement with this concentration measuring device (B) is performed using the disk (17).
manually rotate the desired filter (16) to the light receiving element (
20), the measurement sample is placed on the sample stage (12), and the light guide cylinder (19) is lowered. The light from the transmission lamp (13) is diffused by the diffuser plate (14), passes through the measurement sample, passes through the filter (16), and is received by the light receiving element (20). Instrument (B) can only measure transmitted density.

The concentration measuring device (C) in Fig. 18 has an aperture (22a)
to a substrate (22) into which a light scattering plate (21) is fitted.

The arm (23) can move up and down (open and close).

A disk (25) incorporating a plurality of filters (24) is attached to the arm (23) so that it can be manually rotated by a knob (26), and a light receiving element (27) and a light guide cylinder (28) are attached to the arm (23). A reflective lamp (29) is provided, and the light from the reflective lamp (29) is transmitted through an optical fiber (30).
) is projected from the condensing head (31).

Measurement using this concentration measuring device (C) is performed using the diffuser plate (21
), place the measurement sample (32) on the lower side of the diffuser plate (2), rotate the arm (23) downward, and move the condensing head (31) to the diffuser plate (2).
1) and manually rotate the disk (25) so that the desired filter (24) faces the light receiving element (27). The light from the reflection lamp (29) is transmitted through an optical fiber (3
0), is diffused by the diffuser plate (21), and is reflected to the measurement sample (32) 6. The reflected light is transmitted to the focusing head (31)
The light passes through the hole (3La) and the light guide cylinder (28) and is received by the light receiving element (27), and this density measuring device (C) is capable of measuring only the reflected density. Note that the output of the light receiving element (27) is sent from an output terminal (33) to an external data processing device and processed by a CPU or the like.

The density measuring device (CD) in FIG. 19 has a diffuser plate (3
4) into which the arm (36) is fitted.
) can move up and down (open and close) freely. The arm (3
In 6), the light from the reflective lamp (37) is projected from the condensing head (39) through the optical fiber (38).

The reflected light that enters the hole (39a) of the focusing head (39).

Four light receiving elements (42) are transmitted through four optical fibers (40) for transmitting reflected light and further through filters (41).
) is received. This density measuring device (D) independently measures the reflection density and displays the density value.

Problems to be Solved by the Invention The drawbacks of the above-mentioned conventional concentration measuring instruments (A) to D) are as follows.

(2) The method and process for attaching the light receiving element and the filter are complicated, and the costs associated therewith are high.

■ Unable to obtain uniform light.

■ Unable to measure reversal film.

■ Separate concentration measuring instruments for reflection and transmission are required, which requires a large installation area and increases costs.

■ Since it is manual, it is time consuming and requires skill to operate.

■ Automatic analysis of measured data is not possible.

■ Data processing for development management 1 Display, external output, etc. are not possible.

The object of the present invention is to overcome these drawbacks of the prior art.

All density measurements for photography (transmission density of color negative film, reflection density of color print, transmission density of color reversal film, transmission density of black and white film, reflection density of black and white print, transmission density of black and white reversal film) can be performed in one place. It can be done all at once using a single density measuring device and a single light-receiving element, and the measured data can be automatically analyzed and calculated, and the data can be displayed and output externally for development management. That's true.

Means for Solving the Problems In order to achieve these objects, the density measuring instrument of the present invention has three color filters for measuring the transmission density of color negatives, the reflection density of color prints, and the transmission density measurement of color reversal films. A disc with three color filters arranged at predetermined intervals in the circumferential direction, visibility filters for measuring the transmission density of black-and-white films, the reflection density of black-and-white prints, and the transmission density of black-and-white reversal films; A concentration measuring lamp, a transmitted density measuring lamp, one light receiving element, and the seven filters are connected to one light receiving element.
a motor that rotates the disks so that they face each other, a density measuring section that measures the density from the output of the one light receiving element, and a density difference that calculates the difference between the measured density and a reference density stored in a memory. a calculation unit, a color key correction value calculation unit that calculates a color key correction value from the difference, and a density key correction value calculation unit that similarly calculates a density key correction value;
an exposure time correction factor calculation section that calculates an exposure time correction factor from the color key correction value; a display section that displays the calculated color key correction value, density key correction value, and exposure time correction factor; and a display section that displays these data. It is characterized by being equipped with an interface for external output.

Function: According to such a density measuring device, by rotating the disk with a motor and selecting an arbitrary filter, both the reflected density and the transmitted density can be measured using the same single light-receiving element. Then, the difference between the measured density and the reference density is converted into a color key correction value, density key correction value, and exposure time correction factor and displayed on the display section. Moreover, these data can also be output to the outside from the interface.

EXAMPLE Next, an example of the present invention will be described first with respect to its mechanical and optical configuration.

In FIGS. 1 and 2, this concentration measuring device has a hollow arm (51) rotatably (openable and closable) pivotally attached to the rear end of the upper surface of a sample stage (50). Inside the sample stage (50), there is a transmitted density measuring lamp (52) located slightly below the top surface of the sample stage (50).
) is fixed, and the light from the lamp (52) is transmitted to the sample stage (
The light is diffused by a diffuser plate (53) made of opal glass or the like fitted into the upper surface of the light source (50), and transmitted upward.

Further, on the top surface of the sample stage (50), a transparent guide plate (54) made of transparent synthetic resin is positioned below the arm (51) and its rear end is fixed so that it can be rotated slightly up and down. It is worn. The transparent guide plate (54) has an inverted truncated conical ring-shaped aperture (54a) as shown in FIG.
55) is fitted.

On the other hand, inside the arm (51) is a reflection density measuring lamp (
56) and a condensing head (5
A plurality of optical fibers (
58), a motor (59), a disk (60) rotated by the motor (59), and one light receiving element (6
1) and are respectively arranged at predetermined positions.

As shown in FIG. 5, the disk (60) has seven filter holes (62) provided at predetermined intervals in the circumferential direction, and correspondingly eight stop position detection holes. (63) are similarly provided at predetermined intervals, and one fixed position detection hole (64) is provided at a predetermined position. This disk (60) contains three color filters (red, green, blue) for measuring the transmission density of color negatives, three color filters for measuring the reflection density of color prints and transmission density of color reversal film, and a black and white film. A total of seven filters (65), including one visibility filter for measuring the transmission density of the black-and-white print, the reflection density of the black-and-white print, and the transmission density of the black-and-white reversal film, are installed as follows.

That is, seven filters (65) are connected to the disk (60
) are held by filter fixing plates (66) in alignment with the filter holes (62) of the filter holes (62).

This filter fixing plate (66) is fixed onto the disk (60) by a retaining screw (67). The filter fixing plate (66) has seven filter holes (68) and eight stop position detection holes (69) like the disk (60).
) and one fixed position detection hole (70) are provided, and these holes are aligned with the corresponding hole on the disk (60) side.
They are matched one by one.

The eight stop position detection holes (63) are connected to the light emitting elements (72) attached to the sensor stand (71) as shown in FIG.
A stop position detection sensor (72) consisting of an opto-switch (72b) and an opto-switch (72b) detects the one facing the stop position detection sensor (72). Therefore, when one of the seven filters (65) faces the light receiving element (61), this is detected by the stop position detection sensor (72).

Further, one fixed position detection hole (64) is connected to a fixed position detection sensor (64) consisting of a light emitting element (73a) and an opto-switch (73b), which are similarly attached to the sensor stand (71).
73). That is, this home position detection sensor (73) detects that the disk (60) is set at the home position.

To use this concentration measuring device, place the measurement sample (S) on the sample stage (50) as shown in FIG.
A transparent guide plate (54) is brought into contact with the motor (59)
Rotate the disk (60) to select an arbitrary filter (
65). When measuring the transmission density, the transmission density measurement lamp (52) is turned on, and the light from the transmission measurement lamp (52) that has passed through the measurement sample (S) is passed through the aperture (55) and the condensing head ( hole (57)
7a) and further passes through a selected filter (65) and is received by a light receiving element (61).

When measuring 1 reflection intensity, the reflection density measuring lamp (56) is turned on, and the light is passed through the optical fiber (58) from the tip of the hole (57a) of the focusing head (57) to the aperture (55). The measurement sample (S) is irradiated through the beam.

The reflected light reflected from the measurement sample (S) is reflected from the aperture (55)
and the light receiving element (61) through the hole (57a) of the condensing head (57) and further through the selected filter (60).
) is received.

Therefore, with this density measuring device, the transmission density of a color negative film, the reflection density of a color print, the transmission density of a color reversal film, the transmission density of a black and white film, the reflection density of a black and white print, and the transmission density of a black and white reversal film can all be measured at the same time. The measurement can be performed all at once using multiple concentration measuring instruments, at the same location, and with a single light-receiving element (61).

The stop position and normal position of the disk (60) can be detected by detecting the protrusion (60) on the disk (60) as shown in FIG.
a) may be provided and detected by a light emitting element (74a) and an opto-switch (74b) attached to the sensor stand (71). In addition, if a step motor is used as the motor (59) that rotates the disk (60) and the number of steps is managed electrically, there is no need for sensors, holes, or protrusions for detecting the stop position and fixed position. It is.

Next, to explain the electrical configuration, FIG. 8 is a block diagram thereof, and all operations are managed by the CPU (75). In addition, in this example, the CPU (75) is
For convenience, the term includes an arithmetic processor.

The stop position detection sensor (72) and the fixed position detection sensor (73), a lamp control driver (76) that turns on and off the transmission density measurement lamp (52), and a lamp control driver (76) that turns on and off the reflection density measurement lamp (56). A lamp control driver (77) that drives the motor (59), a motor control driver (78) that drives the motor (59), a keyboard (79), a display board (80) using a liquid crystal, etc., a printer (81) such as a thermal printer, etc.
) are connected to the I10 boat (82), and these and the CPU
Signals are exchanged with (75) via the I10 decoder (83). Further, the analog output of the light receiving element (61) is amplified by a LOG amplifier (84), and the analog output of the light receiving element (61) is amplified by a LOG amplifier (84).
It is converted into a digital signal by a digital converter (85), further decoded by an I10 decoder (83), and the CP
It is supplied to U (75).

As shown in FIG. 9, the ROM (86) contains an I10 port and data initialization program, a density measurement program, a color key and density key correction calculation program, an exposure time correction calculation program, a slope correction data calculation program, and a calculation subroutine. Various programs such as the following are stored.

Further, in the RAM (87), storage areas and data storage areas for, for example, channels 1 to 10 are secured for various calculations to be described later. In each of the storage areas for channels 1 to 10, reference densities for each of the three colors red, green, and blue, and a V 5UAL (visual sensitivity) reference density are stored. The memory is stored on the keyboard (7
9) or by automatically measuring, for example, a reference control paper or film as described above, this RAM (87) is provided with a memory backup power supply (88). The operation data held and stored therein is sent to the I10 decoder (8
3) from an interface, for example, an R5-232G standard interface (89), to other external equipment as needed.

In this density measuring device, the main functions of the CPU (75) are as shown in FIG. 10. As shown in FIG. ), a density key correction value calculation section (93), and an exposure time correction factor calculation section (94).Next, the operation thereof will be explained with reference to a flowchart.

Figure 11 shows the main routine, first step (100)
Initialization of the I10 boat (82) and data is performed. After this, step (101) and step (1
02), the fixed position detection sensor (73) detects the fixed position of the disk (60), and if it is not in the fixed position,
That is, if the fixed position detection hole (70) of the disk (60) is not detected by the fixed position detection sensor (73), the disk (60) is rotated by the motor (59) in step (103). When the home position is reached, step (
At step 104), it is determined whether or not there is any key input from the keyboard (79), and if there is, the key processing at step (105) is performed. If there is no input, it is determined in step (106) whether or not the measurement start switch is input, and if the input is present, the concentration measurement process in step (107) is performed.

FIG. 12 shows a density key, color key correction value, and exposure time correction factor routine. When this routine is entered, first, in step (108), the visual density is measured using the visibility filter (65).

After that, step (109) instructs the motor (59) to rotate, step (110) detects the stop position, that is, the stop position detection sensor (72) detects the disk (60).
) detection of the stop position detection hole (63), step (1)
11) to determine whether or not the stop position is reached, step (112)
), the red filter (66) is selected, and the red density is measured in step (113).Next, the motor rotation command is similarly given in step (114), and the stop position is detected in step (115). , step (116) to determine whether or not the stop position is reached, step (11)
The green filter (65) is selected by stopping the motor in step 7), and the green density is measured in step (118). Subsequently, similarly, step (119) is a motor rotation command, step (120) is to detect the stop position, step (121) is to determine whether or not the stop position is reached, and step (
The blue filter (65) is selected by stopping the motor in step (122), and the blue density is measured in step (123).

Next, in step (124), the rotation of the motor (59) and the command to return the disk (60) to the normal position cause the disk (60) to be detected by the normal position detection sensor (73).
is rotated until the fixed position detection hole (64) is detected by. The following calculations are performed with the disk (60) thus returned to its home position.

That is, step (125) is performed in steps (10g), (113), and (11) for each of the visual density, red density, green density, and blue density.
8)・(123) and RAM (8)
7) The difference from the reference density stored in step 7) is calculated.

In the next step (126), color key corrections are calculated for the three colors red, green, and blue by multiplying the differences obtained in steps (1, 25) by variable constants. Note that this variable constant is
It is determined by the difference in VI 5UAL concentration determined in 25).

In step (127), the absolute values of the color key corrections for the three colors obtained in step (126) are compared, and the highest value is selected.

In step (128), a density key correction value is calculated by multiplying the maximum value determined in step (127) by a density key correction factor, which is a variable constant. Further, the color key correction values for the three colors are determined by subtracting the density key correction value from the color key correction for the three colors obtained in step (126).

In step (129), exposure time correction factors for the three colors are calculated by multiplying the color key corrections for the three colors obtained in step (126) by logarithmic variable constants.

After this, the mode is checked in step (130), and it is determined whether the mode is time mode or not in step (131).

If the time mode is selected, the process advances to step (132), and the exposure time correction factors for the three colors obtained in step (129) are displayed on the display board (80), and the data is displayed on the R3-232C in step (133). Interface (8
9) and further printed by the thermal printer (81) in step (134), the process returns to the main routine of FIG.

On the other hand, when not in time mode, step (135)
The density key correction value and the three color key correction values obtained in step (128) are displayed on the LCD, and the data is displayed on the R8-23 in step (136) in the same way as above.
After being output from the 2C interface (89) and printed by the thermal printer (81) in step (137), the process returns to the main routine.

Note that when the fixed position of the disk (60) is detected, the motor (59) is stopped by an interrupt as shown in FIG. 13, and then the process returns to the interrupt destination.

Through the processing shown in FIG. 12 as described above, the difference between the density reference value and the measured density value is converted into the color key correction value, density key correction value, and exposure time correction value for color and monochrome printing printers, and the values are It is displayed on the LCD and output to the outside.

Next, the slope correction routine shown in FIG. 14 will be explained. Note that slope correction refers to the adjustment of control negatives (normal negatives, overexposed negatives, and underexposed negatives) to AI
The purpose is to set up the exposure time of a color printing printer so that printing can be performed in M density.

By selecting the filter (65) in the same manner as in FIG. The measurement, the measurement of the green density printed from the normal exposure controlled negative in step (140), and the measurement of the blue density printed from the normal exposure controlled negative in step (141) are sequentially performed. After this, in step (142), with the disk (60) set at a fixed position, the difference between the measured density value and the reference density value is calculated for each of normal VISUAL, normal red, normal green, and normal blue. .

In the next step (143), color key corrections for normal exposure negative print management are calculated for each of the three colors by multiplying the differences between the three colors determined in step (142) by a variable constant.

In step (144), a density key for normal exposure negative print management is calculated by multiplying the maximum value of the color key correction for the three colors obtained in step (143) by a variable constant, and for each of the three colors. By subtracting the density key from the color key correction, three color color key correction values for normal exposure negative print management are calculated.

In step (145), three-color exposure time correction factors for normal exposure negative print management are calculated by multiplying the three-color color key correction obtained in step (143) by a variable constant.

In step (146), the exposure time correction factor or key correction value determined as described above is displayed on the liquid crystal display depending on the mode.

Next, the VISUAL density measurement printed from the overexposure controlled negative by step (147), step (147);
Measurement of red density printed from the overexposure controlled negative by step 148), measurement of green density printed from the overexposed controlled negative by step (149), and measurement of blue density printed from the overexposed controlled negative by step (150) are performed sequentially. It will be done. Then, in step (151), over VISUAL and over red.

For each of over green and over blue,
The difference between the measured concentration value and the reference concentration value is calculated.

In step (152), by multiplying the difference between the three colors obtained in step (151) by a variable constant,
Color key corrections for overexposed negative print management are calculated for each of the three colors.

In step (153), a density key for overexposed negative print management is calculated by multiplying the maximum value of the color key correction for the three colors obtained in step (152) by a variable constant, and for each of the three colors. By subtracting the density key from the color key correction, three color color key correction values for overexposed negative print management are calculated.

In step (154), three-color exposure time correction factors for overexposed negative print management are calculated by multiplying the three-color color key correction obtained in step (152) by a variable constant.

In step (155), the exposure time correction factor or key correction value for overexposed negative print management determined as described above is displayed on the liquid crystal display depending on the mode.

Next, the VISUAL density measurement printed from the underexposure controlled negative by step (156), step (156);
Measurement of red density printed from the underexposure controlled negative by step 157), measurement of green density printed from the underexposed controlled negative by step (158), and measurement of blue density printed from the underexposed controlled negative by step (159) are performed sequentially. It will be done. Then, in step (160), the difference between the measured density value and the reference density value is calculated for each of undervisual, underred, undergreen, and underblue.

In step (161), by multiplying the difference between the three colors obtained in step (160) by a variable constant,
Color key corrections for underexposed negative print management are calculated for each of the three colors.

In step (162), a density key for underexposed negative print management is calculated by multiplying the maximum value of the color key correction for the three colors obtained in step (161) by a variable constant, and for each of the three colors. By subtracting the density key from the color key correction, three color color key correction values for underexposed negative print management are calculated.

In step (163), three-color exposure time correction factors for underexposed negative print management are calculated by multiplying the three-color color key correction obtained in step (161) by a variable constant.

In step (164), the exposure time correction factor or key correction value for underexposed negative print management determined as described above is displayed on the liquid crystal display depending on the mode.

When the normal, over, and under processing as described above is completed, the measurement is completed in step (165), a mode check is performed in step (166), and it is determined whether the mode is time mode or not in step (167). will be judged. In the case of time mode, step (168
), the exposure time correction factor data obtained as described above for each of the normal negative exposure time correction factor, over negative exposure time correction factor, and under negative exposure time correction factor is read out from RAM (87). In addition, when not in time mode, the three color color key correction data and density obtained as above for each of the normal negative exposure time key correction value, over negative exposure time key correction value, and under negative exposure time key correction value Key correction data is read. These data are then transferred to the R8-232C interface (89) in step (170).
) and is further printed by the thermal printer (81) in step (171), after which the process returns to the main routine.

Although not shown in FIG. 14, during each measurement process, as shown in FIG. Determining whether or not it is at the stop position, step (1)
Step 75) of motor stop processing and determination is performed.

Therefore, this concentration measuring instrument can be used for reference concentration values or AI
M concentration values can be stored in each channel of RAM (87) manually by key input or by reading the reference concentration. The difference between the stored reference density and the measured density value is the correction value (red, green, blue time value) for exposure time correction of the color printing printer or the color key (red, green, green time value) for exposure time correction. , blue) and density key correction values can be converted, displayed, and output externally.

Further, color printing printers have different correction rates for color keys and density keys depending on the model and manufacturer, but the color one-time correction rate and the waiting time correction rate can be changed manually.

Furthermore, by switching the output mode, slope correction data (exposure time correction factors for red, green, and blue or color and density key correction values) for normally exposed negatives, overexposed negatives, and underexposed negatives of color printing printers is also displayed. and can be output externally.

Effects of the Invention As detailed above, according to the density measuring device of the present invention, by rotating the disk with a motor and selecting an arbitrary filter, the transmission density of a color negative, the reflection density of a color print, and the transmission of a color reversal film can be measured. All density measurements of density, transmission density of black and white film, reflection density of black and white print, and transmission density of black and white reversal film are performed in the same one
It can be measured using several light-receiving elements. Therefore, the work of measuring reflection density and transmission density is simplified, the number of parts is reduced, and the installation area is also reduced, so that it can be provided at low cost and downsized. Furthermore, since the measurement conditions of the optical system are also uniform, accuracy is also improved. Furthermore, the difference between the 1 m degree measurement and the reference density can be converted into a color key correction value, density key correction value, and exposure time correction factor and displayed on the display section, and these data can also be outputted to the outside from the interface.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the concentration measuring device according to the present invention, Fig. 2 is a plan view thereof, Figs. 3 (A) and (B) are a plan view and a sectional view of the transparent guide plate, and Fig. 4 (A). and (B) are a plan view and a sectional view of the aperture, FIG. 5 is an exploded perspective view of the filter, filter fixing plate, and disk, FIG. 6 is a front view showing the relationship between the disk and the sensor, and FIG. 7 is the other FIG. 3 is a front view of an example. FIG. 8 is a block diagram of the electrical configuration of this concentration measuring instrument, FIG. 9 is its memory map, FIG. 10 is a block diagram of the CPU broken down into its functions, and FIGS. 11 to 15 are its flowcharts. Further, FIGS. 16 to 19 are sectional views of conventional examples, respectively.

Claims (1)

[Claims] Three color filters for measuring the transmission density of color negatives, three color filters for measuring the reflection density of color prints and the transmission density of color reversal films, measurement of the transmission density of black and white films, the reflection density of black and white prints and the transmission density of black and white reversal films. A disk having visibility filters arranged at predetermined intervals in the circumferential direction, a reflection density measurement lamp, a transmission density measurement lamp, one light receiving element, and the seven filters. a motor that rotates the disk so as to face the one light receiving element one by one;
A density measurement section that measures the density from the output of the one light receiving element, a density difference calculation section that calculates the difference between the measured density and a reference density stored in the memory, and a color key correction value calculated from the difference. a color key correction value calculation section that calculates a density key correction value, a density key correction value calculation section that similarly calculates a density key correction value, an exposure time correction factor calculation section that calculates an exposure time correction factor from the color key correction value; What is claimed is: 1. A photographic density measuring device, comprising: a display section that displays color key correction values, density key correction values, and exposure time correction factors; and an interface that outputs these data to the outside.