JP2006086839A - Defective pixel correction device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a defective pixel correction device capable of preventing erroneous detection in defective pixel detection and correction by an approximate value in defective pixel correction. <P>SOLUTION: The defective pixel correction device has two solid-state image pickup elements for a moving image and a still image. The characteristic is utilized for preventing the erroneous detection and the correction by the approximate value. When a prominent pixel signal is detected during operation of one of the image pickup elements, the determination of the defective pixel is executed by comparing the prominent pixel signal with the pixel signal of the other image pickup element. When a prominent pixel is a defective pixel as a result of the determination, the defective pixel signal is corrected by using the pixel signal obtained from the other image pickup element. The erroneous detection of the defective pixel can be prevented by such a method. It is also possible to correct the defective pixel with an actual pixel signal value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a defective pixel correction apparatus according to means for detecting and correcting a defective pixel of a solid-state imaging device such as a CCD.

  It is unavoidable that a large number of pixels constituting a solid-state imaging device such as a CCD include a defective product that does not generate an electrical signal of a predetermined level. On the display screen corresponding to such pixels. These pixels are defective pixels having no normal luminance. The defective pixel includes a white point defective pixel that outputs an electric signal having a magnitude greater than or equal to a predetermined amount with respect to the incident light quantity, and a black spot defective pixel that outputs only an electric signal with a magnitude less than or equal to the predetermined amount with respect to the incident light quantity. These defective pixels are generally called scratches and protrude one pixel from surrounding pixels.

  A conventional example in CCD defective pixel correction will be described below. A schematic configuration diagram of conventional defective pixel correction is shown in FIG. The light passing through the lens 1 reaches the CCD 6 through the diaphragm 2. The signal obtained from the CCD is A / D converted 7. From the A / D converted signal, the detection circuit 8 detects the protruding pixels. If a protruding pixel is detected by the detection circuit, the signal is corrected by the correction circuit 10.

  The above-described conventional defective pixel detection method takes a difference between a target pixel and surrounding pixels and detects a pixel having an output larger or smaller than a certain level as a defective pixel. That is, a pixel signal protruding by one pixel is regarded as a defective pixel.

The defective pixel detected by the above detection method is corrected by replacing the portion with a surrounding value. There are several methods for that means. For example, there are a method of replacing with a pixel signal of one pixel or two pixels before and a method of replacing with an average value of front and rear or upper and lower pixel signals.
Japanese Patent Laid-Open No. 7-7675

  However, in the conventional method, when a high-resolution image is taken, when an image including a signal that actually protrudes by one pixel is captured, the signal is determined as a defective pixel and correction is performed. This causes a reduction in resolution. In addition, since the pixel signal near the defective pixel and the average value of the pixel signal near the defective pixel are replaced with the pixel signal of the defective pixel portion for the defective pixel, a pixel signal different from the actual image is displayed.

  In order to solve the above-described problems, the present invention aims to detect a defective pixel with high accuracy and to correct the defective pixel by an accurate pixel signal value.

  In recent years, video cameras have been devised that incorporate two image sensors, a moving image sensor and a still image sensor. In the present invention, a video camera incorporating these two image sensors is targeted, and the defective pixels are corrected by utilizing the fact that this video camera can project one image onto two image sensors.

  That is, the technical contents of the present invention can solve the above-described problems by including the following configuration.

  (1) In an image pickup apparatus having a moving image pickup element, a still image pickup element, and a protruding pixel signal detection circuit, the protruding pixel signal is detected by one of the image pickup elements. A defective pixel correction apparatus characterized by defective pixel detection means for determining whether or not a protruding pixel is a defective pixel by comparing with a signal of one image sensor.

  In the present invention, since the defective pixel is determined by detecting the protruding pixel and comparing it with the pixel signal of the other image sensor, the erroneous detection of the defective pixel can be reduced, and the image with high resolution can be reduced. Can be displayed as they are.

  In addition, after detecting a defective pixel, the pixel determined to be a defective pixel can be corrected using the corresponding pixel of the other image sensor without correcting with a signal of an approximate value as in the past. Pixel signals can be displayed.

  Further, both the moving image and the still image can be detected and corrected as described above.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic configuration diagram of the present embodiment. The light passing through the lens 1 passes through the half mirror 3 through the diaphragm 2. The light is separated by the half mirror 3 and reaches the movie CCD 5 and the still CCD 6. A shutter 4 is provided in front of the Still CCD 6 to prevent light from being exposed during the reading of the CCD. A signal obtained from the CCD is converted into a digital signal by A / D conversion 7, and a detection circuit 8 that detects protruding pixels, and a comparison circuit that compares pixel signal values obtained from moving image and still image imaging devices. 9. Pass through a correction system having a correction circuit 10 for correcting defective pixels. Of the signals that have passed through the correction system, the still image is signal-processed by the Still signal processing 11 and recorded in the memory card 13. The moving image is signal-processed by the movie signal processing 12 and recorded on the magnetic tape 14 or displayed on the display 15.

  Next, the correction system will be described. FIG. 2 shows a flowchart of the correction system. First, photographing is started (S1), and a signal is obtained by one CCD. The signal is sent to a conventional detection circuit, and the protruding pixel signal is detected (S2). If no protruding pixel signal is detected, it is sent to the signal processing circuit (S6). When the protruding pixel signal is detected, the same image signal is obtained from the other CCD (S3). The detected pixel signal and the obtained pixel signal are compared (S4). As a result, if the signal values are the same, they are sent to the signal processing circuit (S6) without being corrected. If the obtained signal and the signal of the protruding pixel are different, it is determined that the signal is a defective pixel, and the defective pixel is corrected using the pixel signal obtained by the other CCD (S5). The corrected signal is sent to the signal processing circuit (S6).

  As an actual example, a description will be given of a case where a pixel protruding from the moving image CCD is detected. FIG. 3 shows a schematic diagram of a moving image CCD and a still image CCD. FIG. 3A shows an example of defective pixel correction when a defective pixel is detected in the moving image CCD. For simplicity, the moving image CCD and the still image CCD have a 1: 4 pixel number and the same angle of view.

  At the time of moving image shooting, first, the conventional detection of protruding pixels is performed in the moving image CCD. When a protruding pixel is detected, the luminance signal of the still image CCD pixel corresponding to the position of the protruding pixel on the moving image CCD is viewed. In the example of FIG. 3, four pixels of the still image CCD are supported. The signal of the four pixels of the still image CCD is integrated, and the value is compared with the signal of the protruding pixel of the moving image CCD. If the result is the same, the pixel signal of the moving image CCD is displayed as it is because it is not a defective pixel. If the comparison results are different, the pixels in the defective pixel portion are corrected using signals for four pixels obtained from the still image CCD. Even if the angle of view and the pixel ratio of the two image sensors differ, correction can be performed in the same way by taking correspondence between the pixels of the moving image sensor and the still image sensor.

  Next, a case where a protruding pixel is detected by the still image CCD will be described. FIG. 3B shows an example of defective pixel correction when a defective pixel is detected in the still image CCD. As with moving image shooting, the moving image CCD and the still image CCD have a pixel number ratio of 1: 4 and the same angle of view.

  As in the case of moving image shooting, when a still image is shot, the protruding pixels are detected by the still image CCD as in the conventional case. When a protruding pixel is detected, the luminance signal value of the moving image CCD pixel corresponding to the protruding pixel position on the still image CCD is viewed. Since a still image CCD has a smaller pixel on the screen than a moving image CCD, it cannot accommodate a moving image CCD pixel. Therefore, the luminance signal values of four pixels of the still image CCD corresponding to one pixel of the moving image CCD at the position including the protruding pixel signal of the still image CCD are observed. The luminance signal value of one pixel of the moving image is compared with the luminance signal value of four pixels of the still image. If the comparison result is the same, it is not a defective pixel and is displayed as it is. If the comparison results are different, the signal of the defective pixel is corrected using a value obtained by subtracting the signal of three pixels excluding the signal of the defective pixel from one pixel obtained from the moving image CCD from the four pixels obtained from the still image CCD. . As in the case of moving image shooting, even if the angle of view and the pixel ratio of the two image sensors differ, correction can be performed in the same manner by taking correspondence between the pixels.

  In this embodiment, an example of claim 5 is shown. FIG. 4 shows a schematic configuration diagram of the imaging system in the present embodiment. Parts similar to those in the first embodiment are omitted. The A / D converted signal is corrected through a correction system having a detection circuit 8 and a correction circuit 10, and thereafter output in the same manner as in the first embodiment.

  A flowchart of the correction system is shown in FIG. When shooting is started (S11), the detection circuit detects a defective pixel (S12). When a defective pixel is detected, a pixel signal of the same image is obtained from the other CCD (S13). The defective pixel is corrected using the obtained signal (S14). The corrected signal is sent to the signal processing circuit (S15). In this embodiment, unlike the first embodiment, correction is performed without comparing two CCD pixel signals. However, even if the protruding pixel signal is not a defective pixel, since the signal obtained using the other CCD is also a protruding pixel signal, the protruding pixel signal is corrected with the same signal. So no problem arises. Even if such a method is used, it is possible to correct an appropriate defective pixel as in the first embodiment.

  As described above, according to the present invention, it is possible to prevent erroneous detection of defective pixels even for high-resolution images and to correct defective pixels with actual pixel signal values.

It is an example using CCD of the schematic block diagram of the defective pixel correction system by this invention. It is an example of the flowchart which shows the defective pixel correction process of this invention. It is an image figure of the pixel correction of the moving image and still image in the pixel correction means of this invention. It is an example using CCD of the schematic block diagram of the defective pixel correction system by this invention. It is an example of the flowchart which shows the defective pixel correction process of this invention. It is a schematic block diagram of the conventional CCD defective pixel correction.

Explanation of symbols

1 Lens 2 Aperture 3 Half mirror 4 Shutter 5 Movie CCD
6 Still CCD
7 A / D conversion processing unit 8 Detection circuit 9 Comparison circuit 10 Correction circuit 11 Still signal processing 12 Movie signal processing 13 Memory card 14 Magnetic tape 15 Display

Claims (7)

  In an image pickup apparatus having a moving image pickup device, a still image pickup device, and a circuit that detects a protruding pixel signal, the protruding pixel signal is detected by one of the image pickup devices, and if there is a protruding pixel signal, the other image is picked up. A defective pixel correction device comprising defective pixel detection means for comparing with a signal of an element to determine whether or not a protruding pixel is a defective pixel.   2. The defective pixel correction apparatus according to claim 1, further comprising defective pixel correction means for correcting a signal determined to be a defective pixel using a pixel signal of the other image sensor.   The defective pixel correction apparatus according to claim 2, wherein the defective pixel correction apparatus includes correcting a defective pixel of the moving image pickup device using a pixel signal of the still image pickup device.   3. The defective pixel correction apparatus according to claim 2, further comprising: correcting a defective pixel of the still image pickup device using a pixel signal of the moving image pickup device.   In an image pickup apparatus having a moving image pickup device, a still image pickup device, and a circuit for detecting a signal of a defective pixel, when a pixel signal protruding from one image pickup device is detected, the pixel signal of the other image pickup device is used. A defective pixel correction device characterized by correction means for performing correction.   6. The defective pixel correction apparatus according to claim 5, further comprising: correcting defective pixels of the moving image pickup device using a pixel signal of the still image pickup device.   6. The defective pixel correction apparatus according to claim 5, further comprising: correcting a defective pixel of the still image pickup device using a pixel signal of the moving image pickup device.