JPS6340129A - Image inverting method - Google Patents

Abstract

PURPOSE:To optimize the brightness of an image which has been inverted, and also, to vary no brightness even if gamma is converted, by varying no standard gray level at the time of the inversion. CONSTITUTION:At the time of inverting an image which has been brought to an image pickup by a camera 30, from a negative image to a positive image, or from a positive image to a negative image, it is executed so that a standard gray level is not varied at the time of the inversion. Also, in order to maintain the brightness of the whole screen so as to be constant in case the negative image and the positive image have been inverted, it is desirable especially that the standard gray level in which the brightness is not varied at the time of inversion of the negative image and the positive image is set to about 23% of a white level. In this way, the standard gray level, namely, brightness of a point of a neutral density is not varied, therefore, brightness of the whole screen becomes optimum.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image reversal method, and particularly to a finished print obtained by reversing an image recorded on a negative film and printing it onto photographic paper using an automatic photographic printing device. This invention relates to an image reversal method for a simulator that displays the same image on a CRT.

[Conventional technology]

Conventionally, the integrated transmission density (LATD) of the entire image of a color negative film is measured, 4 degrees of correction is performed, and slope control is performed to ensure that the density and color balance of all finished prints are as good as the light and shade (n-light under, appropriate). Color automatic photographic printing (WW) is known, which prints and develops images so that they are the same regardless of exposure or overexposure. This automatic photographic printing apparatus is constructed by sequentially arranging an optical system including a light source, a light control filter, a mirror box, a negative carrier, and a black shutter. Printing is performed by placing a color negative film on a negative carrier, turning on a light source, opening a black shutter, and forming an image of the color negative film on photographic paper. The printed photographic paper is configured such that the print is automatically completed by being developed by a development process. In this automatic photo printing device, the light that has passed through the negative film is detected by a light receiving element such as red light (R), green light (G), and blue light (
B) primary color separation and LATD based on Evans' theorem.
The color balance is controlled by controlling the angle of 174 degrees using JJ and performing slope control so that the slopes are the same for the three primary colors. Therefore, with this automatic photoprinting apparatus, all normally finished prints have the same density and color balance.

However, even if the main subject of a color negative film has a suitable level of agriculture, if the background has a dark or light background color, it may cause problems with this background. Since the exposure amount is controlled based on the influence of one degree, density fetch occurs.

Furthermore, when the color balance of the main subject is different from the color balance of the background, for example, when the color of the main subject and the color of the background are complementary colors, a color area occurs. Therefore, even if density correction and slope control are performed, the quality of the print may deteriorate. In this way, if the finished state of the print deteriorates, it becomes necessary to carry out printing and development again.

For this reason, conventionally, as shown in Japanese Unexamined Patent Publication No. 53-46731, it is possible to obtain the desired 74 degrees and color balance by re-imaging a negative film image with a TV camera and displaying the image on a TV screen. A so-called photographic verification device is used in which a color video signal is adjusted and printed using an automatic photographic printing device.

In addition, as shown in Japanese Patent Publication No. 42-25220, there is also a system in which an image of a negative film printed on photographic paper is displayed on a TV screen, and an automatic exposure machine is linked with a resistor for adjusting the brightness and contrast of the TV. be. In this way, the frequency of reprinting and development processing is reduced.

When inverting a negative image into a positive image using the above-mentioned conventional device, it is possible to invert the black and white rails with respect to y=-x (x, y are coordinate values when the density area is expressed in Xy coordinates). It is being said.

[Problem that the invention seeks to solve]

However, in cameras and TVs, O~0.
7■ displays from black level to white, so if you invert the white level to black level and the black level to white level with respect to y = -x, the logarithm of the black level is -(3), and the black level can be converted to a finite value. There is a problem in that it is not possible to convert to a white level, and it is not possible to perform negative/positive inversion with an appropriate gradation.

The present invention was made in order to solve the above-mentioned problems, and an object of the present invention is to provide an image reversal method in which the brightness of an image becomes appropriate when the image is reversed.

[Means for solving problems]

To achieve the above object, the present invention is characterized in that when an image captured by a camera is reversed from a negative image to a positive image or from a positive image to a negative image, the standard gray level does not change during the reversal. .

In addition, in order to keep the brightness of the entire screen constant when a negative image and a positive image are reversed, a standard delay level that does not change in brightness when reversing a negative image and a positive image must be set at 23% of the white level.
It is particularly preferable to set it to around %.

[Effect]

In the present invention, when reversing a negative image and a positive image, the standard dazzling level does not change.

As a result, the brightness of the standard gray level, that is, the point of neutral density does not change, so that the brightness of the entire screen is optimized. According to experiments conducted by the present inventor, it was found that 23% of the white level of the camera output is optimal as the standard gray level.

[Effects of the Invention] As explained above, according to the present invention, since the image is inverted so that the standard gray level does not change, the brightness of the image after inversion is optimized, and γ is converted. Also, since the brightness does not change, it is easy to perform γ correction.

[Example] A device to which the present invention is applicable will be described in detail below with reference to the drawings. This device is a combination of a color automatic photo printing device (hereinafter referred to as a printer) and a device (hereinafter referred to as a simulator) that displays images cast on color negative film in the same state as they are printed by the printer.

As shown in Figure 1, light a composed of a halogen lamp
On the back side of 10, there is a reflecting mirror 1 composed of a cold mirror.
2 is placed. A voltage of approximately 90% of the rated voltage is supplied to the light a10 from a power supply device (not shown) in order to prolong the life of the light #tIO and obtain a predetermined color temperature. On the light irradiation side of the light source 10, there are Y (yellow) filter plates each configured by combining two fan-shaped filter plates of approximately 1/4 circle formed by a logarithmic curve and arranging them in pairs on the left and right.
A light control filter 14 consisting of M (magenta) and C (cyan) color filters and a mirror box 16 equipped with a scattering plate are arranged in this order, and the light rays emitted from the light tA10 are transmitted through the light control filter 14. After the color balance and light amount are adjusted, the mirror box 6 converts the light into uniform diffused light, and the diffused light is irradiated onto the color negative film 18 held on the negative carrier. To adjust the above light source voltage, set each complementary color filter of the dimmer filter to the mechanical center, measure the light amount with a luminometer, and adjust it to a constant light amount (standard exposure time). Adjust so that 90% of the voltage is supplied.

An optical system 2o and a black jack 22 are arranged in this order on the transmitted light beam exit side of the color negative film 18, and when the black gloss 22 is opened, the color negative film 1
The light beam transmitted through the image forming apparatus 8 forms an image on the photographic paper 24 and exposes the photographic paper. The exposed photographic paper 24 is processed in a development process 25 and then printed 2
It is said to be 7.

A drive circuit 26 is connected to the light control filter 14, and the drive circuit 26 moves each of the complementary color filters in a direction perpendicular to the optical axis, thereby making it possible to adjust the color balance and light amount. Further, a drive circuit 29 is connected to the black shutter 22 .

Near the 20 optical systems of the color negative film 18, R
Equipped with three filters that transmit (red) light, G (green) light, and B (blue) light, respectively, and outputs R, G, and B signals.
Camera 30 composed of a board camera and 3 of R, G, and B
An image information detection device 32 equipped with a two-dimensional image sensor for detecting image density information of primary colors is arranged.

This two-dimensional image sensor is a CCD (charge coupled device)
It consists of Note that the camera 30 may be configured with a single CCD camera.

Here, in a normal TV system, T of the TV is set to be about 2.2 for good visual visibility, so a γ correction circuit with γ = 0.45 is installed in the TV camera, so that r =
1, but in normal printing γ=2
．． In this embodiment, the γ correction circuit is not provided in the camera 30, and γ in the simulator is set to approximately 1, and together with the γ value of the CRT, the overall result is γ#.
I'm trying to set it to 2.0.

The camera 30 is connected to a simulator 34 via a gain control circuit 33, and the image information detection device 32 is connected to a slope control circuit 62 via a δ and γ correction circuit 38 and a printing system density calculation circuit 40. has been done. The printing system density calculation circuit 40 and the slope control circuit 62 perform the color balance and density correction described above. Further, a chromaticity meter 42 is arranged to face the screen of the CRT 345 constituting the simulator 34, and a chromaticity meter 44 is arranged to face the screen of the print 27. The color meters 42 and 44 are connected to the ■/○ ports 46 that constitute the computer. Computer C, above I10 port 46, CPt
J4B, read-only memory (ROM) 50, random access memory (RAM) 52, digital-analog (D/A) converter 54, analog-digital (A/D
) converters 56 and 58 and buses 60 such as data buses and control buses that connect these converters, and a gain control circuit 33, a simulator 34, a δ and γ correction circuit 38, and a printing system density calculation circuit 40. It is connected to the connected slope control circuit 62 and drive circuit 26, and is also connected to the drive circuit 29.

The gain control circuit 33 is composed of an amplifier 331, an operational amplifier 332, a flip-flop 333, and resistors 334 to 336, as shown in FIG. A reference voltage (0.7V corresponding to the white level) is input. In order to adjust the gain of the camera 30 using the gain control circuit 33, the camera 30 takes an image of a w table negative (so-called plain negative) obtained by developing an unphotographed film, and outputs the camera output in each of the three primary colors of R, G, and B. This is done by outputting an analog signal from the D/A converter 54 and stopping the gain adjustment when the signal is output from the flip-flop 333. This allows the white level of the camera to be adjusted when the blank is negative (when the transmitted light of the negative is at its maximum), making it possible to accurately and easily determine the brightness standard.

In addition, the iris position and color balance position of the camera after the gain has been adjusted as described above can be stored as digital values, and the change can be made for each different type of negative film or negative size (the amount of light changes because the magnification is different). By converting the channels into a single channel, you can change the channel by simply switching the channel each time you change the negative.

By doing this, even if the type of negative film or negative size changes, the iris position and color balance position of the camera can be changed simply by switching channels. In the above case, if the light source deviates from the standard state, it will be necessary to electrically correct the deviation.
It is preferable to adjust the light source so that a standard gray negative produces a standard gray print.

As shown in FIG. 3, the third δ and γ correction circuit includes a signal processing circuit 60 which converts the R signal output from the image information detection device 32 into a density signal and performs δ and γ correction. It is comprised of a signal processing circuit 62 that converts the G signal into a density signal and performs δ and γ correction, and a signal processing circuit 64 that converts the B signal into a density signal and performs δ and γ correction. These signal processing circuits 60
．． 62 and 64 have the same configuration, so the signal processing circuit 60
will be explained only. The signal processing circuit 60 includes an offset correction circuit 601 and a logarithmic conversion circuit 6 for converting the density signal.
02, a δ correction circuit 603 and a γ correction circuit 604. The offset correction circuit 601 includes an operational amplifier OP3, resistors R6 and R7, and a variable power supply B1. The δ correction circuit 603 includes an operational amplifier OP4, resistors R6 and R7, and a variable power supply B2. Then, the R, G, and B signals are corrected by δ and γ and output.

The above simulator 34 uses a logarithmic converter 341 connected to the output terminal of the gain control circuit 33 to match the density (integral density) seen from the spectral sensitivity of the camera with the density seen from the spectral sensitivity of the photographic paper. Matrix (cubic square matrix)
A circuit 342, an N/P inversion circuit 343 that inverts negative/positive (N/P) and converts it to the analytical density of photographic paper, and a luminance signal conversion circuit that converts the analytical density of photographic paper to the analytical brightness of the CRT phosphor. 344 and a CRT 345 that displays an image drawn by the camera 30 by coloring a phosphor according to the output of the luminance signal conversion circuit 344 are connected in series.

Receiving ＼, correction of sensitivity Here, the value obtained by logarithmically converting each of the B, G, and H signals output from the camera 30 by the logarithmic conversion circuit 341, that is, the integrated density of the color negative film image seen from the spectral sensitivity of the camera is calculated as BTV. % G'yv and R'tv are converted into negative analytical density using a 3×3 matrix A-' (where -1 indicates an inverse matrix) as shown in the following equation.

Further, when the integral density of a color negative film image viewed from the spectral sensitivity of the photographic paper is converted into an analytical density of a negative using a 3.times.3 matrix 3-1 using BP, Gy, and Rp, the following equation is obtained.

Negative analytical density (Btv
, G r v - R tv ) and (BP , Gp ,
Since it is proportional to Rr), it is expressed by the following equation (3) using a diagonal matrix α whose diagonal components are proportional constants.

Therefore, using equations +11 to (3) above, (B, , Gp
, RP) and (B tv, G'rv, R'rv), the following equation (4) is obtained.
The density determined by the spectral sensitivity of the photographic paper is converted to the density determined by the spectral sensitivity of the photographic paper.

The components of each of the above matrices B and α are determined in advance for a sample such as a reference negative, taking into account the coloring characteristics of the color negative film, the spectral sensitivity characteristics of the photographic paper, and the spectral sensitivity characteristics of the camera, and the matrices shown below are x3 matrix circuit 342.

The N/P inversion circuit 343 is a circuit that converts T to -T, and converts the output of the 3×3 matrix circuit 342 according to the following straight line and outputs the converted signal.

'/ Y+ = a (x-X, )...(6)
where,
The coordinate value a when expressed by the y coordinate is a constant, and a negative value is usually selected.

As the pivot point, a point where the density should not change even if N/P is reversed, that is, a point at a neutral gray (standard gray) level, is selected.

Cameras and CRTs display the range from black level to white level at 0 to 0.7V, so when the camera output is logarithmically converted, the black level becomes -■. For example, the black level may not be accurately inverted to the white level. For this reason,
For N/P inversion, the camera output ■, 23% of the white level of 1 (density excluding the base of the negative is 0.63)
) is preferably used as a pivot point for N/P inversion.

Figure 4 shows the camera output y i when N/P is inverted with 23% of the white level of the camera output Via as the pivot point.
++ and N/P inversion circuit 343 output ■. The relationship with □ is shown. Since the white level of the camera is 0.7V, 23% of the white level is 0.161V.

Here, the output of the 3×3 matrix circuit 342 is expressed as Y =
3.2518 + 10gVt++・=(If expressed as 71, the coordinates corresponding to 23% of the white level are (0,16L
2.47). Therefore, the straight line passing through (2,47,2,47) y -2,47= a (x-2,47)...(8
), converting the curve represented by (7) 2 above yields the curve shown in FIG. 4, which is N/P inverted. As understood from FIG. 4, the value of 23% of the white level of the camera output remains unchanged even after the N/P inversion.

Further, in order to perform N/P inversion, the N/P inversion circuit may be configured with the circuit shown in FIG. 5, and the N/P inversion may be performed by finding a pivot point as described below. The circuit in Fig. 5 is constructed by floating the contactor of the variable resistor R1 and the variable resistor R1, which sets the operational amplifier OP1.0P2, the reference voltage of the operational amplifier, ■, and ■y (corresponding to the pivot point). It is equipped with an actuation mechanism AC that changes the A signal is input to the inverting input terminal of the operational amplifier OPI via a resistor R2, and a variable resistor R3 for adjusting the gain is connected between the inverting input terminal and the output terminal of the operational amplifier OP1. The output terminal of the operational amplifier OPI is connected to the inverting input terminal of the operational amplifier OP2 via a resistor R4. A resistor R5 is connected between the inverting input terminal and the output terminal of the operational amplifier OP2. Variable resistor R1
One end is grounded, the other end is grounded via power supply B, and the contact of the variable resistor R1 is connected to the operational amplifier OP1. They are each connected to the non-inverting input terminal of OP2.

A method for determining the pivot point using the above circuit will be explained. First, a color negative film colored in standard gray is held between negative carriers and layered with a camera, and after N/P inversion is performed using the circuit shown in FIG. 5, it is displayed on a CRT screen. next,
A standard gray signal is electrically generated (by setting the white level of the CRT to 23%) and displayed on the CRT screen in close proximity to the above-mentioned negative image. Then, by operating the keyboard, the resistance value of the variable resistor R1 is continuously changed to change the reference voltages V, , V, and a negative image colored in standard gray is electrically created using a standard gray signal. match.

As a result, the pivot point is determined to be around 23% of the white level of the camera output.

By using the above circuit, it is possible to set the gray level according to the sense of the measurer, and since it is possible to set the gray level according to the sense of the measurer, it is possible to match the finished state of the print. The gray level can be set, and thereby a highly accurate simulation can be performed including conditions such as development conditions (fatigue of the developer, temperature change of the developer, etc.).

In addition, since a CRT with corrected "multidimensional" characteristics displays an image using a light emitter, the brightness of the CRT is proportional to the voltage. However, since photographic paper uses an absorber (dye), the amount of dye is not proportional to brightness, but the amount of dye is proportional to the logarithm of brightness, and furthermore, changing the amount of dye changes the chromaticity point. Change. In other words, the pigments in photographic paper are unstable primary colors (the chromaticity point of which changes depending on the amount of pigment).
C, Y, M).

Therefore, the luminance signal conversion circuit 344 has N
The /P inversion circuit 343 output is converted into an analysis type signal T and output to the CRT 345.

T=F (Ilog-' CI (D)) )...
(9) where f is a function that converts the output into an integrated density, and F is a function that converts the integrated transmittance log-' (D) into an analytical luminance signal.

The functions F and f are determined by determining the output value and the analytical luminance signal T to optimal values in advance, and performing optimization using the least squares method, regression, or the like. Note that for the functions F and f, a 3×3 matrix is used for boat fishing.

Then, the CRT is controlled by the luminance signal obtained by the luminance signal conversion circuit 344 as described above, and the CRT is
, T, an image having coloring characteristics matching those of the photographic paper is displayed.

Note that although an example in which a negative image is inverted into a positive image has been described above, the present invention is not limited to this, and can also be applied to a case in which a positive image is inverted into a negative image.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a device to which the present invention can be applied, FIG. 2 is a circuit diagram showing an example of the gain control circuit of FIG. 1, and FIG. 3 is a block diagram of an example of the gain control circuit of FIG. 1. A circuit diagram showing an example, FIG. 4 is a diagram for explaining N/P inversion, and FIG. 5 is another circuit diagram for performing N/P inversion. 14...Dimmer filter, 27...Print, 34...Simulator.

Claims (2)

[Claims] (1) An image inversion method characterized in that when an image captured by a camera is inverted from a negative image to a positive image or from a positive image to a negative image, the standard gray level does not change during the inversion. (2) The image inversion method according to claim (1), wherein the standard gray level is approximately 23% of the white level of the camera.