JP2002142157A - Pixel defect correcting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pixel defect correcting device capable of realizing proper pixel defect correction according to the luminance level of a video, and obtaining an outline picture by suppressing any side effect due to the correction as much as possible. SOLUTION: This pixel defect correcting device is provided with a defect detecting circuit for outputting the position and signal data of a defective pixel from a pixel signal being the output of an image pickup element, a luminance level detecting circuit for detecting the luminance level of a specific area, a data storing circuit for storing the detection data, and for outputting a correction control signal for controlling the correction of the defective pixel detected according to the luminance level information, and an address storing circuit for outputting only the position data of the defective pixel whose correction is necessary according to the luminance level information as a correction address from the correction control signal. Thus, it is possible to correct the defective pixel according to the luminance level, and to obtain a satisfactory picture by reducing any side effect corresponding to the correction as much as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting and correcting a pixel defect existing in an image sensor in an image sensor using an image sensor such as a CCD.

[0002]

2. Description of the Related Art In an image pickup device such as a CCD, a pixel defect due to adhesion of dust, a crystal defect, or the like may exist. If the pixel defect exists, a white defect which outputs a signal as white regardless of an image, or an image defect. Regardless, it appears as a black flaw that outputs a signal as black. If there is such a pixel defect, the image quality is significantly deteriorated. It is difficult to completely remove this pixel defect. Under such circumstances, various techniques for correcting a pixel defect have recently been proposed.

A conventional pixel defect correction device will be described below. FIG. 10 is a block diagram of a conventional pixel defect correction device. In FIG. 10, reference numeral 1 denotes an image sensor such as a CCD, 2 a defect detection circuit for detecting a pixel defect, 3 an address storage circuit for storing the position of the defective pixel and converting it to a correction address, and 4 an output of the address storage circuit 3. A defect correction circuit 5 for correcting a defective pixel portion in a pixel signal based on the correction address is a signal processing circuit.

The operation of the conventional pixel defect correction device configured as described above will be described below.

First, in a state where a specific image such as a light-shielded state is captured by the image sensor 1, the defect detection circuit 2 detects the position of the defective pixel from a pixel signal output from the image sensor 1, and detects the detected defective pixel. Address storage circuit 3
Write to. Next, in the normal operation state, the defective portion of the pixel signal, which is the input signal, is adjusted by the defect correction circuit 4 according to the correction address, which is the position data of the defective pixel read from the address storage circuit 3, for example, of the adjacent pixel group. Correction processing is performed by averaging or the like. The signal corrected in this way is sent to the signal processing circuit 5, where predetermined signal processing is performed.

Hereinafter, the address storage circuit 3 will be described in more detail with reference to FIG. FIG. 11 is a block diagram showing an example of the internal configuration of the address storage circuit 3 when the pixel defect correction is left as shown in FIG. As the operation, the positions of N defective pixels detected by the defect detection circuit 2 are stored as the detection address 1, the detection address 2,..., The detection address N, and all the detection addresses are normally operated by the address conversion circuit 10. It has a function of being converted into position information in the state and outputting it as correction addresses AD_1,..., AD_N.

[0007]

However, since the influence of a defective pixel differs depending on the luminance level of an image, a conventional defective pixel correction apparatus performs correction for all detected defective pixels. For example, since the correction is performed even when the pixel defect is not conspicuous at the time of high illuminance, there is a problem that the image quality is deteriorated due to side effects such as frequency characteristic deterioration of the image caused by the correction. Further, if the defective pixel detection level is set so that appropriate correction can be performed at the time of high illuminance, there is a problem that appropriate correction cannot be performed at the time of low illuminance.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and can perform appropriate pixel defect correction in accordance with the luminance level of an image.
It is an object of the present invention to provide a pixel defect correction device capable of obtaining a good image.

[0009]

In order to achieve the above object, a pixel defect correcting apparatus according to the present invention comprises: an image pickup device for converting an optical signal incident from a subject into an electric signal and outputting it as a pixel signal; Defect detection means for detecting a defective pixel from a pixel signal from the CPU and outputting position information and a signal level of the defective pixel as a detection address and detection data, respectively, and a pixel signal from the image sensor as an input, and luminance level information of a specific area. A brightness level detection unit that outputs the correction data; a data storage unit that stores the detection data output from the defect detection unit and outputs a correction control signal in accordance with the brightness level information output from the brightness level detection unit; The position information of the corrected pixel is corrected based on the correction control signal from the data storage unit and the detection address from the defect detection unit. Address storage means for outputting as a correction signal, a defect correction means for outputting a signal obtained by correcting a defective pixel included in a pixel signal in accordance with the correction address output from the address storage means as a correction signal, and a defect correction means. And a signal processing means for generating a luminance signal from the correction signal.

With such a configuration, a pixel defect correction apparatus capable of performing appropriate pixel defect correction in accordance with the luminance level of an image, suppressing the side effects of the correction as much as possible, and obtaining a good image. Can be provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A defective pixel correction apparatus according to any one of claims 1 to 5 of the present invention converts an optical signal incident from a subject into an electric signal and outputs the signal as a pixel signal. Defect detection means for detecting a defective pixel from the pixel signal and outputting the position information and the signal level of the defective pixel as a detection address and detection data, respectively, and inputting a pixel signal from the image sensor to obtain luminance level information of a specific area. Brightness level detecting means for outputting, data storage means for storing the detection data output from the defect detecting means, and outputting a correction control signal according to the brightness level information output from the brightness level detecting means; The position information of the corrected pixel is output as a correction address based on the correction control signal from the storage unit and the detection address from the defect detection unit. Address storage means, a defect correction means for outputting, as a correction signal, a signal obtained by correcting a defective pixel included in a pixel signal in accordance with the correction address output from the address storage means, and a correction signal from the defect correction means. And a signal processing means for generating a luminance signal from the pixel. With this configuration, the luminance level is detected, and the correction of the detected defective pixel is controlled, thereby correcting the defective pixel according to the luminance level. And good images can be obtained.

An embodiment of the present invention will be described below in detail with reference to FIGS.

(First Embodiment) FIG. 1 is a block diagram of a defective pixel correction device according to a first embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes an image sensor such as a CCD for converting an optical signal of a subject into an electric signal, and 3a an address storage means for storing a position of a defective pixel detected by a defect detection circuit 2a and converting the position to a correction address. The storage circuit 4 is a defect correction circuit that is a defect correction unit that corrects a defective pixel portion in a pixel signal based on a correction address output from the address storage circuit 3a, and 5 is a pixel signal corrected by the defect correction circuit 4. Is a signal processing circuit that is a signal processing means for performing signal processing, and 6 is a luminance level detecting circuit that is a luminance level detecting means that receives a pixel signal from the image sensor 1 and outputs a luminance level of a specific area as luminance level information. A defect detection circuit, which is a defect detection means for detecting a defective pixel from a pixel signal from the image pickup device 1, wherein the conventional detection circuit uses position data While has output only a certain detection address, control also in adding that outputs a signal level of a defective pixel as detection data with the detection address.

The operation of the defective pixel correction device configured as described above will be described below with reference to FIGS.

First, in a light-shielded state or the like, the position and signal level of a defective pixel are detected by a defect detection circuit 2a from a pixel signal which is an output signal of the image sensor 1. Then, the position of the detected defective pixel is input to the address storage circuit 3a, and the signal level of the defective pixel is input to the data storage circuit 7. Next, the light blocking state is released, and the normal photographing state is set. In order to obtain the brightness information in the normal shooting state, the brightness level detection circuit 6 detects the brightness level information from the output signal of the image sensor 1 and the pixel signal. Then, the data storage circuit 7 performs control to calculate information on whether or not to correct the defective portion based on the luminance level information and the signal level of the defective pixel, and outputs this information as a correction control signal.

The correction control signal is input to the address storage circuit 3a together with the position information of the defective pixel. In this circuit, control is performed to make the defective pixel position information valid / invalid according to the correction control signal. Only the defective pixel position information is output as a correction address. Then, the correction address is input to the defect correction circuit 4, and the circuit corrects a defective portion of the image sensor 1 on the pixel signal based on the correction address. Finally, a correction signal obtained by correcting the defective portion is input to the signal processing circuit 6, where predetermined signal processing is performed to generate a luminance signal.

Next, the data storage circuit 7 and the address storage circuit 3a will be described in more detail with reference to FIGS.

The data storage circuit 7 is a circuit that stores the signal level of the detected defective pixel and outputs a correction control signal for controlling the correction of the detected defective pixel based on the luminance level information obtained from the luminance level detection circuit 6. FIG. 2 is a diagram showing an example of the internal configuration of the data storage circuit according to the present embodiment. In the data storage circuit of FIG. 2, the signal levels of the detected N defective pixels are represented by detection data 1, detection data 2,
.., Stored as the detection data N, and a correction coefficient adapted to the luminance level information is output from the correction coefficient generation circuit 11 as the correction coefficient generation means. Next, all the detected data and the correction coefficient are compared by the comparator 12 as a comparing means, and if the detected pixel is a position of a defective pixel to be corrected in accordance with the luminance level information, a signal S_1,.・ ・ 、
S_N is output as a correction control signal.

.., S_N in FIG. 2 may be output as a 1-bit control signal by an encoder, as shown in FIG.

The address storage circuit 3a is a circuit for outputting, as a correction address, only position data of a defective pixel which needs to be corrected in accordance with a luminance level under the control of a correction control signal obtained from the data storage circuit 7. FIG. 3 is a diagram showing an example of the internal configuration of the address storage circuit according to the present embodiment. In the address storage circuit of FIG. 3, as is apparent from comparison with the internal configuration diagram of the conventional address storage circuit (FIG. 11), all the correction addresses AD_1,.
.., ON / OFF of the correction address for AD_N, the correction control signal S_1 obtained from the data storage circuit 7,
.. Has a switch for switching according to S_N.

In the address storage circuit 3a, as shown in FIG. 5, the signals AD3_1,.
, As a 1-bit correction address by an encoder, a configuration having a changeover switch in the preceding stage of the address conversion circuit as shown in FIG. 6, or all the correction addresses AD_1,..., AD_N as shown in FIG. A configuration in which a control signal is input to an encoder and output as a 1-bit correction address is also conceivable.

As described above, according to the present embodiment, the defect detection circuit 2a that outputs the position of the defective pixel and the signal data from the pixel signal output from the image sensor 1, and the luminance that detects the luminance level of the specific area A level detection circuit 6, a data storage circuit 7 for storing detection data and outputting a correction control signal for controlling correction of a defective pixel detected in accordance with the luminance level information, and performing a correction in accordance with the luminance level information in accordance with the correction control signal By providing the address storage circuit 3a that outputs only the required position data of the defective pixel as the correction address, it becomes possible to correct the defective pixel according to the luminance level. Correction was performed on the defective area, and the correction was performed on the defective area that was not noticeable depending on the shooting conditions. Raised in contrast had, by correcting only the defective portion conspicuous in this embodiment, it is possible to obtain a good image of suppressing as much as possible adverse reactions to correction.

(Embodiment 2) FIG. 8 is a block diagram of a defective pixel correction apparatus according to Embodiment 2 of the present invention. 8, different points from the first embodiment of the present invention will be described, and the same reference numerals will be given to configurations having the same effect, and detailed description will be omitted.

In FIG. 8, the difference from the configuration of FIG. 1 is that the luminance level detection circuit 6 detects luminance level information from a pixel signal which is an output signal of the image pickup device 1 in the configuration of the first embodiment. On the other hand, the configuration of the second embodiment is that the luminance level information is detected from the luminance signal output from the signal processing circuit 5. And also in this configuration,
This is exactly the same as Embodiment 1 of the present invention, and the same effects can be obtained.

As described above, according to the present embodiment, there is provided a luminance level detecting circuit for detecting the luminance level of a specific area from the luminance signal output from the signal processing circuit 5 instead of the output signal from the image sensor 1. Thus, the first embodiment
The same effect can be obtained.

(Embodiment 3) FIG. 9 is a block diagram of a defective pixel correcting apparatus according to Embodiment 3 of the present invention. In FIG. 9, points different from Embodiment 1 of the present invention will be described, and the same reference numerals will be given to configurations having the same effect, and detailed description will be omitted.

In FIG. 9, reference numeral 8 denotes an automatic gain control circuit (hereinafter, referred to as an AGC circuit) which is an automatic gain control means for controlling a pixel signal output level outputted from the image pickup device 1 to a constant level and outputting it as a video signal. , 9 are gain level detecting circuits which are gain level detecting means for detecting the magnitude of the gain in the AGC circuit and outputting it as an AGC gain.

FIG. 9 differs from the configuration of FIG. 1 in that the correction coefficient used inside the data storage circuit 7 is adapted to the AGC gain and that the video signal output from the AGC circuit 8 is The point is that detection and correction of defective pixels are performed. In the case of the above configuration, the same effect as in the first embodiment of the present invention can be obtained.

As described above, according to the present embodiment, the AGC circuit for automatically controlling the pixel signal output level to be constant and the gain level detecting circuit for detecting the magnitude of the gain in the AGC circuit are provided. Accordingly, the same effect as in the first embodiment can be obtained.

[0030]

As described above, according to the present invention, by controlling the correction of a defective pixel detected in accordance with luminance level information such as a pixel signal, side effects due to the correction are suppressed as much as possible, and higher accuracy is achieved. An excellent effect that defective pixel correction can be performed and a good image can be obtained is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a defective pixel correction device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a data storage circuit 7 of FIG. 1;

FIG. 3 is a block diagram showing an internal configuration of an address storage circuit 3a of FIG. 1;

FIG. 4 is a block diagram showing an internal configuration of the data storage circuit 7 of FIG. 1;

FIG. 5 is a block diagram showing an internal configuration of an address storage circuit 3a of FIG. 1;

FIG. 6 is a block diagram showing an internal configuration of an address storage circuit 3a of FIG. 1;

FIG. 7 is a block diagram showing an internal configuration of an address storage circuit 3a of FIG. 1;

FIG. 8 is a block diagram of a defective pixel correction device according to a second embodiment of the present invention.

FIG. 9 is a block diagram of a defective pixel correction device according to a third embodiment of the present invention.

FIG. 10 is a block diagram of a conventional defective pixel correction device.

11 is a block diagram showing an internal configuration of the address storage circuit 3 in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image sensor 2, 2a Defect detection circuit 3, 3a Address storage circuit 4 Defect correction circuit 5 Signal processing circuit 6 Brightness level detection circuit 7 Data storage circuit 8 AGC circuit 9 Gain level detection circuit 10 Address conversion circuit 11 Correction coefficient generation circuit 12 Comparator 13 Encoder

Claims (5)

[Claims] 1. An image sensor that converts an optical signal incident from a subject into an electric signal and outputs the signal as a pixel signal, detects a defective pixel from a pixel signal from the image sensor, and determines position information and a signal level of the defective pixel. Defect detection means for outputting as a detection address and detection data, luminance level detection means for receiving a pixel signal from the image sensor and outputting luminance level information of a specific area, and detection data output from the defect detection means Data storage means for storing a correction control signal in accordance with the brightness level information output from the brightness level detection means, and a correction pixel based on a correction control signal from the data storage means and a detection address from the defect detection means. Address storage means for outputting the position information as a correction address, and output from the address storage means. Defect correction means for outputting, as a correction signal, a signal obtained by correcting a defective pixel included in a pixel signal in accordance with the correction address, and signal processing means for generating a luminance signal from the correction signal from the defect correction means. A pixel defect correction device, characterized in that: 2. An image pickup device for converting an optical signal incident from a subject into an electric signal and outputting it as a pixel signal, detecting a defective pixel from a pixel signal from the image pickup device, and detecting position information and a signal level of the defective pixel. A defect detection unit that outputs a detection address and detection data, a luminance level detection unit that outputs luminance level information of a specific area in an input pixel signal, and the detection data that is output from the defect detection unit. A data storage unit for outputting a correction control signal in accordance with the luminance level information output from the luminance level detection unit; and a correction control signal from the data storage unit and a detection address from the defect detection unit. Address storage means for outputting as a correction address, and the correction output from the address storage means Defect correction means for outputting a signal obtained by correcting a defective pixel included in a pixel signal in accordance with an address as a correction signal, and signal processing means for generating a luminance signal based on a correction signal from the defect correction means; A pixel defect correction device, wherein a luminance signal output from a processing unit is input to the luminance level detection unit. 3. A data storage means, comprising: a correction coefficient generation means for outputting a coefficient corresponding to luminance level information; and a correction control signal for comparing a coefficient generated by the correction coefficient generation means with detection data detected by the defect detection means. 3. The pixel defect correction device according to claim 1, further comprising a comparison unit that outputs the pixel defect. 4. An image pickup device that converts an optical signal incident from a subject into an electric signal and outputs the signal as a video signal, and automatically controls a pixel signal output level output from the image pickup device to a constant level as a video signal. Automatic gain control means for outputting, a defect detection means for detecting a defective pixel from a video signal from the automatic gain control means and outputting position information and a signal level of the defective pixel as a detection address and detection data, respectively, and the automatic gain Gain level detecting means for detecting the magnitude of the gain in the control means and outputting it as an AGC gain, and storing detection data output from the defect detecting means and correcting according to the AGC gain output from the gain level detecting means Data storage means for outputting a control signal,
An address storage unit for outputting position information of a correction pixel as a correction address based on a correction control signal from the data storage unit and a detection address output from the defect detection unit, and a correction address output from the address storage unit. A pixel defect comprising: a defect correction unit that outputs a signal obtained by correcting a defective pixel included in a video signal as a correction signal; and a signal processing unit that generates a luminance signal from the correction signal from the defect correction unit. Correction device. 5. A data storage means comprising: a correction coefficient generation means for outputting a coefficient corresponding to an AGC gain; and a comparison means for comparing a coefficient from the correction coefficient generation means with detection data and outputting a correction control signal. The pixel defect correction device according to claim 4, wherein