JPH0583559A - Image reader - Google Patents

Abstract

PURPOSE:To improve color reproducibility to a negative film and to improve efficiency for utilizing optical energy. CONSTITUTION:A luminance signal Y of an image on a color film 1 and color difference signals SDR and SDB are obtained by a color separation filter 3, line sensor 11, memories 15R-15B and matrix circuit 18 or the like. When the color film 1 is a reversal film, the luminance signal Y and the color difference signals SDR and SDB are obtained with the matrix circuit 18 as a first matrix characteristic. When the color film 1 is the negative film, the luminance signal Y and the color difference signals SDR and SDB are obtained with the matrix circuit 18 as a second matrix characteristic, one part of a red component is added to a green component concerning the luminance signal Y and the color difference signals SDR and SDB, and one part of the green component is subtracted from the red component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading an image on a color film and outputting a video signal.

[0002]

2. Description of the Related Art As an image reading apparatus, there is a film scanner which reads an image (frame) on a color film and outputs image data such as a video signal.

In this film scanner, generally, a target image is picked up by a line sensor at an appropriate scanning speed, the picked-up image signal is temporarily stored in a frame memory, and the stored signal is read at a predetermined synchronous speed. For example, an NTSC video signal is obtained.

[0004]

By the way, color films include reversal films and negative films. In general, the spectral density characteristic of the reversal film is shown as a solid line in FIG. 3, and the spectral density characteristic of the negative film is shown as a broken line in FIG. That is,
The wavelength distribution of the cyan dye is different between the reversal film and the negative film, and the wavelength distribution of the cyan dye of the negative film is shifted to a longer wavelength side than the wavelength distribution of the cyan dye of the reversal film.

Therefore, when a negative film image is read in a film scanner for a general color film, a red filter of a color separation filter having a cutoff wavelength shifted to a long wavelength side is used.

However, when the red filter whose cut-off wavelength is shifted to the long wavelength side is used, the utilization efficiency of light energy is lowered. In particular, when a fluorescent lamp is used as the light source, since the fluorescent lamp has a small number of long-wavelength components, it is necessary to lengthen the charge accumulation time of the image capturing line sensor, which results in a long reading time.

However, if reading is performed without shifting the cut-off wavelength of the red filter to the long wavelength side, the green signal adjacent to red is often included in the red signal, resulting in poor color reproducibility. turn into.

The present invention is intended to solve such a problem.

[0009]

For this reason, in the present invention, when the reference numerals of the respective parts correspond to the embodiments described later, the color film 1 to be read is either a reversal film or a negative film. And the first to third color filters R to B having different color separation characteristics for the reversal film and the image on the color film 1 to the first to third color filters R to B.
Through the line sensor 11 which is imaged through the line sensor 11 and scans the color film 1 relative to the color film 1.
A / D converter 14 for A / D converting to 14 and digital signals R14-B14 for the first to third color filters R-B
1st to 3rd memories 15R which store corresponding to the case of
.About.15B and first to third D / A for converting the digital signals R14 to B14 stored in the first to third memories 15R to 15B into simultaneous analog signals R15 to B15, respectively.
Converters 17R to 17B and analog signals R15 to B15
And a matrix circuit 18 that matrixes with the first or second characteristics. And color film 1
However, in the case of a reversal film, the matrix circuit 18 uses the analog signal R as the first matrix characteristic.
The luminance signal Y and the color difference signals SDR and SDB or the three primary color signals ROT to BOT are taken out from 15 to B15, and when the color film 1 is a negative film, the matrix circuit 18
Is the analog signal R15-
The luminance signal Y and the color difference signals SDR and SDB, or the three primary color signals ROT to BOT are extracted from B15, and the luminance signal Y
And the color difference signals SDR and SDB, part of the red component is added to the green component, and part of the green component is subtracted from the red component.

[0010]

When the negative film is read, the color reproducibility for the negative film is improved without shifting the cutoff wavelength of the color filter R to the long wavelength side.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a color film from which an image can be read, which is, for example, a 35 mm reversal film or a negative film. Further, reference numeral 20 denotes a microcomputer (CPU system) that integrally controls the operation or processing of each part of this apparatus.

Then, the white light from the light source 2 is applied to the film 1 through the color separation filter 3, and the image of the film 1 is formed on the line sensor 11 by the lens 4. In this case, the film 1 is configured to move at a predetermined speed in the sub-scanning direction (horizontal direction) by the drive motor 21 during image pickup. Further, as the light source 2, a three-wavelength fluorescent lamp or a halogen lamp can be used.

Further, the color separation filter 3 has a filter section R for transmitting red light, a filter section G for transmitting green light, and a filter section B for transmitting blue light, and these filter sections R to B are provided. Is a spectral density characteristic adapted to a reversal film. The filter 3 is rotated by the drive motor 23 so that the filter portions RB are sequentially positioned on the optical path between the light source 2 and the film 1. The motor 21,
The rotation of 23 is controlled by the microcomputer 20.

Further, in this example, the line sensor 11 is a CCD line sensor having a VOFD (vertical overflow drain) structure, and the line sensor 11 of the lens 4 is arranged so that its scanning direction is the main scanning direction (vertical direction). It is provided at the image forming position, and the main scanning read clock is supplied from the microcomputer 20.

Further, 12 is a gain control amplifier, 13 is a gamma correction amplifier, 14 is an 8-bit A / D converter, and 15R to 15B are frame memories. In this case, the gamma correction amplifier 13 has a first correction characteristic for performing the gamma correction when the film 1 is a reversal film and a second correction characteristic for performing the gamma correction when the film 1 is a negative film. Then, these correction characteristics are selected by the control signal from the microcomputer 20.

Further, 16R to 16B are lookup tables, 17R to 17B are D / A converters, and 18 is a matrix circuit. In this case, the look-up tables 16R to 16B are the first data table that outputs the color signals as they are when the film 1 is a reversal film, and the negative / positive conversion for the color signals when the film 1 is a negative film ( A second data table for performing color reversal), and these data tables are selected by the microcomputer 20. Furthermore, the matrix circuit 1
8 is configured as shown in FIG. 2, for example, and its switch circuit 85 is switched by the microcomputer 20 depending on whether the film 1 is a reversal film or a negative film.

Then, the reading of the film 1 is performed as follows. When the film 1 is a reversal film: The microcomputer 20 sets the gamma correction circuit 13 and the look-up tables 16R to 16B to have characteristics for the reversal film, and the switch circuit 85 is connected to the state shown in FIG. Further, the motor 23 is controlled by the microcomputer 20, and the red color filter section R of the color separation filter 3 is controlled.
Are located on the optical path between the light source 2 and the film 1. Then, the motor 21 is controlled by the microcomputer 20, the film 1 is transferred in the sub-scanning direction at a predetermined speed for the target frame, and the microcomputer 20 supplies a read clock to the line sensor 11.

Therefore, the image signal S11 of the red component of the target frame of the film 1 is taken out from the line sensor 11 at a speed corresponding to the moving speed of the film 1 and the frequency of the read clock.

The red component signal S11 is supplied to the A / D converter 14 through the amplifier 12 and the gamma correction amplifier 13 and A / D converted into the digital red signal R14, and the signal R14 is sequentially supplied to the frame memory 15R. Written. The write address at this time is an address corresponding to the scanning position of the line sensor 11.

In this way, the target frame of the film 1 is imaged by the line sensor 11, and the red signal R14 for one frame is stored in the frame memory 15R.

Next, the motor 23 drives the color separation filter 3
The green filter part G is located on the optical path between the light source 2 and the film 1, and the film 21 is transferred by the motor 21 at the predetermined speed in the sub-scanning direction to the target frame.

Therefore, the line sensor 11 takes out the image pickup signal S11 of the green component of the target frame of the film 1, this signal S11 is A / D converted into the digital green signal G14 by the A / D converter 14, and this Signal G14
Are sequentially written in the frame memory 15G. Thus, the green signal G14 for one frame of the target frame of the film 1 is stored in the frame memory 15G.

Subsequently, the motor 23 positions the blue filter portion B of the color separation filter 3 on the optical path between the light source 2 and the film 1, and the motor 21 sets the film 1 at a predetermined target frame. It is transported in the sub-scanning direction at the speed of.

Therefore, the line sensor 11 takes out the image pickup signal S11 of the blue component of the target frame of the film 1, this signal S11 is A / D converted into the digital blue signal B14 by the A / D converter 14, and this Signal B14
Are sequentially written in the frame memory 15B. In this way, the blue signal B14 for one frame of the target frame of the film 1 is stored in the frame memory 15B.

Thus, the target frame of the film 1 is
The color separation filter 3 and the line sensor 11 image the images sequentially, and the digital color signals R14 to B14 thereof are stored in the frame memories 15R to 15B, respectively.

Then, the signal R14 of the memories 15R to 15B.
.About.B14 are read out repeatedly so that the corresponding pixels become the same, so that digital color signals R15 to B15 at the synchronous speed in the NTSC system are taken out, and these signals R15 to B15 are looked up at the lookup tables 16R to 16.
It is supplied to the D / A converters 17R to 17B through B and D / A converted into the analog color signals R15 to B15, and the signals R15 to B15 are supplied to the matrix circuit 18.

In the matrix circuit 18, the signals R15 to B15 are added to the adder circuit 8 as shown in FIG.
A luminance signal Y81 represented by Y81 = 0.3 R15 + 0.59G15 + 0.11B15 is formed by being supplied to 1 and this signal Y81 is taken out to the terminal 19Y as a luminance signal through the switch circuit 85.

Further, the signal R15 from the D / A converter 17R is supplied to the adding circuit 83, and at the same time, the adding circuit 8
The signal Y81 from 1 is supplied to the inverting circuit 82 to be a phase-inverted signal -Y81, and this signal -Y81 is added by the adding circuit 83.
To the signal (R15-Y81) from the adder circuit 83.
Is taken out. And this signal (R15-Y81)
It is supplied to the amplifier 84 and multiplied by 1.15 to make SDR = 1.15 (R15-Y81), and this signal SDR is the terminal 19R as a red color difference signal.
Taken out.

Further, the signal Y81 from the adder circuit 81 is supplied to the inverting circuit 87 through the switch circuit 85 to be a phase-inverted signal -Y81, and this signal -Y81 is supplied to the adder circuit 88 and D / A. The signal B15 from the converter 17B is supplied to the adding circuit 88,
A signal (B15-Y81) is taken out from. And
This signal (B15-Y81) is supplied to the amplifier 89.
It is multiplied by 15 to make SDB = 1.15 (B15-Y81), and this signal SDB is the color difference signal of blue at the terminal 19B.
Taken out.

Thus, in the present case, the terminals 19Y to 19B are
, The luminance signal Y when reading the reversal film
81 and the color difference signals SDR and SDB are taken out. When the film 1 is a negative film: The microcomputer 20 sets the gamma correction circuit 13 and the look-up tables 16R to 16B to have characteristics for a negative film, and the switch circuit 85 is connected in a state opposite to that shown in the drawing. Then, the color separation filter 3 and the film 1 are controlled in the same manner as in the case, and the target frame of the film 1 is the color separation filter 3 and the line sensor 11.
The image is sequentially captured by the digital color signals R14 to B
14 are stored in the frame memories 15R to 15B, respectively.

Then, the signal R14 of the memories 15R to 15B.
.. to B14 are repeatedly read out in a predetermined order to extract digital color signals R15 to B15 at the synchronous speed in the NTSC system, and these signals R15 to B15 are passed through the look-up tables 16R to 16B to the D / A converters 17R to 17B. Is supplied to the analog color signal R15
.About.B15 are D / A converted, and the signals R15 to B15 are supplied to the matrix circuit 18.

In the matrix circuit 18, the signals R15 to B15 are supplied to the adder circuit 86 to form a luminance signal Y86 represented by Y86 = 0.4 R15 + 0.49 G15 + 0.11B15, and this signal Y86 is transmitted through the switch circuit 85 to the luminance. The signal is taken out to the terminal 19Y.

Further, the signal SDR from the amplifier 84 is taken out to the terminal 19R as a red color difference signal.

Further, the signal Y86 from the adder circuit 86 is supplied to the inversion circuit 87 through the switch circuit 85 to be a phase-inverted signal -Y86, which is supplied to the adder circuit 88 and D / A. The signal B15 from the converter 17B is supplied to the adding circuit 88,
The signal (B15-Y86) is taken out from. And
This signal (B15-Y86) is supplied to the amplifier 89.
It is multiplied by 15 to make SDB = 1.15 (B15-Y86), and this signal SDB is the terminal 19B as the blue color difference signal.
Taken out.

Thus, in the present case, the terminals 19Y to 19B are provided.
Then, the luminance signal Y86 and the color difference signals SDR and SDB when the negative film is read are extracted.

As described above, the terminals 19Y to 19B are provided.
First, the luminance signal Y (Y is Y81 or Y86) and the color difference signals SDR and SDB when the reversal film or the negative film is read are extracted.

In this case, these signals Y, SDR,
Although not shown, SDB is matrixed in a matrix circuit or a CRT monitor in the subsequent stage and converted into three primary color signals ROT, GOT, BOT, and when film 1 is a reversal film, ROT = 1.11R15-0.09G15-0.02B15 GOT = -0.05R15 + 1.06G15-0.02B15 BOT = -0.05R15-0.09G15 + 1.13B15.

When the film 1 is a negative film, ROT = 1.2 R15-0.19G15-0.02B15 GOT = 0.07R15 + 0.93G15-0.02B15 BOT = -0.06R15-0.07G15 + 1.13B15.

That is, when the film 1 is a reversal film, the normal matrix processing is performed, but when the film 1 is a negative film, a part of the red component is added to the green component, and a part of the green component is added to the red component. Is subtracted from.

Therefore, when reading a negative film,
It is possible to obtain the luminance signal Y and the color difference signals SDR and SDB of appropriate hues without shifting the cutoff wavelength of the red filter portion R of the color separation filter 3 to the long wavelength side. That is, the color reproducibility can be improved without lowering the utilization efficiency of light energy.

In the above description, when a fluorescent lamp is used as the light source 2, a heater for keeping the lamp warm can be attached to prevent a decrease in brightness at low temperatures. In addition, an infrared cut filter may be arranged on the optical path between the light source 2 and the line sensor 11 in order to prevent the influence of infrared rays from the light source 2 or the heater for keeping the temperature thereof. Further, the line sensor 11 may be a color line sensor.

Further, in the above description, the target frame of the film 1 is imaged in the frame-sequential manner by the color separation filter 3 and the line sensor 11, but it may be imaged in the line-sequential manner.

[0043]

According to the present invention, when the film 1 is a reversal film, a normal matrix treatment is carried out, but when the film 1 is a negative film, a part of the red component is added to the green component and the green component is added. Since the process of subtracting a part of the red component from the red component is performed, it is not necessary to shift the cutoff wavelength of the red filter portion R of the color separation filter 3 to the long wavelength side when the film 1 is a negative film. Therefore, color reproducibility can be improved without lowering the utilization efficiency of light energy.

Moreover, the masking process is performed by the matrix circuit 18 at the stage subsequent to the D / A converters 17R to 17B.
Since it is realized by analog processing in, the matrix circuit 18 for that has a very simple structure,
It is low cost.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of the present invention.

FIG. 2 is a system diagram showing an example of a matrix circuit.

FIG. 3 is a diagram showing a spectral density characteristic of a film.

[Explanation of symbols]

 1 Image to be read 2 Light source 3 Color separation filter 4 Lens 11 CCD line sensor 14 A / D converter 15R to 15B Frame memory 16R to 16B Look-up table 17R to 17B D / A converter 18 Matrix circuit 20 Microcomputer 81, 83, 86 , 88 Adder circuit 82, 87 Inverter circuit

Claims (1)

[Claims] 1. A color film to be read is
First to third color filters that are commonly used in the case of a reversal film and a negative film and have different color separation characteristics for the reversal film, and the image on the color film is the first A line sensor which is imaged through a third color filter and which scans relative to the color film, and an A / D converter which A / D converts an output signal of the line sensor into a digital signal This digital signal is stored in the first to third memories corresponding to the first to third color filters, and the digital signals stored in the first to third memories are simultaneously analogized. First to third to convert into signals respectively
D / A converter and a matrix circuit for matrixing the analog signal with the first or second characteristic. When the color film is the reversal film, the matrix circuit is provided with the first matrix characteristic. As the luminance signal and the color difference signal or the three primary color signals from the analog signal, the color film is the negative film,
The matrix circuit extracts the luminance signal and the color difference signal or the three primary color signals from the analog signal as the second matrix characteristic, and adds a part of the red component to the green component with respect to the luminance signal and the color difference signal. And an image reading apparatus that subtracts a part of the green color component from the red color component.