JP2006211460A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the white flaw of a CCD while operating a camera. <P>SOLUTION: When a mode is not a white flaw detecting mode (S101), positional information of the white flaw in a memory is checked and white flaw correction is performed by a white flaw correction circuit (S112). When the mode is in the white flaw detecting mode, levels of luminance signals are compared (S102), gain data from an AGC circuit are detected (S103), and temperature data of an imaging device are acquired from a temperature detecting sensor (S104). On the basis of these data, a defective pixel detection threshold level is calculated (S105). When the number of times of detection does not reach the predetermined number of times (S106), white flaw detection is performed by a white flaw detection circuit (S107), and a detected defective pixel position is temporarily stored (S108). Panning and tilting are performed (S109), processing is returned to S103 and the next detection is performed. When the number of times of detection reaches the predetermined number of times, a detected pixel position and the level in each of detection are compared (S110) and when they match each other, a pixel defect is determined and written into the memory (S111), and white flaw correction is performed (S112). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus used in, for example, a video conference or a remote monitoring system.

  In a television camera, a subject image is exposed to an image sensor such as a CCD or CMOS sensor for a desired time, and an image signal obtained thereby is converted into a digital signal, subjected to a predetermined process such as a YC process, and a predetermined format. The image signal is obtained.

  As a defective pixel correction function of the image sensor, the incident light from the subject is blocked by a light blocking means such as a diaphragm, and the image signal obtained in that state is compared with the detection level of the abnormal signal of the image due to the pixel defect. It is widely known that if it is above, it is determined as a defective pixel and the defective pixel position is stored and corrected.

  In addition, the image sensor performs photoelectric conversion, but has a property of converting heat energy into an electrical signal. The signal component converted into an electrical signal by this thermal energy is called dark current, and it is known that the temperature dependence is strong, and its value almost doubles when the temperature rises by 10 ° C.

  In general, white flaws are caused by a dark current that is abnormally increased compared to other pixels due to a pixel defect, and the level is also changed by temperature, automatic gain control (AGC), and low-speed shutter control. In consideration of such points, in a television camera that corrects pixel defects of an image sensor by signal processing, a technique for changing a threshold level for white defect determination in accordance with the image sensor or its ambient temperature and AGC gain is disclosed in Patent Document 1. Is disclosed.

Japanese Patent No. 3014895

  However, in the above-mentioned Patent Document 1, since a normal signal component similarly changes depending on the temperature and AGC, it is difficult to detect a white flaw during normal photographing.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus capable of performing white defect detection based on pixel defects of an image sensor and satisfactorily correcting white defects based on the defect so as to solve the above-described problems and not affect normal shooting. It is to provide.

  In order to achieve the above object, the technical features of the imaging apparatus according to the present invention include an imaging device that converts an optical signal imaged on an imaging surface into an electrical signal, and a light for guiding a subject image to the imaging device. An optical system; defective pixel detection means for detecting defective pixels of the image sensor; defective pixel position storage means for storing position information of the detected defective pixels; and a signal corresponding to the defective pixels around the defective pixels A calculation unit including a defective pixel correction unit that corrects the pixel based on a pixel signal or a calculation value; and an imaging direction changing unit that can change an imaging direction of the optical system. During the imaging direction change by the imaging direction changing unit When the amount of light incident on the image sensor becomes a predetermined value or less, the defective pixel detection means detects the defective pixel.

  Further, the technical features of the imaging apparatus according to the present invention include an imaging device that converts an optical signal imaged on an imaging surface into an electrical signal, an optical system that guides light of a subject image to the imaging device, and A defective pixel detecting unit for detecting a defective pixel of the image sensor; a defective pixel position storing unit for storing the detected positional information of the defective pixel; and a signal corresponding to the defective pixel as a signal or calculation of a peripheral pixel of the defective pixel A calculation unit including a defective pixel correction unit that corrects by a value, an imaging direction changing unit that changes an imaging direction of the optical system, and a motion detection unit that detects a movement of the imaging element on a screen, The non-detection of motion by the motion detection means, and the detection of the defective pixels by the defective pixel detection means when the amount of light incident on the image sensor becomes a predetermined value or less.

  Furthermore, the technical features of the imaging apparatus according to the present invention include an imaging element that converts an optical signal imaged on an imaging surface into an electrical signal, an imaging field angle changing unit that changes an imaging field angle, and a subject image. An optical system for guiding light to the image sensor, a defective pixel detection unit that detects a defective pixel of the image sensor, a defective pixel position storage unit that stores position information of the detected defective pixel, and a defective pixel A defective pixel correction unit that corrects a corresponding signal based on a signal or a calculation value of a peripheral pixel of the defective pixel, and the amount of incident light on the imaging element is changed during the change of the imaging field angle by the imaging field angle changing unit. When the predetermined value or less is reached, the defective pixel detection means detects the defective pixel.

  According to the imaging apparatus of the present invention, if there is no change in AGC with respect to normal image fluctuations due to focusing, zooming, and movement of the angle of view, there is no change in the defective pixel position and level of the imaging element. By detecting the level change of each pixel at the time of the change, it becomes possible to accurately detect the white defect due to the pixel defect of the image sensor.

  The present invention will be described in detail based on the embodiments shown in the drawings.

  FIG. 1 is a block diagram of the camera system according to the first embodiment. As a photographing optical system, a fixed front lens 1 constituting a first lens group, a zoom lens driven by a stepping motor 2 constituting a second lens group. An imaging element 9 such as a lens 3, a diaphragm 5 driven by a diaphragm driving means 4, a fixed third group lens 6, a focus lens 8 that performs focus adjustment via a stepping motor 7, a CCD, a CMOS sensor, and the like are arranged. .

  The output of the image sensor 9 is connected to a D / A converter 16 via an AGC (automatic gain control) circuit 11, an A / D converter 12, a white defect detection circuit 13, a white defect correction circuit 14, and a signal processing circuit 15. The output of the signal processing circuit 15 is an evaluation processing circuit 17 that detects an evaluation value of AE (automatic exposure adjustment) / AWB (auto white balance adjustment), and an AF evaluation value detection process that detects an evaluation value of AF (focusing). The output of the processing circuits 17 and 18 is connected to a circuit 18 and is composed of a microcomputer, and is connected to a controller 19 that comprehensively controls the entire system such as AF, AE, and AWB.

  The output of the synchronizing signal generation circuit (Timing Generator) 20 is connected to the image sensor 9, automatic gain control circuit 11, and A / D converter 12. The output of the controller 19 is connected to the stepping motor 2, the aperture driving means 4, the stepping motor 7, and the electric swivel head 21 having a panning and tilting mechanism. Further, the controller 19 is connected to the output of the white defect detection circuit 13, the white defect correction circuit 14, and the temperature detection sensor 22 disposed in the vicinity of the image sensor 9, and is connected to the memory 23.

  In the above-described configuration, the optical image of the subject is formed on the imaging surface of the imaging device 9 by the lenses 1, 3, 6, and 8, and is converted into an electrical signal. Here, when the diaphragm 5 is fully opened and the luminance signal level of the amount of light received by the image sensor 9 does not reach a predetermined value, the AGC circuit 11 performs signal amplification in accordance with the brightness of the subject, and A / D The signal is converted into a digital signal by the converter 12.

  A normal video signal passes through a white defect detection circuit 13 and a white defect correction circuit 14 and is subjected to appropriate processing in accordance with a video signal standard such as color separation, white balance, and gamma correction in a signal processing circuit 15, and then D The A / A converter 16 converts the video signal into an appropriate format and outputs it.

  Compared with surrounding pixels in the white flaw detection circuit 13, a large signal of only one pixel can be determined as a white flaw. As a result, the detected white flaw is corrected by the white flaw correction circuit 14. In the white defect correction circuit 14, for example, when the gain of the AGC circuit 11 is doubled, the threshold level is doubled, and when the temperature rises by 10 ° C., the threshold level is doubled. Is used to calculate the threshold level for white flaw detection. The defective pixel position detected by the white defect detection circuit 13 is stored in the memory 23. In addition, the white defect correction circuit 14 corrects the peripheral pixel signal or the calculated value of the defective pixel according to the defective pixel position stored in the memory 23.

  The AF evaluation value detection processing circuit 18 is a gate circuit that gates a video signal corresponding to a predetermined distance measurement frame set in the imaging surface from the video signal, and has a sharpness necessary for performing focus detection. It is configured by a BPF (band pass filter) or the like for extracting a high frequency component as an evaluation value to be shown.

  FIG. 2 is a flowchart showing detection of white flaws and a correction operation based on the detection. It should be noted that it is preferable to detect white flaws in a state where the temperature of each part of the camera system is sufficiently raised and the circuit system is stable. For example, it is also effective to add processing such as monitoring the energization time and the temperature rise of the image sensor 9 and performing detection when a predetermined value is exceeded.

  The white flaw detection instruction is confirmed (step S101). If the white flaw detection mode is selected, the process proceeds to step S102. If the white flaw detection mode is not selected, the process proceeds to step S112, and the white flaw position information already written in the memory 23 is obtained. If there is white scratch position information, white scratch correction is performed based on this (step S112).

  If it is the white flaw detection mode, the level of the luminance signal is compared with a predetermined value (step S102). If it is equal to or lower than the predetermined value, the process proceeds to step S103, and if not, the process proceeds to step S112. If the luminance signal level is equal to or lower than the predetermined value, the gain data from the AGC circuit 11 is detected (step S103), and the temperature data of the image sensor 9 or its vicinity is acquired from the temperature detection sensor 22 (step S104). Based on this data, the controller 19 calculates a defective pixel detection threshold level (step S105). Next, the number of detections is counted and checked (step S106).

  If the number of detections has not reached the predetermined number, the white flaw detection circuit 13 performs white flaw pixel detection (step S107). If there is no white flaw, the process proceeds to step S109. The white scratch pixel position is temporarily stored (step S108). Panning movement and tilting movement are performed (step S109), or after waiting for a turning operation instruction, the process returns to step S103 to perform the next detection.

  When the number of detections reaches a predetermined number, the detection pixel position / level for each detection is compared (step S110). If they do not match, the process proceeds to step S112. The pixel position is written in the memory 23 (step S111), and the white defect correction circuit 14 performs white defect correction (step S112).

  FIG. 3 is an explanatory diagram of the comparison / determination of the luminance signal level in step S102, and shows screen division for calculating one evaluation value for AE and AWB. As shown in the flowchart of FIG. 4, the exposure uniformity of the entire screen can be confirmed by comparing the luminance values for each of the finely divided areas (step S201). Next, it is checked whether or not the focus evaluation value is equal to or less than a predetermined position (step S202). If the focus evaluation value is small, it can be seen that the main subject is not observed, and white scratch detection is performed under these conditions. Therefore, it is possible to detect white scratches with high accuracy (step S203).

  As described above, in the white defect correction during the normal photographing, it is necessary to distinguish whether the obtained large signal is due to the optical signal incident on the image sensor 9 or due to the white defect. Therefore, for example, white defect detection is performed a plurality of times during the operation of the electric swivel head 21 and the detection defect pixel position and detection level are compared to facilitate discrimination from the incident light signal to the image sensor 9. Scratch detection can be performed appropriately. Alternatively, pixel defect detection is performed in accordance with the turning of the camera platform 21 during monitoring, thereby facilitating discrimination from the incident light signal to the image sensor 9 and appropriately detecting white flaws.

  FIG. 5 shows an example of a PTZ camera 31 that performs panning, tilting, and zooming. The PTZ camera 31 is capable of panning angle of view movement P and tilting angle of view movement T by an electric swivel head 21, and a video server 32. It is connected to the.

  FIG. 6 shows an outline of controlling the PTZ camera 31 from the video server 32 and synthesizing the panoramic video P0 from the output video, the panning field angle movement P, and the tilting field angle movement T. Each of Pa, Pb, and Pc is one image obtained from the PTZ camera 31. By combining them in the video server 32, a panoramic image P0 as shown in FIG. 6 can be obtained. Of course, the same applies to a device in which the PTZ camera 31 and the video server 32 are integrated.

  From this panoramic video P0, it is also effective to detect a white flaw by detecting a uniform position where the amount of received light of the luminance signal from the image sensor 9 is equal to or less than a predetermined value and directing the angle of view there. At the same time, it is also effective to perform detection based on the set date and time.

  In this way, in a monitoring system that is always in an imaging state or a camera system that uses only an electronic iris that does not have an aperture mechanism, it is possible to detect white flaws without interrupting the image.

  FIG. 7 is a flowchart of white defect detection and correction operation based on this in Example 2. 2 is substantially the same as the operation in the flowchart of FIG. 2, but in FIG. 2, the captured image is changed in step S109, whereas in FIG. 7, the imaging field angle is changed or defocus processing is performed (step S309). The following detection is performed.

  As described above, in the white defect correction during the normal photographing, it is necessary to distinguish whether the obtained large signal is due to the optical signal incident on the image sensor 9 or due to the white defect. Thus, white flaw detection is performed a plurality of times while changing the picked-up image by zooming processing, and the detection defect pixel position and the detection level are compared to facilitate discrimination from the incident light signal to the image pickup device 9. Scratch detection can be performed appropriately. Alternatively, by performing pixel defect detection in accordance with the zooming process being monitored, it is possible to easily discriminate the incident light signal from the image sensor 9 and to detect white defects appropriately.

  In addition, the white defect detection is performed a plurality of times in the focused state and the out-of-focus (defocused) state, and the detection defect pixel position and the detection level are compared, so that the incident light signal to the image sensor 9 is It is also possible to easily detect white scratches.

  FIG. 8 is a block diagram of the third embodiment. In addition to FIG. 1 of the first embodiment, the output of the signal processing circuit 15 is connected to the controller 19 via the moving object detection circuit 24.

  FIG. 9 is a flowchart of the operation. A white flaw detection instruction is confirmed (step S401). If there is no detection instruction, the process proceeds to step S413, where the white flaw position information already written in the memory 23 is checked. Based on this, white defect correction is performed (step S413).

  If there is a white flaw detection instruction, a moving object is detected to see if there is any movement on the screen (step S402), and the luminance signal is compared with a predetermined magnitude (step S403). If there is moving object detection and the luminance signal is small, the process proceeds to step S404 and subsequent steps, which are the same as those in step S303 and subsequent steps in FIG.

  In the third embodiment, when the moving object detection is performed by the moving object detection circuit 24, unnecessary shooting mistakes can be prevented by not detecting white flaws. As described above, by using the detection / non-detection determination result by the moving object detection circuit 24 as the white defect detection condition, it is possible to detect the white defect with high accuracy.

1 is a block configuration diagram of Embodiment 1. FIG. FIG. 3 is a flowchart of the first embodiment. It is explanatory drawing of an AE / AWB evaluation value detection division area. It is a flowchart figure with respect to a division area. It is explanatory drawing of a PTZ camera. It is explanatory drawing of the synthesized panoramic image. FIG. 6 is a flowchart of the second embodiment. FIG. 10 is a block diagram of a third embodiment. FIG. 10 is a flowchart of the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Zoom lens 8 Focus lens 9 Image pick-up element 11 AGC circuit 13 White defect detection circuit 14 White defect correction circuit 17 Evaluation processing circuit 18 AF evaluation value detection processing circuit 19 Controller 21 Electric turning pan head 23 Memory 24 Moving object detection circuit 31 PTZ camera

Claims (9)

  An image sensor that converts an optical signal formed on the imaging surface into an electrical signal, an optical system for guiding light of a subject image to the image sensor, a defective pixel detection unit that detects a defective pixel of the image sensor, A calculation unit comprising: defective pixel position storage means for storing position information of the detected defective pixel; and defective pixel correction means for correcting a signal corresponding to the defective pixel by a signal or calculation value of a peripheral pixel of the defective pixel; An imaging direction changing unit capable of changing an imaging direction of the optical system, and when the amount of incident light on the imaging element becomes equal to or less than a predetermined value while the imaging direction is changed by the imaging direction changing unit, the defective pixel detecting unit An image pickup apparatus that detects the defective pixel.   An image sensor that converts an optical signal formed on the imaging surface into an electrical signal, an optical system for guiding light of a subject image to the image sensor, a defective pixel detection unit that detects a defective pixel of the image sensor, A calculation unit comprising: defective pixel position storage means for storing position information of the detected defective pixel; and defective pixel correction means for correcting a signal corresponding to the defective pixel by a signal or calculation value of a peripheral pixel of the defective pixel; And an imaging direction changing means for changing the imaging direction of the optical system, and a motion detecting means for detecting a motion of the imaging element on the screen, and non-detection of the movement by the motion detecting means, and to the imaging element An image pickup apparatus, wherein the defective pixel is detected by the defective pixel detection means when the incident light quantity of the light becomes equal to or less than a predetermined value.   An image sensor that converts an optical signal imaged on the imaging surface into an electrical signal, an imaging field angle changing unit that changes an imaging field angle, an optical system that guides light of a subject image to the image sensor, and A defective pixel detecting unit for detecting a defective pixel of the image sensor; a defective pixel position storing unit for storing the detected positional information of the defective pixel; and a signal corresponding to the defective pixel as a signal or calculation of a peripheral pixel of the defective pixel A defective pixel correcting means for correcting based on the value, and the defective pixel detecting means detects the defective pixel when the amount of incident light on the imaging element becomes a predetermined value or less during the changing of the imaging angle of view by the imaging angle of view changing means. An imaging apparatus characterized by performing detection.   4. The apparatus according to claim 1, further comprising: a signal amplifying unit that amplifies an output of the image pickup device, and a unit that changes a detection reference of the defective pixel in accordance with a gain of the signal amplifying unit. The imaging device described.   4. The imaging according to claim 1, further comprising a temperature detection unit that detects a temperature of the imaging device or its surroundings, and a unit that changes a detection standard of the defective pixel in accordance with the temperature. apparatus.   The imaging apparatus according to claim 1, wherein the optical system is controlled so that a focus on the imaging element is not focused when the defective pixel is detected.   The image pickup apparatus according to claim 1, further comprising a date and time setting and clock measurement means, wherein the image pickup direction of the image pickup device and a detection date and time can be set.   The imaging apparatus according to claim 1, further comprising a network connection unit, and a unit that transmits position information and a detection signal level of the detected defective pixel to an external device.   A television camera equipped with the imaging device according to any one of claims 1 to 6.

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