JPH0369280A - Reader for color photographic film image - Google Patents

Abstract

PURPOSE:To automatically obtain a color image signal with loyal gradation by deciding an exposure condition in photographing for the image signal of each color obtained by a preliminary image reading operation by using the gradation characteristic data of a color photographic film, and setting gradation conversion characteristic. CONSTITUTION:When the preliminary image reading operation is performed, the movable contact (v) of a switch SW is switched to the fixed contact (a) side with a switching control signal sent from a control circuit 13, and the operation of a gradation characteristic conversion circuit 10 is disabled. The control circuit 13 decides the exposure condition in the photographing of a recorded color photographic film 4 by using the digital image signal of each color stored in an image memory 12 and the gradation characteristic data of a film sent from a gradation characteristic data circuit 14 for film, and finds first gradation conversion characteristic and color correction characteristic, and sets them on the gradation characteristic convarsion circuit 10. When a regular image reading operation is performed, the gradation characteristic is converted and outputted with the first gradation conversion characteristic at the gradation characteristic conversion circuit 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for reading color photographic film images.

(Prior Art) Various types of color photographic film image reading devices have been proposed in the past, which photoelectrically convert a color photographic film image using a photoelectric conversion element such as a CCD image sensor to generate image signals of each color. .

By the way, as is well known, with color photographic film, if the exposure conditions at the time of shooting are different, even if the same subject is photographed, the resulting color images will have different gradations and color reproducibility. Conventionally, film image reading devices have been able to read color images from color photographic film taken under proper exposure conditions, even when reading color images from color photographic film whose exposure conditions were not appropriate at the time of shooting. Various proposals have been made to automatically obtain a color image signal similar to that obtained when a color photographic film is used. We are proposing an image reading device (Japanese Unexamined Patent Application Publication No. 63-2
(See Publication No. 0273).

The color photographic film image reading device shown in FIG.
For each color image signal obtained by a preliminary image reading operation on a recorded color photographic film whose exposure conditions at the time of photographing are unknown, the exposure conditions at the time of photographing are determined using the gradation characteristic data of the color photographic film. The gradation conversion characteristics are set based on the determined exposure conditions and the gradation characteristic data of the color photographic film, and after the preliminary image reading operation is performed on the recorded color photographic film. The apparatus includes means for obtaining image signals of each color whose tone characteristics are corrected using the tenth tone conversion characteristic described above for the image signals of each color obtained by the image reading operation performed, In FIG. 2, 1 is a light source, 2 is a lens, 3 is a holder for color photographic film 4, and 5 is an aperture.

6 is an imaging lens, 7 is a photoelectric conversion element such as a COD line image sensor, 8 is an analog-to-digital converter (AD converter...ADC), 9 is a digital clamp circuit, and 10 is a gradation characteristic conversion circuit. , 1 is a matrix circuit, 12 is an image memory, 13 is a control circuit, and 14 is a film gradation characteristic data circuit.

In the above-mentioned color photographic film image reading device shown in the second figure, when the light emitted from the light source 1 is projected onto the color photographic film held in the holder 4 through the lens 2, the light is used to read the color photographic film. Transmits through film 4,
Next, after passing through the aperture 5, the CO2 is collected by the imaging lens 6.
An image is formed on the D-line image sensor 7.

The above-described COD line image sensor 7 performs main scanning by itself and is moved in the sub-scanning direction to output three primary color signals Sr, Sg, and Sb corresponding to the color image on the color photographic film 4.

three primary color signals Sr corresponding to the color image of the color photographic film 4 output from the COD line image sensor 7;
Sg and Sb are analog/digital converters (AD converters/
... ADc) 8 converts it into a digital image signal and then gives it to the digital clamp circuit 9. After setting the black level in this digital clamp circuit 9, it supplies it to the Nll characteristic conversion circuit 10 and the image memory 12. Ru.

When the color photographic film image reading device performs a preliminary image reading operation on a recorded color photographic film whose exposure conditions at the time of photographing are unknown, the color photographic film image reading device reads the color image stored in the image memory 12 as described above. data, that is, digital image signals of 3M color signals Sr, Sg, and Sb corresponding to the color image of the recorded color photographic film 4, and the gradation characteristic data of the film sent from the gradation characteristic data circuit 14 of the film. The control circuit 13 determines the exposure conditions at the time of photographing the recorded color photographic film 4, and based on the determination result of the exposure conditions and the gradation characteristic data of the film, the control circuit 13 determines the recorded color photographic film 4. Three primary color signals Sr and Sg corresponding to the color image on the color photographic film 4.

The tone conversion characteristics and color correction characteristics to be applied to the sb digital image signal are determined, and the above-mentioned RLL tone conversion characteristics are set in the tone characteristic conversion circuit 10, and the above-mentioned color correction characteristics are set in the matrix circuit. Set to 11. Further, the control circuit 4 sets the aperture 5 to an aperture value according to the exposure conditions.

Next, when a formal image reading operation is performed on the recorded color photographic film whose exposure conditions at the time of photographing are unknown in the color photographic film image reading device, the color photograph output from the COD line image sensor 7 is read. Three primary color signals Slr and Sg corresponding to the color image of the film 4.

After sb is converted into a digital image signal by the analog-to-digital converter 8, the digital image signal of each color is supplied to the gradation characteristic conversion circuit 10 via the digital clamp circuit 9. After the tone characteristics are corrected, color correction is performed in the matrix circuit 11, so that the matrix circuit 11 can output each color signal that can reproduce a color image having appropriate gradations and colors.

(Problem to be Solved by the Invention) In the color photographic film image reading device shown in the second figure described above, even when reading a color image of a color photographic film whose exposure conditions were not appropriate at the time of photographing, it is possible to read a color image under appropriate exposure conditions. A color image signal with faithful gradation is automatically obtained in the same way as when reading a color image of color photographic film taken with The problem of not being able to obtain desirable gradation reproduction became a problem, and a solution to this problem was sought.

<Means for Solving Problem a) The present invention provides image signals of each color obtained by a preliminary image reading operation on a recorded color photographic film whose exposure conditions at the time of photographing are unknown. means for determining exposure conditions at the time of photographing using the characteristic data, and setting a first tone conversion characteristic based on the determined exposure conditions and the tone characteristic data of the color photographic film; The tone characteristics of the image signals of each color obtained by the image reading operation performed on the recorded color photographic film after the image reading operation described above are corrected using the first tone conversion characteristic described above. means for obtaining an image signal of each color; and determining the frequency distribution of the luminance component of the image signal whose gradation characteristics have been corrected by the above-described first gradation conversion characteristic, and performing the gradation conversion described above so as to flatten the frequency distribution. means for changing the characteristics to obtain a second gradation conversion characteristic;
The present invention provides a color photographic film image reading device comprising means for obtaining image signals of each color whose gradation characteristics are corrected by the above-mentioned second gradation conversion characteristics.

(Function) A preliminary image reading operation is performed on a recorded color photographic film whose exposure conditions at the time of photographing are unknown, and the gradation characteristic data regarding the color photographic film described above is used for the image signals of each color obtained thereby. to determine the exposure conditions during shooting.

A first gradation conversion characteristic is set based on the determined exposure condition and the gradation characteristic data of the color photographic film described above.

After the preliminary image reading operation described above, an image reading operation is performed on the recorded color photographic film, and the image signals of each color obtained thereby are subjected to the first image reading operation described above.
An image signal of each color whose gradation characteristics have been corrected is obtained using the gradation conversion characteristics of .

The frequency distribution of the luminance component of the image signal whose gradation characteristics have been corrected by the first wI tone conversion characteristic described above is determined, and the frequency distribution of the luminance component of the image signal is changed so as to be flattened.
Obtain the gradation conversion characteristics of

Image signals of each color whose gradation characteristics have been corrected by the above-described second gradation conversion characteristics are obtained and output.

(Example) Hereinafter, specific contents of the color photographic film image reading device of the present invention will be explained in detail with reference to the attached pages. FIG. 1 is a block diagram of an embodiment of the color photographic film image reading device of the present invention. In FIG. 1, 1 is a light source, 2 is a lens, 3 is a holder for color photographic film 4, 5 is an aperture, 6 is an imaging lens, 7 is a photoelectric conversion element such as a CCD line image sensor, 8 is an analog-to-digital converter (AD converter...ADC), 9 is a digital clamp circuit, and 10 is a gradation characteristic conversion circuit. .

11 is a matrix circuit, 12 is an image memory, 13 is a control circuit, 14 is a film gradation characteristic data circuit, and SW is a switch.

In the color photographic film image reading apparatus of the present invention shown in FIG. After passing through the photographic film 4 and then passing through the diaphragm 5, the C
An image is formed on the CD line image sensor 7.

The above-described CCD line image sensor 7 performs main scanning by itself and is moved in the sub-scanning direction to output three primary color signals Sr, Sg, and Sb corresponding to the color image on the color photographic film 4.

three primary color signals Sr corresponding to the color image of the color photographic film 4 output from the COD line image sensor 7;
Sg and Sb are converted into digital image signals by an analog-to-digital converter 8 and then supplied to a digital clamp circuit 9, and after the black level is set in this digital clamp circuit 9, they are sent to a gradation characteristic conversion circuit 10 and a switch. It is supplied to the fixed contact a in front of S.

First, when the color photographic film image reading device is performing a preliminary image reading operation on a recorded color photographic film whose exposure conditions at the time of photographing are unknown, the switching control signal sent from the control circuit 13 causes the switch to be switched. S
Because the previous movable contact V is switched to the fixed contact A side,
The digital image signals of each color sent out from the digital clamp circuit 9 are applied to the image memory 12 via the fixed contact a and the movable contact V in front of the switch S, and are stored in the image memory 12. Further, in the above state, the gradation characteristic conversion circuit 10 is inoperative.

The control circuit 13 receives the digital image signals (digital data) of each color stored in the image memory 12 as described above, that is, the three primary color signals Sr and Sg corresponding to the color image of the recorded color photographic film 4.

sb digital image signal and the film gradation characteristic data sent from the film gradation characteristic data circuit 14 of the film gradation characteristic data circuit 14, when the recorded color photographic film 4 is photographed. Determine the exposure conditions.

Based on the above-mentioned exposure condition determination result and the above-described film gradation characteristic data, three primary color signals Sr, S corresponding to the color image of the above-mentioned recorded color photographic film 4 are determined.
Determine the first gradation conversion characteristic and color correction characteristic to be applied to the digital image signals of g and Sb, and set the above-mentioned first gradation conversion characteristic in the gradation characteristic conversion circuit 10, The color correction characteristics described above are set in the matrix circuit 11. Further, the control circuit 4 sets the aperture 5 to an aperture value corresponding to one exposure condition.

Assuming that the input of the gradation characteristic conversion circuit 10 described above is also Y, and the output of the gradation characteristic conversion circuit 10 described above is Y, the first gradation conversion characteristic of the gradation characteristic conversion circuit 10 described above is Approximately expressed using an interval, the following equation (1) is obtained.

Y= aij(X-Xij)+Y (Xij≦X≦
""Lj) - (1) (where i=1 to n, j=R
, G, B, aij are coefficients) FIG. 3 shows an example of the first gradation conversion characteristic to be applied to a digital image signal of one color.

Next, in the color photographic film image reading device, when a formal image reading operation is performed on a recorded color photographic film whose exposure conditions at the time of photographing are unknown, the switching control signal sent from the control circuit 13 Since the movable contact V in front of the switch S is switched to the fixed contact side, the digital image signals of each color sent from the digital clamp circuit 9 described above are given to the gradation characteristic conversion circuit 1O, and the gradation characteristic conversion circuit In step 10, the gradation characteristics are converted using the first gradation conversion characteristics described above and are output.

As described above, the digital image signals of each color whose tone characteristics have been converted by the first tone conversion characteristic in the tone characteristic conversion circuit 10 are sent to the image memory via the fixed contact and the movable contact V in front of the switch S. 12 and stored in the image memory 12.

The above-mentioned control circuit 13 reads out the digital image signals of each color stored in the image memory 12, that is, the image signals of each color whose gradation characteristics have been corrected according to the above-described first gradation conversion characteristics, and Find the frequency distribution of the luminance component of the image signal whose gradation characteristics have been corrected using the gradation conversion characteristics of A second gradation conversion characteristic that provides the following is determined and set in the gradation characteristic conversion circuit 10. Note that the green signal may be used instead of the luminance component of the image signal as the signal used when determining the second gradation conversion characteristic described above.

The above-mentioned second gradation conversion characteristic is expressed by the above-mentioned equation (1) Yi
By converting j as in equation (2), it is expressed as in equation (3).

Yij YmaxΣD (k) k=0 Y1 month=α□+(1-α)Yij...(2)Y
= a'1j (X-Xij) + Y'ij (X
ij≦X5Xi+1. j) −(3) However, Ymax
is the maximum output value, and N is the total number of pixels.

α is a coefficient that adjusts the fidelity of tone reproduction, and 0≦α
It is determined within the range of ≦1. Further, a'ij is a coefficient, and D (k) is a frequency distribution of the luminance component.

Next, in the control circuit 13, the switching control signal switches the movable contact V in front of the switch S from the fixed contact side to the fixed contact a side, and then converts the digital data of each color whose gradation characteristics have been converted by the first gradation conversion characteristic. The image signal is read from the image memory 12 and supplied to the gradation characteristic conversion circuit IO.

In the gradation characteristic conversion circuit 10, the digital image signals of each color supplied thereto are converted into digital image signals of each color whose gradation characteristics have been converted by the second gradation conversion characteristic, and are converted to the matrix circuit 1.
1, color correction is performed in the matrix circuit 11, and the matrix circuit 11 outputs each color signal capable of reproducing a color image having visually appropriate gradations and colors.

(Effects of the Invention) As is clear from the above detailed explanation, the color photographic film image reading device of the present invention provides a preliminary image for a recorded color photographic film whose exposure conditions at the time of photographing are unknown. A reading operation is performed, and for the image signals of each color obtained thereby, the exposure conditions at the time of shooting are determined using the gradation characteristic data regarding the color photographic film described above, and the exposure conditions determined as described above and the color photographic film described above are determined. The first gradation conversion characteristic is set based on the gradation characteristic data of Regarding the image signal, an image signal of each color is obtained whose gradation characteristics are corrected using the first gradation conversion characteristic described above, and the gradation characteristics are corrected using the first gradation conversion characteristic described above. Obtain the frequency distribution of the luminance component of the image signal, change the above-mentioned gradation conversion characteristic so as to flatten it, obtain the second gradation conversion characteristic, and convert the gradation using the above-described second gradation conversion characteristic. Since it is designed to obtain and output image signals for each color with corrected tonality characteristics, even if a color image is read from color photographic film whose exposure conditions were not appropriate at the time of shooting, it will still be possible to obtain and output the image signals under appropriate exposure conditions. Not only can a color image signal with the same faithful gradation as when reading a color image from a color photographic film in the state in which it was taken automatically be obtained, but also a visually pleasing gradation reproduction can be obtained. According to the present invention, the above-mentioned conventional problems can be satisfactorily solved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the color photographic film image reading device of the present invention, FIG. 2 is a block diagram of a conventional color photographic film image reading device, and FIG. 3 is a characteristic side view for explanation. be. DESCRIPTION OF SYMBOLS 1... Light source, 2... Lens, 3... Holder for color photographic film 4, 5... Aperture, 6... Imaging lens, 7... Photoelectric conversion element, 8... Analog - Digital converter, 9... Digital clamp circuit, 1o... Gradation characteristic conversion circuit, 11... Matrix circuit, 12...
- Image memory, 13... Control circuit, 14... Film gradation characteristic data circuit, SW... Switch.

Claims (1)

[Claims] For each color image signal obtained by a preliminary image reading operation on a recorded color photographic film whose exposure conditions at the time of photographing are unknown, the exposure conditions at the time of photographing are determined using the gradation characteristic data of the color photographic film. , means for setting a first gradation conversion characteristic based on the determined exposure condition and the gradation characteristic data of the color photographic film; and after the preliminary image reading operation, the recorded color photograph is read. means for obtaining image signals of each color whose gradation characteristics have been corrected using the above-described first gradation conversion characteristics with respect to image signals of each color obtained by an image reading operation performed on the film; Find the frequency distribution of the luminance component of the image signal whose gradation characteristics have been corrected by the gradation conversion characteristics of and means for obtaining image signals of each color whose gradation characteristics have been corrected by the second gradation conversion characteristics described above.