JP2001169052A - Device and method for processing image signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and also small image signal processor capable of generating an appropriate image signal with respect to various originals. SOLUTION: This image signal processor has a line sensor including photoelectric transducers in a one-dimensional array which generate a color image signal by continuously scanning an original and performing photoelectric conversion, a deciding means 6 for deciding the type of the original on the basis of the balance of the color image signal generated by the line sensor, a charge accumulation time controlling means 6 for controlling the charge accumulation time of the photoelectric transducers in each color in accordance with the type of the original, line buffers 7 and 9 for buffering image signals, and a balancing means 8 and 10 for performing balancing processing between lines about the image signal of a prescribed color on the basis of the image signal buffered in accordance with the type of the original and the image signal generated by the line sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image signal processing technique, and more particularly to a technique for processing an image signal generated by photoelectric conversion.

[0002]

2. Description of the Related Art An image scanner generates an image signal while relatively moving a document. When reading an image on a negative film or a positive film, light is applied to the negative film or the positive film, and an image signal is generated based on the transmitted light. The transmittance of each color component is different between the negative film and the positive film. It is difficult to properly read both negative and positive film images using the same light source.

Therefore, an image scanner has been proposed which is capable of reading both images of a negative film and a positive film by providing a light source for a negative film and a light source for a positive film, and switching between the light sources. . In some cases, the difference between the two is corrected using a glass filter.

[0004]

The provision of a dedicated light source or glass filter for negative or positive films increases the complexity and size of the image scanner.
An object of the present invention is to provide a simple and compact image signal processing apparatus and method capable of generating appropriate image signals for various originals.

[0005]

According to one aspect of the present invention, there is provided an image sensor including a photoelectric conversion element for generating an image signal by photoelectric conversion, and a charge storage time change for changing a charge storage time of the photoelectric conversion element. There is provided an image signal processing apparatus comprising: means; and a spatial frequency compensating means for compensating for a spatial frequency of an image signal generated by the photoelectric conversion element whose charge accumulation time has been changed.

According to another aspect of the present invention, there is provided a line sensor including a one-dimensional array of photoelectric conversion elements for generating a color image signal by continuously scanning a document and performing photoelectric conversion; Determining means for determining the type of the document based on the balance of the color image signals to be processed; charge storage time control means for controlling the charge storage time of the photoelectric conversion element for each color according to the type of the document; and the line sensor A line buffer for buffering the image signal generated by the line sensor, and an image signal of a predetermined color based on the buffered image signal and the image signal generated by the line sensor according to the type of the document. An image signal processing device having an averaging means for performing an averaging process is provided.

According to still another aspect of the present invention, there is provided an image signal processing apparatus including a one-dimensional array of photoelectric conversion elements for generating a color image signal by continuously scanning a document and performing photoelectric conversion. A method for determining the type of a document based on a balance of color image signals generated by the photoelectric conversion element; and (b) determining a type of the photoelectric conversion element for each color according to the type of the document. There is provided an image signal processing method including a step of controlling a charge accumulation time and a step of (c) performing an averaging process between lines for an image signal of a predetermined color according to the type of the document.

As described above, according to the present invention, the charge accumulation time for each color of the photoelectric conversion element is controlled in accordance with the type of the original,
By performing spatial frequency compensation (averaging between lines), white balance can be achieved regardless of the type of document, and an image signal with a high SN ratio can be obtained. Further, it is possible to provide a simple and small image signal processing device as compared with an image scanner or the like having two types of light sources. In addition, since the image signal is generated while the document is continuously moved (scanning), the image signal can be generated at a higher speed than when the document is moved stepwise.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration of an image signal processing device (image scanner) according to an embodiment of the present invention. A lamp (light source) 1 irradiates a movable original 2 with light. The original 2 is, for example, a negative film or a positive film, and is a transparent original that transmits light from the lamp 1. The transmitted light is collected by the lens 3 and forms an image on the line sensor 4. Manuscript 2
The color component of the base layer of the film is different between the case of the negative film and the case of the positive film, so that the transmittance of each color component of the film is different. It is necessary to separately maintain white balance (gray balance) between a negative film and a positive film. As the lamp 1, either one of a negative film and a positive film having a spectral characteristic capable of achieving a white balance is selected. For example, the lamp 1 uses a negative film capable of achieving white balance. The negative film lamp 1 has, for example, an emission spectrum having three sharp peaks corresponding to red (R), green (G), and blue (B) wavelength bands, and a color filter of a CCD used. It has B-rich characteristics such that white balance can be obtained by combining spectral characteristics and a negative base. That is, it has not only a sharp peak in each of the RGB wavelength bands but also a peak value that cancels a negative base color. In other words, the lamp 1 does not necessarily need to have a sharp peak in each of the RGB wavelength bands, and (spectral characteristics of the lamp) × (spectral characteristics of the color filter of the CCD) × (spectral characteristics of the negative base) are flat and balanced. It is preferable to have good characteristics.

The line sensor (image sensor) 4 is
A sensor in which photoelectric conversion elements (photodiodes) for converting R, G, and B lights into electric signals are arranged one-dimensionally.
A charge coupled device (CCD) is provided in addition to the photoelectric conversion device.
R, G, and B color filters are arranged on the photoelectric conversion elements. The line sensor 4 can adjust the sensitivity of each color by controlling the charge accumulation time of the photoelectric conversion element of each color. The longer the charge storage time of a photoelectric conversion element of a certain color, the higher the sensitivity of that color and a larger image signal can be obtained. The line sensor 4 generates and outputs a one-line color image signal of the image on the document 2 by main scanning, and outputs the color image signal by sub-scanning for continuously moving the document 2.
Output a two-dimensional color image signal. The color image signal is
It consists of an R signal, a G signal and a B signal.

The signal processing section 5 determines whether the original 2 is a negative film or a positive film, performs image signal processing according to each film, and obtains a white balance. That is, it is automatically determined whether the original 2 is a negative film or a positive film, and a white balance can be obtained regardless of which film is used. C
The PU 6 controls the signal processing unit 5 and the line sensor 4 and inputs a color image signal with a white balance from the signal processing unit 5.

FIG. 2 is a block diagram showing a configuration of the signal processing unit 5 and the CPU 6. The signal processing unit 5 includes an amplifier 12
r, 12g, 12b, line buffers 7, 9 for buffering image signals, averaging circuits 8, 10 for averaging image signals between lines, and terminals 14a or 14b are selectively connected to output terminals. Switch 11a and terminal 15
switch 1 for selectively connecting a or 15b to the output terminal
1b, and a switch control unit 11. CPU 6
It has an analog / digital (A / D) converter 13.

Next, a specific processing procedure will be described. First, a method of determining whether the original 2 is a negative film or a positive film will be described. The CPU 6 sets the charge accumulation time of all the R, G, and B photoelectric conversion elements on the line sensor 4 to be equal. When the document 2 is inserted into the image scanner, light from the lamp 1 passes through the document 2 and is condensed on the line sensor 4 by the lens 3. The line sensor 4 performs a photoelectric conversion to generate a color image signal,
Output to the signal processing unit 5. The switch control unit 11 includes a CP
According to the instruction of U6, the switch 11a is connected to the terminal 14a, and the switch 11b is connected to the terminal 15a. An R signal, a G signal, and a B signal (hereinafter, referred to as RGB signals) are input to the signal processing unit 5 from the line sensor 4. Those RG
The B signal is amplified at a predetermined amplification rate by the amplifiers 12r, 12g, and 12b, and output to the CPU 6. CPU6
Receives the RGB signals at the boundary between the frames of the document (film) 2 and determines whether the document 2 is a negative film or a positive film based on the balance of the color image signals. For example, since the lamp 1 uses a negative film capable of achieving white balance, the CPU 6
If the white balance of the signal is substantially attained, it is determined that the original 2 is a negative film, and if the white balance is lost, it is determined that the original 2 is a positive film.

When the CPU 6 determines that the document 2 is a negative film, the CPU 6 keeps the charge accumulation time of the line sensor 4 as it is, and also keeps the switches 11a and 11b of the signal processing unit 5 as it is. That is, the line sensor 4 outputs R and G
The signal processing unit 5 sets the charge accumulation times of the photoelectric conversion elements of all colors B and B to be equal, and amplifies and outputs the RGB signals in a predetermined manner. This is because the lamp 1 has spectral characteristics for a negative film.

When the CPU 6 determines that the original 2 is a positive film, the CPU 6 controls the charge accumulation time of the G and B photoelectric conversion elements on the line sensor 4 to be halved. 11 has switches 11a and 11b
To switch. The switch 11a is connected to the terminal 14b
To the output terminal. The switch 11b is connected to the terminal 15b
To the output terminal. The R signal from the line sensor 4 is amplified by the amplifier 12r and output to the CPU 6.

The G signal from the line sensor 4 is supplied to the amplifier 1
The signal is amplified by 2 g and input to one of the + terminals of the line buffer 7 and the averaging circuit 8. The line buffer 7
The G signal delayed by one line is output to the other + terminal of the averaging circuit 8. The averaging circuit 8 averages the G signals of the current line and the previous line and outputs the result to the CPU 6.

The B signal from the line sensor 4 is supplied to the amplifier 1
The signal is amplified by 2b and input to one of the + terminals of the line buffer 9 and the averaging circuit 10. Line buffer 9
Outputs the B signal delayed by one line to the other + terminal of the averaging circuit 10. The averaging circuit 10 averages the B signals of the current line and the previous line and outputs the result to the CPU 6.

The base layer of a positive film has a higher transmittance at a short wavelength (B side) and a lower transmittance at a long wavelength (R side) as compared with the base layer of a negative film. In addition, the charge accumulation time of G and B is shortened to lower the sensitivity. Also, by averaging between lines to lower (compensate) the spatial frequency, noise can be removed and the SN ratio can be increased.

According to whether the original 2 is a negative film or a positive film, the line sensor 4 and the signal processing section 5 are set to the above-mentioned states, and the original 2 is moved (scanning).
Is continued. The line sensor 4 includes a document (film) 2
And generates and outputs an image signal corresponding to the image in the frame. The signal processing unit 5 outputs to the CPU 6 an RGB signal of the document 2 in which the white balance is obtained. The CPU 6 converts an analog RGB signal into a digital format by an internal A / D converter 13.

When another original 2 is inserted into the image scanner, it is again determined whether the original 2 is a negative film or a positive film, and the same processing as described above is performed. When determining the type of the document (film) 2,
The judgment is made based on the RGB signals at the boundary of the frame of the film. However, if the color of the base layer of the film appears, the judgment is made based on the RGB signals of other parts such as the end of the film. Is also good.

Although the case where the document 2 is moved has been described, the line sensor 4 may be moved since the document 2 and the line sensor 4 only need to move relatively. All 3 of RGB
In order to change the charge storage time of the color, the intensity of the lamp 1 and the scanning speed of the document 2 may be changed.

The lamp 1 is not limited to a lamp having spectral characteristics for a negative film, but may be a lamp having spectral characteristics for a positive film. When a lamp having a flat spectral characteristic for a positive film is used as the lamp 1, a process reverse to that of the present embodiment may be performed. That is, when it is determined that the document 2 is a negative film, the charge accumulation time for only the R signal may be shortened, and the line-to-line averaging process may be performed by the line buffer.

If a filter is arranged between the lamp 1 and the line sensor 4 to cancel the color of the base layer of the negative film, the above cancellation can be further enhanced.

According to the present embodiment, the charge accumulation time for each color of the line sensor is controlled in accordance with the type of film, and the averaging process between lines is performed, whereby the white balance can be adjusted regardless of the type of original. Can be taken. At this time, since the charge accumulation time is set and averaged for each color, an image signal with a high SN ratio can be obtained.

Further, in this embodiment, an image scanner which is simpler and smaller than an image scanner having two kinds of light sources can be provided, and the performance of each apparatus due to individual differences such as spectral characteristics of parts can be provided. Variation can be reduced. In addition, the manuscript is continuously moved (scanning)
Since the image signal is generated while the document is being moved, the image signal can be generated at a higher speed than when the document is moved stepwise.

The present invention also includes a software program code for realizing the functions of the above-described embodiment, which is implemented by operating according to a program stored in a computer (CPU or MPU) of the image scanner. included.

In this case, the program code itself of the software realizes the function of the above-described embodiment, and the program code itself and means for supplying the program code to the computer, for example, storing the program code The recorded recording medium constitutes the present invention. As a recording medium for storing such a program code, for example, a floppy disk, a hard disk,
An optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

It should be noted that each of the above-described embodiments is merely an example of the embodiment for carrying out the present invention, and the technical scope of the present invention should not be interpreted in a limited manner. It is. That is, the present invention does not depart from the spirit or the main features thereof,
It can be implemented in various forms.

[0029]

As described above, according to the present invention, the charge accumulation time for each color of the photoelectric conversion element is controlled in accordance with the type of the document, and the spatial frequency is compensated (average processing between lines). Thus, white balance can be obtained regardless of the type of the original, and an image signal with a high SN ratio can be obtained. Further, it is possible to provide a simple and small image signal processing device as compared with an image scanner or the like having two types of light sources. In addition, since the image signal is generated while the document is continuously moved (scanning), the image signal can be generated at a higher speed than when the document is moved stepwise.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image scanner according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a signal processing unit and a CPU according to the embodiment.

[Explanation of symbols]

 Reference Signs List 1 lamp 2 original 3 lens 4 line sensor 5 signal processing unit 6 CPU 7,9 buffer 8,10 averaging circuit 11 switch control unit 11a, 11b switch 12 amplifier 13 A / D converter 14,15 switch terminal

Continued on front page F term (reference) 5C072 AA01 BA19 EA05 FB19 QA10 QA17 QA20 RA01 UA12 UA20 VA03 5C077 LL19 MM03 MM12 MP08 PP31 PP32 PP43 PP46 PQ18 PQ24 5C079 HB01 JA01 JA23 LA01 LA23 MA03 MA11 NA03

Claims (15)

[Claims] 1. An image sensor including a photoelectric conversion element that generates an image signal by photoelectric conversion, a charge storage time changing unit that changes a charge storage time of the photoelectric conversion element, and a photoelectric conversion element that changes the charge storage time And a spatial frequency compensating means for compensating for a spatial frequency of the image signal generated by the image signal processing apparatus. 2. The image signal processing apparatus according to claim 1, wherein the image sensor is a line sensor in which photoelectric conversion elements that perform photoelectric conversion of a plurality of colors are arranged one-dimensionally. 3. The image signal processing device according to claim 1, wherein the image sensor further includes a CCD. 4. The image signal processing apparatus according to claim 1, wherein said spatial frequency compensation means performs an averaging process between lines of said image signal. 5. The image signal processing apparatus according to claim 4, wherein said spatial frequency compensation means has a line buffer for buffering the image signal. 6. A line sensor including a one-dimensional array of photoelectric conversion elements for generating a color image signal by continuously scanning a document and performing photoelectric conversion, and a balance between the color image signals generated by the line sensor. Determining means for determining the type of the document; charge storage time control means for controlling the charge storage time of the photoelectric conversion element for each color according to the type of the document; buffering the image signal generated by the line sensor Averaging means for performing an averaging process between lines for an image signal of a predetermined color based on the buffered image signal according to the type of the original and the image signal generated by the line sensor. An image signal processing device comprising: 7. The image signal processing apparatus according to claim 6, wherein the line sensor scans by moving relative to the document. 8. The image signal processing apparatus according to claim 6, further comprising a light source for irradiating the document with light, wherein the line sensor performs photoelectric conversion based on light transmitted through the document. 9. The method according to claim 8, wherein the determining unit determines whether the original is a negative film or a positive film, and the light source has a spectral characteristic in consideration of a white balance of either the negative film or the positive film. The image signal processing device according to any one of the preceding claims. 10. The image signal processing apparatus according to claim 9, wherein said line sensor generates blue, green, and blue image signals. 11. The light source has a spectral characteristic in consideration of the white balance of a negative film. When it is determined that the original is a positive film, the charge accumulation time of a blue image signal is reduced by the charge accumulation of a red image signal. The image signal processing apparatus according to claim 10, wherein the time is shorter than the time, and an averaging process between lines of the blue image signal is performed. 12. The image signal processing apparatus according to claim 11, wherein when it is determined that the original is a negative film, the charge accumulation times of blue and red are made the same, and averaging between image signal lines is not performed. 13. The light source has a spectral characteristic in consideration of the white balance of a positive film. When it is determined that the document is a negative film, the charge accumulation time of a red image signal is increased by the charge accumulation of a blue image signal. 11. The image signal processing apparatus according to claim 10, wherein the time is shorter than the time, and the averaging process between the lines of the red image signal is performed. 14. The image signal processing apparatus according to claim 13, wherein when it is determined that the original is a positive film, the charge accumulation times of red and blue are made equal, and averaging between image signal lines is not performed. 15. An image signal processing method for an image signal processing apparatus including a one-dimensional array of photoelectric conversion elements for generating a color image signal by continuously scanning a document and performing photoelectric conversion, wherein: Determining the type of the document based on the balance of the color image signals generated by the photoelectric conversion elements; and (b) controlling the charge accumulation time of the photoelectric conversion elements for each color according to the type of the document. (C) performing an averaging process between lines for an image signal of a predetermined color according to the type of the document.