JP2006191449A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for detecting whether or not clamp operation is normal, a means for alerting the occurrence of abnormality and a correction method of an image in which blooming has occurred, so as to solve the problem of the image falling in black to a first field signal level until the clamp operation becomes restored to normality when the clamp operation does not work normally (the blooming occurred) caused by the charges overflowed to an OB portion of an imaging device, such as a CCD, as a result of the incidence of strong light such as direct sunlight. <P>SOLUTION: In regard to the OB portion of the imaging device such as a CCD 101, the difference between the first field and an OB target value, or the difference between the first field and the OB values of the second field or thereafter, is obtained. From the calculation result thereof, whether or not the clamp operation is normal is detected. On the basis of the above detection, an operator can select inhibition of recording a photographed image, recording of an abnormal image or recording of a corrected image. When the image is to be corrected, one frame image is corrected using the fields exactly above the first field and exactly below the first field. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus that forms an image on a recording medium using an imaging element such as a CCD.

  It is an object of the present invention to detect an abnormal image in the first field of one frame signal formed by the image pickup device and select subsequent processing of the image in the image pickup device according to claim 1. However, the OB level and the clamping operation, which are factors that cause the first field to become an abnormal image, will be described.

  Take a video camera as an example. When an image sensor such as a CCD outputs a subject as an image, a portion that is shielded and is not exposed to light is used as an optical black reference for an image signal. This standard is called OB (Optical Black, OB).

  In FIG. 1, there is a solid-state imaging device 101 such as a CCD, for example. An imaging signal output from the imaging device 101 is input to a circuit 102 called a CDS (correlated double sampling) circuit, and reset noise is removed. After that, a predetermined offset voltage is added to the offset addition circuit 103 and the offset addition output is input to the variable amplifier 104.

  The CDS circuit 102 forms a CDS circuit that uses the predetermined reference voltage VREF input from 106 as a reference for the feedthrough portion of the imaging signal. Similarly, the variable amplifier 104 uses the reference voltage VREF as the imaging signal. This constitutes a direct current amplifier which is used as a reference for direct current amplification.

  The variable amplifier 104 is a gain variable means for correcting the output sensitivity variation of the CCD 101 and switching the sensitivity setting of the image pickup apparatus. Hereinafter, in order to explain the clamping operation of the image pickup apparatus simply and clearly, the gain 1 It shall be handled simply as a double.

  The amplified output signal from the variable amplifier 104 is input to the image processing / recording / display circuit 108 on the one hand and to the sample hold circuit 107 on the other hand, and is synchronized with the readout timing of the OB pixel input from 109. The OB level sampled and held by the OB clamp pulse is input to the integrating amplifier 105.

  The integrating amplifier 105 has a predetermined integration time constant by a capacitor 105b and a resistor 105c, and a differential voltage (clamp error voltage) between the sampled and held OB level and a predetermined reference voltage VREF input from 106. Is integrated with the integration time constant, and the output (deviation amount from the voltage VREF) is input to the offset addition circuit 103 and subtracted therefrom for negative feedback control.

  FIG. 2 shows how the OB level of the output signal 20C of the variable amplifier 104 is clamped to the DC voltage level VREF and converges, and the operation waveforms of the respective parts at that time.

  A signal waveform 20A is an output waveform of the CDS 102, and has a OB pixel output for a predetermined period for each horizontal line read from the image sensor 101, and a timing signal for sample-holding a part of this OB pixel output period. Is the OB clamp pulse 20D.

  The OB pixel output of the signal waveform 20A is maintained at a DC voltage that is relatively close to the reference voltage VREF by the action of the CDS (correlated double sampling) circuit 102. A difference component (CCD offset) from the signal component and a dark current component depending on the temperature of the image sensor are superimposed to have an offset error (usually several millimeters to several tens of millivolts).

  This offset error varies for each image sensor, and varies depending on the temperature. Then, this offset error is amplified by the variable amplifier 104 and finally outputted as the black level fluctuation VERR of the imaging signal.

  The black level fluctuation VERR is detected as a difference of the VREF voltage by the sample hold circuit 107 and the integrating amplifier 105, integrated and output as the integrated output signal 20B shown in FIG. 2, and the deviation amount of the output 20B from the voltage VREF is Subtracted from the output signal 20A of the CDS circuit 102.

  By repeating this operation for each output of the OB clamp pulse 20D, the integration output 20B and the OB pixel output of the output signal of the variable amplifier 104 converge to the reference voltage VREF as in the signal waveform 20C.

  The above is the clamping operation for keeping the black reference of the image at a constant value in a video camera or the like.

As another conventional example, for example, Patent Document 1 and Patent Document 2 can be cited.
Japanese Patent Laid-Open No. 10-332684 Japanese Patent Laid-Open No. 09-18791

  By the way, when a strong light such as direct sunlight is incident on a solid-state device such as a CCD, a phenomenon called so-called blooming occurs in which the electric charge overflows in the photoelectric conversion unit. When blooming occurs, the overflowed charge may flow into and accumulate in the OB pixel portion that is originally shielded in the light receiving pixel portion and does not depend on incident light. This causes an abnormal level in the OB part.

  In this case, unlike the offset error component, the OB level cannot be an accurate black reference, but also reaches a full range level change (CCD saturation level VSAT) of the imaging signal for intense blooming.

  FIG. 3 shows operation waveforms of respective parts for explaining the clamping operation when blooming occurs. The OB output of the CDS output 30A rapidly reaches the CCD saturation level VSAT as blooming occurs. The OB output of the PGA output 30C is gradually lowered to the reference voltage VREF with respect to the erroneous OB level that has risen to the CCD saturation level VSAT with a response time based on the time constant set by the integrating amplifier 105.

  As described above, in the conventional clamp circuit configuration, when blooming occurs, an incorrect black level that greatly deviates from an appropriate OB level is followed, and the entire imaging signal is darkened.

  Also, as a result of following an erroneous black level that greatly deviates from the appropriate OB level, it takes a very long time to return to the normal OB level even after the blooming of the image sensor has been resolved. Will continue. As a result, in the case of a multi-field readout sensor, the head portion of the first field becomes an image in which blackening has occurred without returning to the OB level.

  As described above, an imaging device such as a video camera has a problem that an image having an abnormal first field is formed.

  On the other hand, the present invention has three operation modes: a method for detecting an abnormal OB level in the image pickup apparatus according to claim 1, an image capturing prohibition, an abnormal image capturing, and an abnormal image correction. The present invention provides a method for selecting and correcting abnormal images.

  The present invention relates to an image forming means for optically forming a subject on an image pickup device, an interline type image pickup device that converts an optical image of the subject into an electric signal and forms one frame signal by reading a plurality of fields, and an optical device. In an imaging apparatus having a DC component reproducing unit that adjusts a target black level to a predetermined reference level, when image processing is performed on an electrical signal read from the imaging element, a first field of one frame signal formed by the imaging element Means for detecting an image abnormality, and when the first field of one frame signal formed by the image sensor in the imaging device is determined to be an image abnormality, warning means for the occurrence of an image abnormality, and the detection means in the imaging device. As a result, when it is determined that the first field of one frame signal formed by the image sensor is abnormal, the image signals after the second field It relates an imaging apparatus characterized by having a means for correcting one frame image using.

  Further, in this imaging apparatus, when the imaging device captures an image of a subject and performs image processing, a portion that is shielded and is not exposed to light is used as an optical black reference of an image signal. This standard is called OB. The image abnormality detection means detects an amount of deviation between the OB level of the image sensor and the absolute OB target value. Alternatively, a correlation between the OB level of the first field and the OB level of the second and subsequent fields of one frame signal formed by the image sensor is taken and detected from the amount of deviation.

  Further, the warning means includes any one of operation means for prohibiting recording of a photographed image, recording of an abnormal image, and recording of a corrected image based on an operation mode set in advance in the imaging apparatus.

  The image correcting means corrects a one-frame image of an abnormal portion of the first field of the one-frame signal formed by the image sensor using the image signals of the second and subsequent fields. Alternatively, all the first fields correct one frame image using image signals from the second field.

  Further, when it is determined that the first field of one frame signal formed by the image sensor is abnormal in image, the image correcting unit determines the abnormal portion in the first field as the image signal in the second field and thereafter according to the number of abnormal lines. Are used to switch between correction for correcting one frame image and correction for correcting one frame image using the image signals of the second and subsequent fields.

[Action]
The operation of the above means will be described. When imaging with the above imaging device, strong light such as direct sunlight is incident, electric charge overflows to the OB part of the imaging device, and when the clamping operation does not work normally (blooming occurs), the clamping operation returns to normal. It is assumed that a portion where the image sinks black appears at the signal level of the first field. In addition, since the normal clamping operation has been restored after the second field, a predetermined absolute level of the OB portion is set as a target value, and the difference from the OB portion of the first field is taken and clamped by the value. Whether the operation is normal or not can be detected. Set the difference value to an appropriate value. Alternatively, whether or not the clamping operation is normal can be similarly detected by taking the difference between the OB portion of the first field and the OB portion of the second field and thereafter.

  Used when the user can select three types of recording prohibition, abnormal image recording, and correction image recording based on the operation mode set in the imaging device in advance when an abnormal level of the OB unit can be detected. Appropriate choices can be selected based on the situation and conditions when the person has taken the image. For example, a photographed image that cannot be taken twice is corrected and recorded. The user can have a range of selection.

  When an abnormality at the OB portion level in the first field is detected and the captured image is corrected, there are two image correction means, one of which uses only the abnormal portion of the first field as one frame by using the image signal from the second field. Correct the image. If the abnormal lines in the first field are several lines, it is possible to construct an image with minimal correction by correcting only the lines in which abnormalities are found and using the normal lines as they are as captured images.

  The other is that in the first field, one frame image is corrected using the image signals from the second field onward. If the abnormal portion of the first field occupies more than half of all lines, an image without any sense of incongruity can be formed when the entire first frame is viewed when all the first fields are corrected. When image correction is selected, the above two image correction means can be switched, so that the user can have a range of selection.

  Further, for example, if the image pickup device uses a three-field readout CCD or the like, there are two portions of data used for correction, and the portion of data to be corrected is one field, so that the roughness of the corrected image becomes inconspicuous. In consideration, the effect of the present invention can be sufficiently obtained for a multi-field reading sensor, and the image correcting means is considered to be effective.

  As described above, according to the present invention, when electric charge overflows to the OB portion of the image sensor and the clamp operation does not work normally (blooming occurs), it is possible to detect whether the clamp operation is normal or not. Based on an operation mode set in advance in the imaging apparatus, three selections can be made: recording prohibition of captured images, recording of abnormal images, and recording of corrected images. Appropriate selection can be made in consideration of the conditions at the time of shooting by the user. Even when the image is corrected, a sense of incongruity when the image is corrected can be reduced by using a plurality of field sensors having three or more fields.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings. FIG. 4 shows the overall configuration of the image pickup apparatus used in the embodiment of the present invention. First, the imaging device will be described. In FIG. 4, 100 is an overall view of the image processing apparatus. Reference numeral 12 denotes a shutter for controlling the exposure amount to the imaging unit 14, and reference numeral 14 denotes an imaging unit that converts an optical image into an electrical signal.

  The light beam incident on the lens 310 can be guided through the diaphragm 312, the lens mounts 306 and 106, the mirror 130, and the shutter 12 by the single lens reflex method, and can be formed on the imaging unit 14 as an optical image.

  Reference numeral 16 denotes an A / D conversion unit that converts an analog signal output from the imaging unit 14 into a digital signal. Reference numeral 18 denotes a timing generation circuit that supplies a clock signal and a control signal to the imaging unit 14, the A / D conversion unit 16, and the D / A converter 26, and is controlled by the memory control circuit 22 and the system control circuit 50.

  An image processing circuit 20 performs predetermined pixel interpolation processing and color conversion processing on the data from the A / D converter 16 or the data from the memory control circuit 22. In the image processing circuit 20, a predetermined calculation process is performed using the captured image data as necessary, and the system control circuit 50 performs exposure control means 40 and distance measurement control means based on the obtained calculation result. TTL (through-the-lens) AF (autofocus) processing, AE (automatic exposure) processing, and EF (flash light control) processing can be performed.

  Further, the image processing circuit 20 performs predetermined arithmetic processing using the captured image data, and also performs TTL AWB (auto white balance) processing based on the obtained arithmetic result.

  Reference numeral 22 denotes a memory control circuit that controls the A / D conversion unit 16, the timing generation circuit 18, the image processing circuit 20, the image display memory 24, the D / A converter 26, the memory 30, and the compression / decompression circuit 32.

  The data of the A / D converter 16 is written into the image display memory 24 or the memory 30 via the image processing circuit 20 and the memory control circuit 22 or the data of the A / D converter 16 is directly passed through the memory control circuit 22. It is.

  Reference numeral 24 denotes an image display memory, 26 denotes a D / A converter, and 28 denotes an image display unit composed of a TFT LCD or the like. Display image data written in the image display memory 24 passes through the D / A converter 26. Displayed by the image display unit 28.

  If the image data captured using the image display unit 28 is sequentially displayed, the electronic viewfinder function can be realized. Further, the image display unit 28 can arbitrarily turn on / off the display according to an instruction from the system control circuit 50. When the display is turned off, the power consumption of the image processing apparatus 100 can be greatly reduced. I can do it.

  Reference numeral 30 denotes a memory for storing captured still images and moving images, and has a sufficient storage capacity to store a predetermined number of still images and a predetermined time of moving images. Thereby, even in the case of continuous shooting or panoramic shooting in which a plurality of still images are continuously shot, it is possible to write a large amount of images to the memory 30 at high speed. The memory 30 can also be used as a work area for the system control circuit 50.

  Reference numeral 32 denotes a compression / decompression circuit that compresses and decompresses image data by adaptive discrete cosine transform (ADCT) or the like, reads an image stored in the memory 30, performs compression processing or decompression processing, and stores the processed data in the memory 30. Write to.

  Reference numeral 40 denotes shutter control means for controlling the shutter 12 in cooperation with the aperture control means 340 for controlling the aperture 312 based on photometric information from the photometry means 46.

  Reference numeral 42 denotes distance measuring means for performing AF (autofocus) processing. Light beams incident on the lens 310 are converted into an aperture 312, lens mounts 306 and 106, a mirror 130, and a distance measuring sub mirror (not shown) by a single-lens reflex system. , The in-focus state of the image formed as an optical image can be measured.

  Reference numeral 46 denotes photometric means for performing AE (automatic exposure) processing. Light rays that have entered the lens 310 are converted into an aperture 312, lens mounts 306 and 106, mirrors 130 and 132, and a photometric lens (not shown) by a single-lens reflex system. Then, the exposure state of the image formed as an optical image can be measured.

  The photometry means 46 also has an EF (flash dimming) processing function in cooperation with the flash 48. A flash 48 has an AF auxiliary light projecting function and a flash light control function.

  The system control circuit 50 controls the shutter control unit 40, the aperture control unit 340, and the distance measurement control unit 342 based on the calculation result obtained by calculating the image data captured by the imaging unit 14 by the image processing circuit 20. It is also possible to perform exposure control and AF (autofocus) control using the video TTL method.

  Further, AF (autofocus) control may be performed using both the measurement result by the distance measuring means 42 and the calculation result obtained by calculating the image data captured by the imaging unit 14 by the image processing circuit 20.

  The exposure control may be performed using both the measurement result obtained by the photometry unit 46 and the calculation result obtained by calculating the image data captured by the imaging unit 14 by the image processing circuit 20.

  Reference numeral 50 denotes a system control circuit that controls the entire image processing apparatus 100, and reference numeral 52 denotes a memory that stores constants, variables, programs, and the like for operation of the system control circuit 50. Reference numeral 54 denotes a display unit such as a liquid crystal display device or a speaker that displays an operation state or a message using characters, images, sounds, or the like in accordance with execution of a program in the system control circuit 50. One or a plurality of places are provided near the portion where they can be easily seen, and for example, a combination of an LCD, an LED, a sound generation element, and the like is used.

  In addition, the display unit 54 is partially installed in the optical viewfinder 104. Among the display contents of the display unit 54, what is displayed on the LCD etc. is, for example, single shot / continuous shooting display, self-timer display, compression rate display, number of recorded pixels, number of recorded images, number of remaining images that can be captured , Shutter speed display, Aperture value display, Exposure compensation display, Flash display, Red-eye reduction display, Macro shooting display, Buzzer setting display, Clock battery level display, Battery level display, Error display, Multi-digit number information display , Attachment / detachment state display of the recording media 200 and 210, attachment / detachment state display of the lens unit 300, communication I / F operation display, date / time display, display showing a connection state with an external computer, and the like.

  In addition, among the display contents of the display unit 54, what is displayed in the optical viewfinder 104 is, for example, in-focus display, shooting preparation completion display, camera shake warning display, flash charge display, flash charge completion display, shutter speed display, There are an aperture value display, an exposure correction display, a recording medium writing operation display, and the like.

  Further, among the display contents of the display unit 54, what is displayed on the LED or the like includes, for example, in-focus display, shooting preparation completion display, camera shake warning display, camera shake warning display, flash charge display, flash charge completion display, recording medium There are a writing operation display, a macro shooting setting notification display, a secondary battery charge state display, and the like.

  And what is displayed on a lamp etc. among the display contents of the display part 54 includes a self-timer notification lamp, for example. This self-timer notification lamp may be used in common with AF auxiliary light.

  Reference numeral 56 denotes an electrically erasable / recordable nonvolatile memory, such as an EEPROM. Reference numerals 60, 62, 64, 66, 68 and 70 are operation means for inputting various operation instructions of the system control circuit 50, and may be a single unit such as a switch, a dial, a touch panel, pointing by line-of-sight detection, a voice recognition device, or the like. Consists of multiple combinations.

  Reference numeral 72 denotes a power switch, which can switch and set the power-on and power-off modes of the image processing apparatus 100. Also, the power on and power off settings of various accessory devices such as the lens unit 300, the external strobe, and the recording media 200 and 210 connected to the image processing apparatus 100 can be switched.

  Reference numeral 74 denotes a real time clock circuit, whereby the system control circuit 50 measures the elapsed time and realizes various timer functions.

  80 is a power control means, which is composed of a battery detection circuit, a DC-DC converter, a switch circuit for switching a block to be energized, etc., and detects the presence / absence of a battery, the type of battery, the remaining battery level, and the detection result In addition, the DC-DC converter is controlled based on an instruction from the system control circuit 50, and a necessary voltage is supplied to each part including the recording medium for a necessary period.

  Reference numeral 82 denotes a connector, 84 denotes a connector, and 86 denotes a power source means including a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a NiCd battery, a NiMH battery, or a Li battery, or an AC adapter.

  90 and 94 are interfaces with a recording medium such as a memory card or a hard disk, 92 and 96 are connectors for connecting to a recording medium such as a memory card or a hard disk, and 98 is a recording medium 200 or 210 attached to the connector 92 and / or 96. It is a recording medium attachment / detachment detecting means for detecting whether or not the recording medium is being used. A single or a plurality of interfaces and connectors for attaching the recording medium may be provided. Moreover, it is good also as a structure provided with combining the interface and connector of a different standard.

  The interface and the connector may be configured using a standard-compliant one.

  When the interfaces 90 and 94 and the connectors 92 and 96 are configured in accordance with the standards, various types of communication cards such as LAN cards, modem cards, USB cards, IEEE1394 cards, P1284 cards, SCSI cards, PHS, etc. By connecting the communication card, image data and management information attached to the image data can be transferred to and from other computers and peripheral devices such as a printer.

  Reference numeral 104 denotes an optical viewfinder, which can guide and display a light beam incident on the lens 310 through an aperture 312, lens mounts 306 and 106, and mirrors 130 and 132 as an optical image by a single lens reflex system. Accordingly, it is possible to perform shooting using only the optical viewfinder 104 without using the electronic viewfinder function of the image display unit 28. In the optical viewfinder 104, some functions of the display unit 54, for example, a focus display, a camera shake warning display, a flash charge display, a shutter speed display, an aperture value display, an exposure correction display, and the like are installed.

  A communication unit 110 has various communication functions such as RS232C, USB, IEEE1394, P1284, SCSI, modem, LAN, and wireless communication.

  Reference numeral 112 denotes a connector for connecting the image processing apparatus 100 to another device by the communication unit 110 or an antenna in the case of wireless communication.

  Reference numeral 120 denotes an interface for connecting the image processing apparatus 100 to the lens unit 300 in the lens mount 106, 122 denotes a connector for electrically connecting the image processing apparatus 100 to the lens unit 300, and 124 denotes the lens mount 106 and / or the connector. Reference numeral 122 denotes lens attachment / detachment detection means for detecting whether or not the lens unit 300 is attached.

  The connector 122 communicates control signals, status signals, data signals, and the like between the image processing apparatus 100 and the lens unit 300, and also has a function of supplying currents of various voltages. The connector 122 may be configured to transmit not only electrical communication but also optical communication, voice communication, and the like.

  Reference numerals 130 and 132 denote mirrors that can guide the light beam incident on the lens 310 to the optical viewfinder 104 by a single-lens reflex system. The mirror 132 may be either a quick return mirror or a half mirror.

  Reference numeral 200 denotes a recording medium such as a memory card or a hard disk. The recording medium 200 includes a recording unit 202 composed of a semiconductor memory, a magnetic disk, or the like, an interface 204 with the image processing apparatus 100, and a connector 206 for connecting to the image processing apparatus 100.

  Reference numeral 210 denotes a recording medium such as a memory card or a hard disk. The recording medium 210 includes a recording unit 212 composed of a semiconductor memory, a magnetic disk, and the like, an interface 214 with the image processing apparatus 100, and a connector 216 that connects to the image processing apparatus 100.

  Reference numeral 300 denotes an interchangeable lens type lens unit. Reference numeral 306 denotes a lens mount that mechanically couples the lens unit 300 to the image processing apparatus 100. The lens mount 306 includes various functions for electrically connecting the lens unit 300 to the image processing apparatus 100.

  Reference numeral 310 denotes a photographing lens, and 312 denotes an aperture. Reference numeral 320 denotes an interface for connecting the lens unit 300 to the image processing apparatus 100 in the lens mount 306, and reference numeral 322 denotes a connector for electrically connecting the lens unit 300 to the image processing apparatus 100.

  The connector 322 transmits a control signal, a status signal, a data signal, and the like between the image processing apparatus 100 and the lens unit 300, and also has a function of supplying or supplying currents of various voltages. The connector 322 may be configured to transmit not only electrical communication but also optical communication, voice communication, and the like.

  Reference numeral 340 denotes an aperture control unit that controls the aperture 312 in cooperation with the shutter control unit 40 that controls the shutter 12 based on photometric information from the photometry unit 46.

  Reference numeral 342 denotes distance measurement control means for controlling the focusing of the photographing lens 310, and reference numeral 344 denotes zoom control means for controlling zooming of the photographing lens 310.

  A lens system control circuit 350 controls the entire lens unit 300. The lens system control circuit 350 includes a memory for storing operation constants, variables, programs and the like, identification information such as a number unique to the lens unit 300, management information, function information such as an open aperture value, a minimum aperture value, a focal length, It also has a non-volatile memory function for holding current and past set values.

  The above is the outline of the imaging apparatus used in the embodiment of the present invention.

  The specific principle of the present invention using the above-described imaging apparatus will be described with reference to FIGS. 1, 3, 4, 5, 6, 7, and 8. FIG. 1 can be applied to the imaging unit 14 of FIG. 4 with the circuit block used in the section of the prior art. The image sensor of the imaging unit 14 uses a three-field readout CCD. FIG. 5 shows the frame readout timing of the CCD when strong light such as direct sunlight is incident on the OB portion of the 3-field readout CCD. FIG. 6 is a flowchart of the operation performed when the OB level abnormality is detected by the imaging apparatus when strong light is incident on the OB portion. FIG. 7 describes the principle for detecting an OB level abnormality. FIG. 8 is a principle diagram of the image correcting means when an OB level abnormality is detected by the detecting means and image correction is selected. Details of the figure will be described in the following description.

First Embodiment Photographing (S601 in FIG. 6) is performed by the imaging apparatus. Strong light such as direct sunlight is incident on the photographing lens (310 in FIG. 4), and the shutter (12 in FIG. 4) is closed by shutter control (40 in FIG. 4). Then, the CCD output appears at the imaging unit (14 in FIG. 4). In other words, after the mechanical shutter is closed (502) in FIG. 5, the CCD output (503) is determined for each field in the imaging unit by the vertical synchronization signal VD (501).

  On the other hand, the overflowed charge also flows into and accumulates in the OB pixel portion which is shielded from light in the light receiving pixel portion and does not depend on the incident light, causing a level abnormality in the OB portion. Although detailed description is omitted because it has been described in the section of the problem to be solved by the invention (see FIG. 3), the output of the OB portion in the CDS output rapidly reaches the CCD saturation level as blooming occurs. The output of the OB portion in the PGA output is gradually lowered to the reference voltage with respect to the erroneous OB level that has risen to the CCD saturation level with the response time based on the time constant set by the integration amplifier. Then, the wrong OB level is used as the black reference of the image, and after analog / digital conversion (16 in FIG. 4), the signal processing circuit for image processing (20 in FIG. 4) is entered.

  Here, the abnormal image detection means (S602 in FIG. 6) will be described. When the A / D resolution is 10 bits, the minimum unit when the above resolution is applied to the saturation voltage of the three-field readout is 1 LSB. In the case of the above resolution, the saturation voltage is 1024 LSB. Further, it is assumed that one frame is configured for the CCD as shown in FIG. FIG. 7-B is an internal block diagram of the memory for storing digital data after A / D conversion.

  When digital data is stored for each line in each field, based on the control of the system control (50 in FIG. 4), the OB pixel average data S7C0 in the first field and a predetermined value are shown in FIG. 7-C. The difference is successively taken line by line with the absolute target value S7C1 of the OB level set to the value of. The absolute target value of the OB level is the ideal black reference voltage amplitude of the PGA output (104 in FIG. 1). If a signal waveform is formed around 32 LSB, this value of 32 LSB is set as the OB target in FIG. It shall be set to the value S7C1. Although the number of OB pixels is defined by the type of the CCD, it is possible to determine how many OB pixels are used for obtaining OB pixel average data. Needless to say, it is possible to more accurately determine whether or not the OB level is abnormal when there are more average OB pixels. In addition, the determination for the calculation result can determine how much deviation from the ideal black reference is an OB level abnormality. For example, if the threshold of the calculation result is set to 5 LSB, If the absolute value exceeds 5 LSB, it is determined that the OB level of the line is abnormal (S7C3), and the number of the line is written in the memory S7C6. After performing the above calculation for all lines, if there is a line whose absolute value of the calculation result exceeds 5 LSB, that is, if the OB level of one line is deviated from 5 LSB in the voltage direction from the target value (S603 in FIG. 6) Move to operation. When the warning operation is started, the branch is made with the value of the counter (S7C7). This counter value is the number of abnormal lines written in the memory (S7C6), and there is an abnormal line even with one line. The above warning operation is started. In accordance with the number of pixels of the CCD (the number of lines constituting one frame), the above calculation is performed on all effective pixel lines in the first field in a combination having the regularity as described above, and the process proceeds to development (S607 in FIG. 6). Move on.

  If the state is a warning (S603 in FIG. 6), the operator is warned on the display (54 in FIG. 4) via the system control (50 in FIG. 4). When the warning screen is displayed, the operator stops shooting (S605 in FIG. 6), abnormal image recording (S604 in FIG. 6), and image correction based on the operation mode set by the mode dial (60 in FIG. 4). Any of the operations (S606 in FIG. 6) can be selected. When the photographing stop (S605 in FIG. 6) is selected by the operation unit (70 in FIG. 4), the image processing is not performed and the process returns to the standby state. When recording of an abnormal image (S604 in FIG. 6) is selected, the process proceeds to development (S607 in FIG. 6).

  A description will be given when image correction (S606 in FIG. 6) is selected. As a result of the detection means, the timing of the image signal in the state of moving to the warning operation can be shown in FIG. As described above, the effective pixel timing of each field is determined by the vertical synchronization signal VD (501 in FIG. 5). When moving to the above warning operation, the clamping operation is not performed normally and the screen is darkened. Therefore, an abnormal image portion appears in the first field in the clamp output (504 in FIG. 5). That is, the abnormal image portion in FIG. 5 is a line where the calculation result exceeds 5 LSB.

  There are two types of image correction means in the present invention. First, the first means will be described.

  FIG. 8 shows the state of FIG. 5 configured by one frame screen. FIG. 8A shows a one-frame configuration of a three-field readout CCD sensor. FIG. 8D shows a frame reading method of a three-field reading CCD sensor. In the case of a three-field readout CCD, there are four R, G, G, and B pixels in each field. Accordingly, when an abnormal image portion exists in the first field as shown in FIG. 8A, the third field immediately above and the second field immediately below each color pixel in the abnormal first field as shown in FIGS. 8-B and 8-E. Each color pixel average of the field is taken and corrected as image data in correspondence with each R, G, G, B of the first field. The portion to be corrected is only for the abnormal portion of the first field. When the correction is completed, the process proceeds to development (S607 in FIG. 6).

  Next, the second means will be described. Similarly to the first means, when there is an abnormal portion of the first field, each color of the third field immediately above and the second field immediately below the color pixels of the abnormal first field as shown in FIGS. The pixel average is used to correct the image data corresponding to each of R, G, G, and B in the first field. As for the portion to be corrected, not only the abnormal portion of the first field but also the normal portion is corrected using the second field immediately below. When the correction is completed, the process proceeds to development (S607 in FIG. 6).

  Here, a method for switching the image correction means will be described. As shown in FIG. 7-C, all the lines in the first field are compared with the OB target value when the OB level abnormality is detected. After that, if the difference value as the calculation result is larger than 5 LSB, the number of lines is sequentially written in the memory S7C6 so that the abnormal line can be specified. Therefore, it is possible to detect how many lines are abnormal among all the lines. Therefore, a predetermined value (indicating the number of lines) is set in advance, and the image correction means can be selected by that value. As an effect, if there are several abnormal lines in the first field, only the lines in which an abnormality is found are corrected, and if normal lines are used as they are as captured images, an image with minimal correction can be constructed. The other is that when the abnormal portion of the first field occupies more than half of all the lines, if all the first field is corrected and the entire frame is viewed, an uncomfortable image can be formed. In the above case, for example, two image correction means can be utilized by setting a predetermined value to half of all lines.

  When normal images and abnormal images are recorded and corrected according to the result of the detection means, after development (S607 in FIG. 6), compression / expansion (S608 in FIG. 6) is performed, and recording starts (FIG. 6). S609).

  The above is the first embodiment. However, elements that are not particularly described in this embodiment in the entire block of the imaging apparatus in FIG. 4 are assumed to be performed appropriately among the operations of the elements described above.

By the way, in the first embodiment, the abnormal image detection means (S602 in FIG. 6) uses the OB pixel average data S7C0 of the first field and the absolute target value S7C1 of the OB level set to a predetermined value. It is realized by taking the difference using and. However, it is possible that the OB level in the first field is abnormal but normal after the second field. At this time, there is no problem even if the OB level after the second field is used without using the absolute target value S7C1 of the OB level. This is the third embodiment. Note that FIG. 4 is used as the imaging apparatus. The difference from the first embodiment is an OB level abnormality detection method and image correction switching means. The image correction method may be the first embodiment. Hereinafter, the second OB level abnormality detection method will be described with reference to the drawings.

  The abnormal image second detection means (S602 in FIG. 6) will be described. FIG. 7A shows a frame configuration when a CCD with three-field readout is used as an imaging device in the imaging apparatus and an image is taken. FIG. 7-B is an internal block diagram of the memory for storing digital data after A / D conversion.

  When the digital data is stored for each line in each field, based on the control of the system control (50 in FIG. 4), the OB pixel average data S7D0 in the first field and the first data as shown in FIG. Differences are sequentially taken from the OB pixel average data S7D1 of two fields. Although the number of OB pixels is defined by the type of the CCD, it is possible to determine how many OB pixels are used for obtaining OB pixel average data. Needless to say, it is possible to more accurately determine whether or not the OB level is abnormal when there are more average OB pixels. In addition, the determination on the calculation result can determine how much deviation from the OB level of the second field is an abnormality of the OB level of the first field. For example, the threshold of the calculation result is set to 5 LSB. If set, if the absolute value of the calculation result exceeds 5 LSB, it is determined that the OB level of the line is abnormal (S7D6), and the number of the first field in the line is written in the memory S7D8. For the above calculation, if there is a line whose absolute value of the calculation result exceeds 5 LSB, that is, even if the OB level is deviated from 5 LSB in the voltage direction from the OB level of the second field even in one line, a warning (S603 in FIG. 6) operation is performed. Move. When the warning operation is started, the branch is made with the value of the counter (S7D9), but this counter value is the number of abnormal lines written in the memory (S7D8), and there is an abnormal line even with one line. The above warning operation is started. In accordance with the number of pixels of the CCD (the number of lines constituting one frame), the above calculation is performed on all effective pixel lines in the first field in a combination having the regularity as described above, and the process proceeds to development (S607 in FIG. 6). Move on.

  In addition, the correction method when the warning operation is selected and the image correction is selected is the same as in the first embodiment, and there are two correction methods.

  Here, a method for switching the image correction means will be described. As shown in FIG. 7D, all lines in the first field are compared with the OB values in the second field when the OB level abnormality is detected. After that, if the difference value as the calculation result is larger than 5 LSB, the number of lines in the first field is sequentially written in the memory S7D8 so that the abnormal line can be specified. Therefore, it is possible to detect how many lines are abnormal among all the lines. Therefore, a predetermined value (indicating the number of lines) is set in advance, and the image correction means can be selected by that value. As an effect, if there are several abnormal lines in the first field, only the lines in which an abnormality is found are corrected, and if normal lines are used as they are as captured images, an image with minimal correction can be constructed. The other is that when the abnormal portion of the first field occupies more than half of all the lines, if all the first field is corrected and the entire frame is viewed, an uncomfortable image can be formed. In the above case, for example, two image correction means can be utilized by setting a predetermined value to half of all lines.

  When normal images and abnormal images are recorded and corrected according to the result of the detection means, after development (S607 in FIG. 6), compression / expansion (S608 in FIG. 6) is performed, and recording starts (FIG. 6). S609).

  However, the operations of the first embodiment described above are performed for operations other than the OB level abnormality detection method and the image correction switching means.

  The above is the second embodiment.

  The above embodiment is merely an example. For example, in the second embodiment, if the OB level is abnormal up to the second field, an application such as taking a difference from the first field based on the OB level of the third field is used. Is also conceivable. Furthermore, as described in claim 1, it is not necessary to limit the CCD to three-field readout in any of the above-described embodiments, and it is naturally included to use more field readout sensors. In the first place, it is not necessary to limit to CCD.

It is a block diagram of the prior art and all the embodiments of the present invention. This is an operation waveform when no problem occurs. It is an operation waveform when a problem occurs. 1 is an overall configuration block diagram according to all embodiments of the present invention. It is an operation waveform when a problem occurs. 3 is a flowchart according to all embodiments of the present invention. It is the block diagram and flowchart which concern on all the Examples of this invention. It is a block diagram concerning all the examples of the present invention.

Explanation of symbols

101 CCD
102 CDS
103 Offset addition circuit 104 Variable amplifier 105 Integration amplifier 106 Reference voltage VREF
107 Sample Hold Circuit 108 Image Processing / Recording / Display Circuit 109 OB Clamp Pulse 2 Shutter 14 Imaging Unit 1
DESCRIPTION OF SYMBOLS 16 A / D conversion part 18 Timing generation circuit 20 Image processing circuit 22 Memory control circuit 24 Image display memory 26 D / A converter 28 Image display part 30 Memory 32 Image compression / decompression circuit 40 Shutter control means 42 Distance measurement means 46 Photometry Means 48 Flash 50 System control circuit 52 Memory 54 Display unit 56 Non-volatile memory 60 Mode dial switch 62 Shutter switch SW1
64 Shutter switch SW2
66 Playback Switch 68 Single / Continuous Shooting Switch 70 Operation Unit 72 Power Switch 74 Real Time Clock 80 Power Supply Control Unit 82 Connector 84 Connector 86 Power Supply Unit 90 Interface 92 Connector 94 Interface 96 Connector 98 Recording Medium Attachment / Disconnection Detection Unit 100 Image Processing Device 104 Optical Finder 106 Lens mount 110 Communication means 112 Connector (or antenna)
DESCRIPTION OF SYMBOLS 120 Interface 122 Connector 130 Mirror 132 Mirror 200 Recording medium 202 Recording part 204 Interface 206 Connector 210 Recording medium 212 Recording part 214 Interface 216 Connector 300 Lens unit 306 Lens mount 310 Shooting lens 312 Aperture 320 Interface 322 Connector 340 Exposure control means 342 Distance measurement Control unit 344 Zoom control unit 350 Lens system control circuit

Claims (5)

Imaging means for optically imaging a subject on the imaging device, an interline imaging device that converts an optical image of the subject into an electrical signal and forms one frame signal by reading a plurality of fields, and an optical black level In an imaging apparatus having a direct current component reproducing means for adjusting the frequency to a predetermined reference level,
Means for detecting an image abnormality in the first field of one frame signal formed by the image sensor when image processing is performed on the electrical signal read from the image sensor;
In the imaging apparatus, when it is determined that the first field of one frame signal formed by the imaging element is an image abnormality, warning means for occurrence of an image abnormality
Means for correcting one frame image using the image signals of the second and subsequent fields when the first field of the one frame signal formed by the image sensor is determined to be an image abnormality as a result of the detection means in the imaging device; ,
An imaging device comprising:   2. The image pickup apparatus according to claim 1, wherein the image pickup device uses a portion that is shielded from light and does not receive light as an optical black reference of an image signal when an object is picked up and image-processed. This standard is called OB (Optical Black, hereinafter referred to as OB). The image abnormality detection means according to claim 1 detects a deviation amount between the OB level of the image sensor and the absolute OB target value. Alternatively, the correlation is made between the OB level of the first field of the one-frame signal formed by the image sensor and the OB levels of the second and subsequent fields, and the deviation is detected.   According to a first aspect of the present invention, the warning means includes any one of operation means for prohibiting recording of a captured image, recording of an abnormal image, and recording of a corrected image based on an operation mode set in advance in the imaging apparatus according to the first aspect.   The image correction means according to claim 1 corrects a one-frame image of an abnormal portion of the first field of the one-frame signal formed by the image sensor using the image signals of the second and subsequent fields. Alternatively, one frame image is corrected using image signals from the second field onward in all the first fields.   The image correction means according to claim 1, when it is determined that the first field of one frame signal formed by the image pickup device is abnormal, the abnormal portion of the first field is determined based on the number of abnormal lines. Switching between correction for correcting one frame image using a signal and correction for correcting one frame image using an image signal in the second and subsequent fields in all first fields is switched.

Images