JP2720967B2 - Color negative film reader - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color negative film reader for digitally reading a color negative film and performing color correction on the obtained color image data. [Prior art] Conventionally, as a color negative film reader that reads a color negative film and outputs it as R, G, B density signals, a commonly used silver halide print system or a large-scale digital There is a scanner writer, etc. However, in general, the color balance of an image on a color negative film varies greatly depending on the lighting conditions at the time of shooting, and the film itself is also a negative image and orange masked, so that the true color tone of the subject can be visually observed directly from the film. It was almost impossible to judge. Therefore, in the above-described conventional apparatus, Y
(Yellow), M (magenta), C (cyan) optical filters, or silver halide prints while appropriately changing the R, G, B ratio of the digital processing system. Output, or the like, so as to obtain an image output with a preferable color balance. Therefore, the adjustment requires a skill and a considerable amount of work for the operator. [Problems to be Solved by the Invention] However, the above-mentioned changes in the lighting conditions at the time of film shooting can be roughly classified into changes in the color temperature (or correlated color temperature) of natural light in the outdoors and changes in the indoors. This is a change in the type of artificial light such as a fluorescent lamp or a halogen bulb. Since the spectral distribution of these light sources is generally known in advance, the color balance of an image on a color negative film is predicted from the type of light source at the time of shooting. It is conceivable that it is also possible to predetermine appropriate tuning parameters based on the prediction. In view of the above-described problems, the present invention provides a color negative film reading device that can easily correct the color balance of a color negative film with a simple circuit configuration without requiring special skill of an operator. With the goal. [Means for Solving the Problems] To achieve the above object, a color negative film reader according to the present invention is an input means for inputting color image data obtained by reading a negative film photographed under certain photographing conditions. Storage means for storing a plurality of color correction data corresponding to the shooting conditions; determining means for determining the certain shooting conditions based on the color image data input by the input means; and the determined shooting conditions Selecting means for selecting desired color correction data from among the pieces of color correction data stored in the storage means on the basis of the color correction data selected by the selecting means; Color correction means for performing desired color correction. [Operation] In the present invention, with the above configuration, a negative film photographed under a certain photographing condition is read, the certain photographing condition is determined based on the input color image data, and stored in the storage unit based on the determined photographing condition. Since the desired color correction data is selected from the stored data and the desired color correction is performed on the input color image data using the selected color correction data, the operator does not need to be skilled. It is possible to perform color correction according to shooting conditions, and to appropriately correct the color balance of a color negative film shot under certain shooting conditions. [Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a circuit configuration of a first embodiment of the present invention. In this figure, 101 is an illumination light source that proves a color negative film, 102 is a condensing lens that collects light rays of the light source 101, 103 is a cyan filter that corrects the orange base color of the color negative film to some extent, and 104 is a color negative film to be read. is there. 105 is an image forming lens for forming an optical image of the color negative film 104, and 106 is an in-line type solid-state image sensor CCD in which filters of three colors of R, G, B are alternately arranged.
(Charge imaging element) 107 is an A / D converter that samples and holds the output of the CCD 106, amplifies it at a fixed amplification rate, and A / D converts it to output R, G, B digital data. Reference numeral 108 denotes a shading RAM (random access memory) for removing unevenness in the sensitivity of the output of one line of the CCD 106 (unevenness), unevenness in the amount of light of the illumination light source 101, and an orange-based color of the color negative film 104, as described later. 109 is a multiplication type shading correction circuit for the same purpose. 110-R, 110-G, and 110-B are tables for performing logarithmic conversion of R, G, and B signals (hereinafter, referred to as standardized signals) after shading correction by the shading correction circuit 109, respectively.
ROM (read only memory), 111 is R after logarithmic conversion
(Red), G (Green) and B (Blue) signals are subjected to black extraction and UCR (under color removal) processing by a known method.
A UCR processing circuit for obtaining Y (yellow), M (magenta), C (cyan), and K (black) signals. 112 performs a matrix operation on the Y, M, and C signals output from the UCR processing circuit 111, and finally outputs Y ', M', and C 'to the printer 113.
This is a masking circuit for obtaining a signal. As the printer 113, for example, a color printer such as a laser beam printer capable of outputting a color multi-valued image of Y, M, C, and K colors is used. In the above configuration, the film 104 is fed at a constant speed in the direction of the arrow in FIG.
Although an image is output by the printer 113 for each scanning line, the image may be read by scanning the optical system of the imaging lens 105 and the CCD 106 in the direction of the arrow in FIG. Further, the above-described shading correction circuit 109 is a CCD 106
This is to remove the unevenness in sensitivity, uneven light intensity of the light source 101, and the color of the orange base (the portion of the film 104 that has been unexposed and developed) that differs for each film 104. First, the orange base portion of the color negative film 104 is removed. The R, G, B signal outputs for one line of the CCD 106 with the (orange base film) placed thereon are written in the shading RAM 108 in advance for each pixel. Note that the data stored in the RAM 108 is R, G,
For each of B, S _R (x), S _G (x), S
_B (x) (x is the coordinate value of the CCD 106 in the main scanning direction). Next, an image film to be actually read is set as the color negative film 104 to be read, and the image data read in the same manner as described above is read for each of R, G, and B for I _R (x) and I _G (x). , when you write I _B (x), when using an image signal of 8 bits for the shading correction circuit 109, performs the following calculation formula (1), the normalized signal
N _R (x), _NG (x), and N _B (x) are obtained and sent to the logarithmic conversion table ROMs 110-R, 110-G, and 110-B at the next stage. By performing the operation of equation (1), N _R (x), N
_{G (x), N B (} x) is the data that does not depend on the color of orange-based color negative film 104 pixels and use the CCD 106. Logarithmic conversion table ROM110-R, 110-G, 110-B , the above-mentioned normalized signal _{N R (x), N G} (x), N B a (x) R, G, density signal B (or, (C, M, Y signals). In general,
The gradation of the color negative film follows a characteristic curve called an HD curve as shown in FIG. In FIG. 2, the transmission density of the film is a value obtained by setting the above-mentioned normalized signal N to -logN. Therefore, in order to obtain signals D _R , D _G , and D _B that are inversely proportional to the object density from the normalized signals N _R , N _G , and N _B , the following equations (2), (3), and (4) It turns out that such a conversion should be performed. Here, the density in the range of the subject density range ΔD is 8 bits (0
~ 255), and γ _R , γ _G ,
gamma _B linear portion of the R of the H-D curve of Figure 2, G, and the slope of B respectively, also W _G, W _B is a film obtained by photographing a white object R,
G, transmittance T _R ^W of B, T _G ^W, obtained from T _B ^W. As ^{_{W G = T G W / T}} R W W B = T B W / T R W, the aforementioned D _R, D _G, is D _B is a value determined. FIG. 3 shows an example of the characteristic curve of the density signal obtained by the above equations (2), (3) and (4). Curve 31 in this figure is (2)
D _{R in} the equation, curve 32 is D _G in equation (3), and curve 33 is D _{B in} equation (4)
Is represented. D _R , D _G , in equations (2), (3) and (4)
Data and the normalized signal N _R of D _B, N _G, the relationship between the N _B is, LUT
ROM 110-R, 110-G, 110 as (lookup table)
Are written in advance to -B, in this case N _R, N _G, table conversion of 8-bit data as a read address to N _B is performed, the D _R, D _G, the value of D _B are read become.
Here, equation (2) is ROM110-R, equation (3) is 110-G,
Equation (4) corresponds to 110-B. Next, a description will be given of a process performed when a film imaging condition changes. For example, there is a phenomenon that images taken in the morning and evening become reddish, and images taken in snowy mountains and the like become bluish. This development is based on the color temperature of the illumination light (sunlight in this case) at the time of photography. Changes, and R, G, B of the light source
This is caused by the fact that the ratio of the components changes, and the HD curve in FIG. 2 moves right and left independently of R, G, and B independently. Therefore, in order to correct this discoloration phenomenon, the third
The values in the density conversion table in the figure, or (2), (3),
It is necessary to appropriately change the value of the expression (4) according to the shooting conditions of the film. Here, the ratio of R, G, B components of sunlight outdoors on a sunny day is normalized to be 1: 1: 1. Under certain shooting conditions, the ratio becomes 1: k _G : k _B. Then, the subject density signals D _R ′, D _G ′, and D _B ′ are (2),
It can be seen that D _R , D _G , and D _{B in} equations (3) and (4) require further correction as in the following equation. FIGS. 4 (A) to 4 (E) show the color temperature of the photographing light source at 8000K and 65K.
The density signals D _R ′, D _G ′, and D _G ′ of formulas (5), (6), and (7) are obtained from the values of k _G and k _{B when} the values are changed to 00K, 5500K, 5000K, and 4500K.
D _B 'between the normalized signal N _R, N _G, shows a graph plotting the relationship between the N _B. The curve of 41 is 8000K and the curve of 42 is 650, respectively.
0K, 43 curve is 5500K, 44 curve is 5000K, 45 curve is 45
This shows characteristics at a color temperature of 00K. Therefore, the logarithmic conversion table ROM 110-R, 110-
G, 110-B stores in advance a plurality of patterns as shown in FIG.
If one pattern (table) is selected, the fluctuation due to the color temperature of the photographing light source can be appropriately corrected, and the R, G, B density signals always having the same color balance can be obtained. . Here, the address switching signal 114 is set by an operator using a manual switch, or
Color negative film 10 by reading scanning system such as CCD106
The film image of No. 4 may be pre-scanned (pre-scanned) to read the shooting state of the film image and automatically switch. FIG. 5 shows an example of the operation unit when the address switching signal 114 is manually generated by the operator as described above. When the pointer of the dial switch 61 in this figure is changed from the standard position to redness correction 1, 2, 3 and blueness correction -1, it corresponds to the five logarithmic conversion tables of FIGS. 4 (A) to 4 (E). Address switching signals 114 are sequentially generated. in this case,
If the logarithmic conversion table having the contents shown in FIG. 4 is used, redness correction can be performed on an image having a low color temperature of the light source at the time of shooting, and bluish correction can be performed on an image having a high color temperature of the light source at the time of shooting. . FIG. 6 shows a circuit configuration of a second embodiment of the present invention. In this figure, 101 to 113 are the same as those in FIG. 514-R, 514-G, and 514-B are variable-gain analog amplifiers, each having a CPU (Central Processing Unit).
The digital value given from 15 is converted into an analog value by, for example, a built-in multi-blind D / A converter, and the output of the CCD 106 is amplified at a predetermined amplification factor corresponding to the analog value. Reference numeral 516 denotes a switching signal similar to the address switching signal 114 in FIG. 1, and a digital value to be transmitted to the analog amplification bases 514-R, 514-G, and 514-B is determined in the CPU 515 in accordance with the value of the switching signal 516. It is obtained by calculation. By the way, when the equations (2), (3) and (4) are substituted into the above equations (5), (6) and (7), the following equations (8),
(9) and (10). (8), (9), (10) and (2), (3), comparing (4), (2), (3), (4) the N _R, N _G, N _B
The ^{_{N R, k G γG, N}} G, k B γB, by replacing the N _B,
Equations (8), (9), and (10) are obtained. That is, by amplifying the normalized signals N _R , N _G , and N _B to 1 time, k _G ^γ _G times, and k _B ^γ _B times, respectively, the case where the equations (5), (6), and (7) are used is The same result will be obtained. Therefore, as in the first embodiment, when a switching signal 516 is input from a dial switch or the like, the CPU shown in FIG.
515, according to the value of the switching signal 516, k _G ^.GAMMA.g which is stored in ^advance, k _B ^.gamma.B by selecting one of a set of values of the analog amplifier 514G, the amplification factor of the 514B is the k _G ^.GAMMA.g obtains a digital value that equals the k _B ^.gamma.B, if the input to the multiplying D / a built-in analog amplifier, the same effects as in the first embodiment can be obtained. Here, the analog amplifier
Of the 514-R, 514-G, and 514-B, it was described that 514-R was not used. However, in fact, the initial state of the amplification factor of the analog amplifier was α times for both R, G, and B. For example, the switching signal 516 causes the amplification factors of R, G, and B to be α times, αk _G ^γG times,
αk _B ^γB times the analog amplifier 514−
All of R, 514-G and 514-B must be under the control of the CPU 515. FIG. 7 shows a circuit configuration of a third embodiment of the present invention. In this figure, 101 to 109 and 111 to 113 are the same as those in FIG. 710-R, 710-G, and 710-B are logarithmic conversion table RAMs (random access memories), respectively.
This is a memory that can be rewritten by the CPU 714. 71
Reference numeral 5 denotes a logarithmic table (LOG table) that is referred to by the CPU 714 to create a logarithmic conversion table for the RAMs 710-R, 710-G, and 710-B. 716 is the switching signal 11 in FIG.
A switching signal 717 is a film type designation signal for designating the type (characteristic) of the color negative film 104 used for reading. In the present embodiment, the orange base film is not used when the shading correction data is taken in. In the shading correction, the light amount unevenness of the illumination light source 101 and the CCD (line sensor) 10 are used.
It is configured to correct only the sensitivity unevenness of 6. That is, the R, G, and B outputs in a state where nothing is put in the film position 104 are stored in the shading RAM 108 for one line. In this case, the normalized signal N _R, N _G, from N _B (2),
In order to obtain the density signals D _R , D _G , and D _B equal to the expressions (3) and (4), a _R , a _G , and a _B are set as certain constants. What is necessary is to perform the conversion. a _R , a _G , and a _B are constants depending on the type of film (manufacturer, characteristics such as sensitivity), and can be set in advance. And (11),
Using equations (12) and (13), correction equations (5), (6),
(7) holds as it is. Therefore, when a color correction switching signal 716 corresponding to the color temperature of the illumination light source similar to the switching signal 114 of FIG. 1 is input and a film type designation signal 717 is input, the CPU 714 determines the k designated by the color correction switching signal 716. _G, and k _B value, a _R designated by the film type specification signal 717, a _G, from a _B value (11), (12), (13), and (5), (6), (7 ) Is performed, and the calculation result is used as a logarithmic conversion table, as a logarithmic conversion table RAM710-R,
Set to 710-G and 710-B. In the above calculation of the CPU 714, the logarithmic function in the arithmetic expression may be calculated with reference to the logarithmic table 715. Thereafter, the image portion of the film 104 is scanned, the shading corrected normalized signal N _R shading correction circuit 109, N _G, N _B is the logarithmic conversion table RAM710-R, 710-G, 710-B by the object density signal D _R ′,
The signals are converted into D _G ′ and D _B ′ and input to the UCR processing circuit 111. In each of the above embodiments, an in-line type image sensor (CCD) is used as the R, G, B film reading sensor. However, the present invention is not limited to this. For example, an area sensor, a 3P prism type color separation sensor or Any type of sensor may be used as long as it can read the film image in three colors, such as a laser scanner of three primary colors. If the logarithmic conversion table described above is of an exponential function type, it can be applied to an output signal to a color CRT (cathode ray tube). In addition to the color correction of the illumination light source described in the present embodiment, the k _G and k _B values can be determined in advance for other factors such as the fading of the film and the discoloration due to the development conditions. The present invention can be applied, and the effect of stabilizing the color correction work, that is, the effect of improving the operability is very large. [Effects of the Invention] As described above, according to the present invention, it is possible to perform color correction according to shooting conditions without requiring the skill of an operator, and to perform color correction of a color negative film shot under certain shooting conditions. The balance can be properly corrected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a circuit configuration of a first embodiment of the present invention, FIG. 2 is a diagram showing gradation characteristics of a color negative film, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a diagram showing an example of the relationship between input and output signals of a look-up table for converting a standardized signal into a density signal. FIG. FIG. 5 is a plan view showing an example of color correction switching means. FIG. 6 is a block diagram showing a circuit configuration of a second embodiment of the present invention. FIG. 7 is a third embodiment of the present invention. FIG. 3 is a block diagram illustrating an example circuit configuration. 101 …… Film illumination light source, 102 …… Condenser lens, 103…
... Cyan filter, 104 ... Color negative film, 105 ...
... imaging lens, 106 ... CCD (image sensor), 107 ...
... A / D converter, 108 ... Shading RAM, 109 ... Shading correction circuit, 110 ... Logarithmic conversion table ROM (lookup table), 111 ... UCR processing circuit, 112 ...
Masking circuit, 113 printer, 114, 516, 716 color correction switching signal (address switching signal), 514
Analog amplifier, 515, 714 CPU CPU 710 Log conversion table RAM 715 Log table 717 Film type designation signal.

Claims (1)

(57) [Claims] Input means for inputting color image data obtained by reading a negative film photographed under certain photographing conditions; storage means for storing a plurality of color correction data corresponding to the photographing conditions; Determining means for determining the certain photographing condition based on the color image data obtained; selecting means for selecting desired color correction data from the stored in the storage means based on the determined photographing condition; and the selecting means A color correction means for performing the desired color correction on the color image data input by the input means using the color correction data selected by the color negative film reading apparatus.