JP4393177B2 - Imaging apparatus and imaging method - Google Patents

Description

  The present invention relates to an imaging apparatus that captures, records, and reproduces still images and moving images, and an imaging apparatus control method.

  2. Description of the Related Art Conventionally, an image processing apparatus such as an electronic camera that records and reproduces a still image or a moving image captured by a solid-state imaging device such as a CCD or CMOS using a memory card having a solid-state memory element as a recording medium is already on the market.

  Many of the image pickup devices of these electronic cameras include a plurality of pixels called OB (Optical Black) pixels shielded from light by an aluminum film or the like, and the output value of the OB pixel range is used as the black level of the image pickup apparatus. There are many imaging devices that perform OB clamping. In addition, the optical black area | region part described in the claim is equivalent to the OB part here.

  Here, the black level adjustment by the OB clamp has the following problems.

  That is, there is a possibility that a so-called OB level difference in which the dark level is different between the OB portion and the effective pixel portion may occur.

  If an OB step occurs, the output signal value in the dark state where there is no incident light is wrong, and the linearity of the output signal with respect to the incident light quantity cannot be maintained. As a result, for example, a problem that the color after the white balance processing becomes strange occurs.

  9 and 10 are diagrams for explaining a problem due to the OB step, and FIG. 9 is a diagram when the output value of the OB portion is larger than that of the effective pixel portion when there is no OB step.

  FIGS. 9A and 10A are examples of output images when the amount of incident light increases from the left to the right in proportion to the distance from the left end. FIGS. 9B and 10B. Is a graph showing an output signal before OB clamping, and FIGS. 9C and 10C are graphs showing an output signal after OB clamping.

  As shown in the graph of FIG. 9 (c), when the OB is an appropriate output as shown in FIG. 9, the output after the OB clamping is kept linear, but an OB step occurs as shown in FIG. In this case, as shown in the graph of FIG. 10 (c), the linearity is not maintained, and the portion where the output is lower than the OB portion is blacked out. In particular, as shown in FIG. 10, when the output value of the OB portion becomes larger than the output value of the effective pixel portion, and the low-luminance area is blacked out by the OB clamp, only the problem that the color becomes strange due to the deterioration of linearity. In addition, there is a lack of information that the output of the portion below the predetermined luminance sticks to 0 (zero), and in this case, the correct image cannot be obtained by the correction after the image is output. End up.

  Many image pickup apparatuses that perform OB clamping have taken various measures to avoid the problem due to the OB step, and the method is to take an image with the image sensor once shielded from light, and the OB portion of the output image. In most cases, the step of the effective pixel portion is obtained and a process is performed to remove the step amount during OB clamping.

As a technique for correcting the OB level difference, for example, in Patent Document 1, an OB level difference is calculated from a luminance signal level of at least two frames exposed at an appropriate exposure time and an exposure time different from the appropriate exposure time. A video signal processing method for correcting at an input stage is disclosed.
JP 2002-354348 A

  However, in the method of dealing with the problem of the OB step in such a conventional solid-state imaging device such as an electronic camera, there are the following problems.

  In other words, in order to remove the adverse effects due to the OB step, a procedure of capturing an image in which incident light is blocked once has to be performed, that is, extra time is taken for imaging.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an imaging apparatus that prevents the deterioration of linearity due to the occurrence of an OB step without increasing the imaging time.

To achieve the above object, an imaging apparatus of the present invention, the optical image exposure with a plurality of pixels for converting into electrical signals, and an image pickup element composed of an effective pixel portion and the optical black region unit, the Detection means for detecting a minimum output value of the entire range or a partial range in the effective pixel portion of the image sensor as an effective pixel portion minimum value, and an average value of output signals of the entire range or a partial range of the optical black region portion The OB integration means for calculating and obtaining the OB integral value is compared with the effective pixel portion minimum value and the OB integration value, and the smaller one of the effective pixel portion minimum value and the OB integration value is determined as black. An imaging apparatus comprising: black level selection means for selecting as a level; and correction means for correcting an output signal of the image sensor with the black level selected by the black level selection means.

The imaging method of the present invention comprises a plurality of pixels, an optical image exposure by the image pickup device composed of an effective pixel portion and the optical black area part converted into an electrical signal, in the effective pixel portion of the imaging element The minimum output value of the entire range or a partial range is detected as the effective pixel portion minimum value, and the average value of the output signals of the entire range or the partial range of the optical black area is calculated to obtain the OB integral value. The effective pixel portion minimum value and the OB integral value are compared, the smaller one of the effective pixel portion minimum value and the OB integral value is selected as a black level, and the output signal of the image sensor is It is characterized by correcting at the black level .

  According to the present invention, it is possible to perform an appropriate black level detection that does not depend on the shooting environment without time loss, and it is possible to provide an imaging device that does not generate an image with blackout or poor linearity.

  The present invention is implemented in the following apparatus, for example.

<Example>
FIG. 1 is a diagram showing a configuration of an embodiment of an imaging apparatus according to the present invention.

  In FIG. 1, reference numeral 100 denotes an image processing apparatus. Reference numeral 12 denotes a shutter for controlling the amount of exposure to the image sensor 14, and reference numeral 14 denotes an image sensor 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 image sensor 14 as an optical image.

  Reference numeral 16 denotes an A / D converter that converts an analog signal output from the image sensor 14 into a digital signal. A timing generation circuit 18 supplies a clock signal and a control signal to the image sensor 14, the A / D converter 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 captured image data, and also performs TTL AWB (auto white balance) processing based on the obtained arithmetic result.

  In addition, the image processing circuit 20 performs predetermined calculation processing using the captured image data, detects the black level of the image according to the present invention based on the obtained calculation result, and sets the black level to zero. The dark clamp processing to make the level is also performed. Predetermined arithmetic processing used for this image processing includes processing for detecting the minimum value of the data in the effective pixel range portion of the image data, and processing for calculating the average value of the predetermined portion of the OB portion data in the image data ( OB integration processing), processing for comparing the minimum value of the effective part calculated by the above two arithmetic processing and the size of the OB integration value, processing for uniformly subtracting the smaller value determined by the comparison from all the image data, etc. There is. Details of this image processing will be described later in the description using the flowcharts of FIGS.

  In this embodiment, since the distance measuring means 42 and the photometry means 46 are provided exclusively, the AF (auto focus) processing, AE (automatic exposure) processing, EF using the distance measuring means 42 and photometry means 46 are used. (Flash dimming) processing may be performed, and AF (auto focus) processing, AE (auto exposure) processing, and EF (flash dimming) processing using the image processing circuit 20 may not be performed. good.

  Alternatively, AF (autofocus) processing, AE (automatic exposure) processing, and EF (flash dimming) processing are performed using the distance measuring means 42 and the photometry means 46, and the image processing circuit 20 is used. An AF (autofocus) process, an AE (automatic exposure) process, and an EF (flash dimming) process may be performed.

  A memory control circuit 22 controls the A / D converter 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, 28 denotes an image display unit including a TFT LCD, and the image data for display 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. 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. This makes it possible to write a large amount of images to the memory 30 at high speed even in continuous shooting or panoramic shooting in which a plurality of still images are continuously shot. 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 a distance measuring means for performing AF (autofocus) processing, and a light beam incident on the lens 310 is 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.

  A thermometer 44 can detect the temperature of the photographing environment. If the thermometer is in the sensor, it is possible to predict the dark current of the sensor more accurately.

  Reference numeral 46 denotes a photometric means for performing AE (automatic exposure) processing, and a light beam incident on the lens 310 is converted into a diaphragm 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 image sensor 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 image sensor 14 by the image processing circuit 20. Then, 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 image sensor 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 are easily visible, and are configured by a combination of, for example, an LCD, an LED, a sound generation element, and the like.

  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 or the like is, for example, single shot / continuous shooting display, self-timer display, compression rate display, ISO sensitivity display, recording pixel number display, recording number display, remaining number display, etc. Number of storable pictures, 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 display There are information display by numbers, 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, photographing 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. The nonvolatile memory 56 stores various parameters, setting values such as ISO sensitivity, setting mode, and correction data used when performing various corrections on a captured image such as OB level difference correction in the present invention. . This correction data is created and written at the time of adjustment in the process, and is created when the power is turned on or when shooting is started. For the OB level difference correction data in the present invention, correction data is created using a photographed image. Therefore, it corresponds to the latter.

  Reference numerals 60, 62, 64, 66, 68, 69 and 70 are operation means for inputting various operation instructions of the system control circuit 50, such as switches, dials, touch panels, pointing by line-of-sight detection, voice recognition devices, and the like. Consists of a single or a plurality of combinations.

  Here, a specific description of these operating means will be given.

  Reference numeral 60 denotes a mode dial switch, which is an automatic shooting mode, program shooting mode, shutter speed priority shooting mode, aperture priority shooting mode, manual shooting mode, depth of focus priority (depth) shooting mode, portrait shooting mode, landscape shooting mode, and close-up shooting. Each function shooting mode such as a mode, a sports shooting mode, a night view shooting mode, and a panorama shooting mode can be switched and set.

  Reference numeral 62 denotes a shutter switch SW1, which is turned on during the operation of a shutter button (not shown), and performs AF (autofocus) processing, AE (automatic exposure) processing, AWB (auto white balance) processing, EF (flash dimming) processing, and the like. Instruct to start operation.

  Reference numeral 64 denotes a shutter switch SW2, which is turned on when the operation of a shutter button (not shown) is completed, and an exposure process for writing a signal read from the image sensor 12 to the memory 30 via the A / D converter 16 and the memory control circuit 22. Development processing using operations in the image processing circuit 20 and the memory control circuit 22, recording processing for reading image data from the memory 30, compression in the compression / decompression circuit 32, and writing the image data to the recording medium 200 or 210. Instructs the start of a series of processing operations.

  Reference numeral 66 denotes a playback switch, which instructs the start of a playback operation in which a shot image is read from the memory 30 or the recording medium 200 or 210 and displayed by the image display unit 28 in the shooting mode state.

  68 is a single-shot / continuous-shooting switch. When the shutter switch SW2 is pressed, a single-shot mode is set in which one frame is shot and the camera is in a standby state, and continuous shooting is performed while the shutter switch SW2 is pressed. You can set the mode.

  Reference numeral 69 denotes an ISO sensitivity setting switch, which can set the ISO sensitivity by changing the gain setting in the image sensor 14 or the image processing circuit 20.

  Reference numeral 70 denotes an operation unit composed of various buttons, a touch panel, and the like. A menu button, a set button, a macro button, a multi-screen playback page break button, a flash setting button, a single shooting / continuous shooting / self-timer switching button, menu movement + (plus) Button, menu shift-(minus) button, playback image shift + (plus) button, playback image-(minus) button, shooting quality selection button, exposure compensation button, date / time setting button, panorama mode shooting and playback Selection / switching button for setting selection and switching of various functions at the time of execution, determination / execution button for setting determination and execution of various functions at the time of executing shooting and playback in panorama mode, etc., ON of the image display unit 28 Image display ON / OFF switch to set / OFF, image data taken immediately after shooting A quick review ON / OFF switch for setting a quick review function for automatic playback, a switch for selecting a compression rate of JPEG compression, or a CCD RAW mode for digitizing an image sensor signal and recording it on a recording medium. If you press the playback switch that can set each function mode such as compression mode switch, playback mode, multi-screen playback / erase mode, PC connection mode, etc. For example, there is an AF mode setting switch that can set a one-shot AF mode that keeps the in-focus state and a servo AF mode that keeps autofocusing continuously while the shutter switch SW1 is pressed.

  In addition, the functions of the plus button and the minus button can be selected more easily by providing a rotary dial switch.

  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 80 denotes a power supply control means, which includes 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 unit including the recording medium for a necessary period.

  Reference numeral 82 denotes a connector, 84 denotes a connector, and 86 denotes 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, an AC adapter, or the like.

  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 or 96. Recording medium attachment / detachment detecting means for detecting whether or not the recording medium is present.

In this embodiment, it is assumed that there are two interfaces and connectors for attaching the recording medium. Of course, the interface and the connector for attaching the recording medium may have a single or a plurality of systems and any number of systems. Moreover, it is good also as a structure provided with combining the interface and connector of a different standard.
The interface and connector may be configured using a PCMCIA card, a CF (Compact Flash (registered trademark)) card, or the like that conforms to a standard.

  Further, when the interfaces 90 and 94 and the connectors 92 and 96 are configured using a PCMCIA card, a CF (Compact Flash (registered trademark)) card, or the like, a LAN card, a modem card, a USB card, IEEE1394. Image data and management information attached to image data are transferred to and from peripheral devices such as other computers and printers by connecting various communication cards such as cards, P1284 cards, SCSI cards, and PHS communication cards. I can meet each other.

  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. As a result, 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.

  120 is an interface for connecting the image processing apparatus 100 to the lens unit 300 in the lens mount 106, 122 is a connector for electrically connecting the image processing apparatus 100 to the lens unit 300, and 124 is 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, or 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 aperture control means for controlling the aperture 312 in cooperation with the shutter control means 40 for controlling the shutter 12 based on photometric information from the photometry means 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 operation of the embodiment of the present invention will be described with reference to FIGS.

  2 and 3 are flowcharts of a main routine of the image processing apparatus 100 according to the embodiment of the present invention. The operation of the image processing apparatus 100 will be described with reference to FIGS.

  Upon power-on such as battery replacement, the system control circuit 50 initializes flags, control variables, and the like, and performs predetermined initial settings necessary for each unit of the image processing apparatus 100 (step S101).

  The system control circuit 50 determines the setting position of the power switch 66, and if the power switch 66 is set to power OFF (step S102), the display on each display unit is changed to the end state, and a flag or control variable is set. Necessary parameters, setting values, and setting modes including the above and the like are recorded in the nonvolatile memory 56, and a predetermined end process such as cutting off unnecessary power sources of the respective units of the image processing apparatus 100 including the image display unit 28 by the power control unit 80. After performing (step S103), it returns to step S102.

  If the power switch 66 is set to ON (step S102), the system control circuit 50 indicates that the remaining capacity and operation status of the power source 86 constituted by a battery or the like by the power source control means 80 is the operation of the image processing apparatus 100. (Step S104). If there is a problem, a predetermined warning is displayed by image or sound using the display unit 54 (step S105), and the process returns to step S102.

  If there is no problem with the power supply 86 (step S104), the system control circuit 50 determines the setting position of the mode dial 60. If the mode dial 60 is set to the photographing mode (step S106), the process proceeds to step S108. .

  If the mode dial 60 has been set to another mode (step S106), the system control circuit 50 executes processing according to the selected mode (step S107), and returns to step S102 when the processing is completed. .

  The system control circuit 50 determines whether or not the recording medium 200 or 210 is mounted, acquires management information of image data recorded on the recording medium 200 or 210, and determines whether the operation state of the recording medium 200 or 210 is image processing. It is determined whether or not there is a problem in the operation of the apparatus 100, in particular, the recording / reproducing operation of the image data with respect to the recording medium (step S108). (Step S105), the process returns to Step S102.

  Determination of whether or not the recording medium 200 or 210 is mounted, acquisition of management information of image data recorded on the recording medium 200 or 210, and the operation state of the recording medium 200 or 210 are the operations of the image processing apparatus 100, particularly As a result of determining whether or not there is a problem in the recording / reproducing operation of the image data with respect to the recording medium (step S108), if there is no problem, the process proceeds to step S109.

  The system control circuit 50 checks the selection state of the single / continuous shooting switch 68 for selecting single shooting / continuous shooting (step S109). If single shooting is selected, the single shooting / continuous shooting flag is set to single shooting (step S110). If continuous shooting is selected, the single shooting / continuous shooting flag is set to continuous shooting (step S110). Step S111). In the single / continuous shooting switch 68, when the shutter switch SW2 is pressed, a single shooting mode in which one frame is shot and the camera is in a standby state, and continuous shooting is performed while the shutter switch SW2 is pressed. It is possible to switch the mode arbitrarily. The state of the single / continuous shooting flag is stored in the internal memory of the system control circuit 50 or the memory 52.

  The system control circuit 50 displays various setting states of the image processing apparatus 100 using images and sounds using the display unit 54 (step S112). If the image display of the image display unit 28 is ON, the image display unit 28 is also used to display various setting states of the image processing apparatus 100 using images and sounds.

  If the shutter switch SW1 has not been pressed (step S121), the process returns to step S102.

  If the shutter switch SW1 is pressed (step S121), the system control circuit 50 performs a distance measurement process to focus the photographing lens 10 on the subject, performs a photometry process, and determines an aperture value and a shutter time. Distance / photometry processing is performed (step S122), and the process proceeds to step S123. In the photometric process, the flash is set if necessary.

  Details of the distance measurement / photometry processing step S122 will be described later with reference to FIG.

  If the shutter switch SW2 has not been pressed (step S123), it is confirmed whether the shutter switch SW1 has been pressed (step S124). If the shutter switch SW1 has been pressed, the process returns to step S123 again. If the shutter switch SW1 has not been pressed (step S124), the process returns to step S102.

  If the shutter switch SW2 is pressed (step S123), the system control circuit 50 determines whether or not the memory 30 has an image storage buffer area capable of storing the captured image data (step S125). If there is no area where new image data can be stored in the image storage buffer area, a predetermined warning is displayed with an image or sound using the display unit 54 (step S126), and the process returns to step S102.

  For example, immediately after performing the maximum number of continuous shots that can be stored in the image storage buffer area of the memory 30, the first image to be read from the memory 30 and written to the storage medium 200 or 210 is still in the recording medium 200 or 210. An example of this state is an unrecorded state where one empty area cannot be secured in the image storage buffer area of the memory 30 yet.

  When the captured image data is compressed and stored in the image storage buffer area of the memory 30, it can be stored in consideration of the fact that the amount of compressed image data varies depending on the compression mode setting. In step S125, it is determined whether the area is on the image storage buffer area of the memory 30.

  If there is an image storage buffer area capable of storing the image data captured in the memory 30 (step S125), the system control circuit 50 reads out an image signal that has been imaged and accumulated for a predetermined time from the image sensor 14, and performs A / D. A photographing process for writing image data photographed in a predetermined area of the memory 30 through the converter 16, the image processing circuit 20, the memory control circuit 22, or directly from the A / D converter through the memory control circuit 22 is executed. (Step S127).

  Details of the photographing process step S127 will be described later with reference to FIG.

  When the photographing process step S127 is completed, the system control circuit 50 reads out part of the data written in the predetermined area of the memory 30 via the memory control circuit 22 and performs WB (required for performing the development process). Pre-development calculation processing such as white balance) integration calculation processing and OB (optical black) integration calculation processing is performed (step S128), and the calculation result is stored in the internal memory or the memory 52 of the system control circuit 50. Details of the pre-development calculation processing step S128 will be described later with reference to FIGS.

  The system control circuit 50 reads the captured image data written in a predetermined area of the memory 30 using the memory control circuit 22 and, if necessary, the image processing circuit 20, and stores the internal memory or memory of the system control circuit 50. Various development processes including an AWB (auto white balance) process, a gamma conversion process, and a color conversion process are performed using the calculation result stored in 52 (step S129).

  Then, the system control circuit 50 reads the image data written in the predetermined area of the memory 30 and performs the image compression processing according to the set mode by the compression / decompression circuit 32 (step S130), and stores the image in the memory 30. Image data that has been photographed and completed a series of processing is written in the empty image portion of the buffer area.

  Along with execution of a series of photographing, the system control circuit 50 reads out the image data stored in the image storage buffer area of the memory 30, and the memory card or compact flash (registration) via the interface 90 or 94 and the connector 92 or 96. A recording process for writing to the recording medium 200 or 210 such as a trademark card is started (step S131).

  This recording start process is performed on the image data every time new image data that has been shot and finished a series of processes is newly written in the empty image portion of the image storage buffer area of the memory 30.

  Note that while writing image data to the recording medium 200 or 210, in order to clearly indicate that the writing operation is being performed, the display unit 54 performs a recording medium writing operation display such as blinking an LED.

  Further, the system control circuit 50 determines whether or not the shutter switch SW1 is pressed (step S132). If the shutter switch SW1 is released, the process returns to step S102. On the other hand, when the shutter switch SW1 is pressed, the state of the single / continuous shooting flag stored in the internal memory of the system control circuit 50 or the memory 52 is determined (step S133), and single shooting is set. If it is, the process returns to step S132, and the current process is repeated until the shutter switch SW1 is released. On the other hand, if continuous shooting has been set, in order to perform continuous shooting, the process returns to step S124 to prepare for the next shooting. As a result, a series of processing relating to photographing is completed.

  FIG. 4 is a detailed flowchart of the distance measurement / photometry process in step S122 of FIG.

  In the distance measurement / photometry processing, the exchange of various signals between the system control circuit 50 and the aperture control means 340 or the distance measurement control means 342 includes interface 120, connector 122, connector 322, interface 320, and lens control means. 350.

  The system control circuit 50 starts an AF (autofocus) process using the image sensor 14 distance measuring means 42 and the distance measuring control means 342 (step S201).

  The system control circuit 50 causes the light beam incident on the lens 310 to enter the distance measuring means 42 through the stop 312, the lens mounts 306 and 106, the mirror 130, and the distance measuring sub mirror (not shown), thereby forming an optical image. The in-focus state of the formed image is determined, and the ranging unit 42 is driven while driving the lens 310 using the ranging control unit 342 until ranging (AF) is determined to be in focus (step S203). AF control is performed to detect the in-focus state using (step S202).

  If ranging (AF) is determined to be in focus (step S203), the system control circuit 50 determines a focused distance point from a plurality of distance measuring points in the shooting screen, and the determined distance measurement. The distance measurement data and / or setting parameters are stored in the internal memory of the system control circuit 50 or the memory 52 together with the point data, and the process proceeds to step S205.

  Subsequently, the system control circuit 50 starts an AE (automatic exposure) process using the photometry means 46 (step S205).

  The system control circuit 50 causes the light beam incident on the lens 310 to enter the photometric means 46 through the stop 312, the lens mounts 306 and 106, the mirrors 130 and 132, and a photometric lens (not shown), thereby forming an optical image. The exposure state of the formed image is measured, and photometric processing is performed using the exposure control means 40 (step S206) until the exposure (AE) is determined to be appropriate (step S206).

  If it is determined that the exposure (AE) is appropriate (step S207), the system control circuit 50 stores the photometric data and / or the setting parameter in the internal memory or the memory 52 of the system control circuit 50, and proceeds to step S208.

  The system control circuit 50 determines the aperture value (Av value) and the shutter speed (Tv value) according to the exposure (AE) result detected in the photometric processing step S206 and the shooting mode set by the mode dial 60. To do.

  Then, in accordance with the shutter speed (Tv value) determined here, the system control circuit 50 determines the charge accumulation time of the image sensor 14 and performs photographing processing with the same charge accumulation time.

  Based on the measurement data obtained in the photometric processing step S206, the system control circuit 50 determines whether or not the flash is necessary (step S208). If the flash is necessary, the flash flag is set and the charging of the flash 48 is completed. (Step S210), the flash 48 is charged (Step S209).

  When the charging of the flash 48 is completed (step S210), the distance measurement / photometry processing routine S122 is terminated.

  FIG. 5 is a detailed flowchart of the photographing process in step S127 of FIG.

  In the photographing process, various signals are exchanged between the system control circuit 50 and the aperture control unit 340 or the distance measurement control unit 342 via the interface 120, the connector 122, the connector 322, the interface 320, and the lens control unit 350. Done.

  The system control circuit 50 moves the mirror 130 to the mirror-up position by a mirror driving unit (not shown) (step S301), and the aperture control unit 340 according to the photometric data stored in the internal memory or the memory 52 of the system control circuit 50. As a result, the aperture 312 is driven to a predetermined aperture value (step S302).

  The system control circuit 50 performs the charge clear operation of the image sensor 14 (step S303), starts the charge accumulation of the image sensor 14 (step S304), and then opens the shutter 12 by the shutter control means 40 (step S305). ), The exposure of the image sensor 14 is started (step S306).

  Here, it is determined whether or not the flash 48 is necessary based on the flash flag (step S307), and if necessary, the flash is emitted (step S308).

  The system control circuit 50 waits for the exposure of the image sensor 14 to end in accordance with the photometric data (step S309), closes the shutter 12 by the shutter control means 40 (step S310), and ends the exposure of the image sensor 14.

  The system control circuit 50 drives the diaphragm 312 to the open diaphragm value by the diaphragm control means 340 (step S311), and moves the mirror 130 to the mirror down position by the mirror driving means (not shown) (step S312).

  If the set charge accumulation time has elapsed (step S313), the system control circuit 50 reads the charge signal from the image sensor 14 after completing the charge accumulation of the image sensor 14 (step S314), and the A / D converter. 16, the captured image data is written to a predetermined area of the memory 30 via the image processing circuit 20, the memory control circuit 22, or directly from the A / D converter 16 via the memory control circuit 22 (step S315). At this time, if it is set to perform pixel addition processing, the charge signal is read after adding the signals of adjacent pixels.

When the series of processing is finished, the photographing processing routine S127 is finished.
(First embodiment)
FIG. 6 is a detailed flowchart for explaining the first embodiment of the pre-development calculation processing in step S128 of FIG.

  The pre-development calculation process in step S128 is performed in the image processing circuit 20. First, the image processing circuit 20 performs WB (white balance) calculation processing using captured image data (step S401).

  Subsequently, the image processing circuit 20 performs OB integration calculation processing for calculating the average of the output values of the OB portion in the captured image data (step S402), and obtains an OB integration value. Next, a pixel having a minimum output value is detected from pixels excluding defective pixels within the effective pixel range in the captured image data, and the output value of the pixel is set as the effective pixel portion minimum value (step S403). .

  Subsequently, the OB integral value obtained in steps S402 and S403 is compared with the value of the effective pixel minimum value (step S404). If the OB integration value is larger than the effective pixel minimum value, the effective pixel minimum value is determined. The captured image data is clamped with the value set to the dark level (step S405). If the minimum value in the effective pixel is larger than the OB integral value in step S404, the captured image data is clamped with the OB integral value as the dark level (step S406).

When the series of processing is finished, the pre-development calculation processing routine S128 is finished. According to such pre-development processing, for example, when the output value of the OB portion is larger than that of the effective pixel portion, the OB integral value is not used as the dark level, and the minimum value within the effective pixel is used as the dark level. The OB step as described with reference to FIG. 10 can be prevented.
(Second embodiment)
FIG. 7 is a detailed flowchart for explaining a second embodiment of the pre-development calculation processing in step S128 of FIG. This is for switching the dark level clamping method in accordance with various shooting modes and shooting conditions.

  The pre-development calculation process in step S128 is performed in the image processing circuit 20 and the system control unit 50.

  First, the image processing circuit 20 performs WB (white balance) calculation processing using captured image data (step S501).

  Subsequently, the image processing circuit 20 performs OB integration calculation processing for calculating the average of the output values of the OB portion in the captured image data (step S502) to obtain an OB integration value.

  Subsequently, the system control unit 50 determines whether or not the mode set by the mode dial 60 is the night view mode (step S503). When the mode dial 60 is the night view mode, the process proceeds to the process of step S504. The process proceeds to step S510. In step S504, the system control unit 50 determines whether or not the ISO sensitivity set by the ISO sensitivity switch 69 is ISO 800 or less. If the set ISO sensitivity is 800 or less, the process proceeds to step S505. In cases other than that described here, process flow proceeds to Step S507. In step S505, the system control unit 50 determines whether or not the ambient temperature output by the thermometer 44 is 30 ° C. or less. When the ambient temperature is 30 ° C. or less, the system control unit 50 proceeds to the process of step S506. Sometimes the process proceeds to step S507. In step S506, the system control unit 50 determines the exposure (AE) result detected in the photometric processing step S206, the shooting mode set by the mode dial 60, the manual setting performed by the user using the operation unit 70 in the manual mode, and the like. It is determined whether or not the determined shutter speed (Tv value) is less than 1 second. If the set Tv value is less than 1 second, the process proceeds to step S510. If it is greater than 1 second, step S507 is performed. Proceed to the process.

  In step S507, the image processing circuit 20 detects a pixel having the minimum output value from the pixels excluding defective pixels in the effective pixel range in the captured image data, and uses the output value of the pixel as an effective pixel unit. Set to the minimum value.

Subsequently, the image processing circuit 20 compares the OB integral value obtained in step S502 and step S507 with the value of the effective pixel minimum value (step S508), and if the OB integration value is larger than the effective pixel minimum value. The captured image data is clamped with the minimum value in the effective pixel set to the dark level (step S509). In step S508, when the effective pixel minimum value is larger than the OB integral value, the process proceeds to step S510.
In step S510, the image data captured with the OB integral value as the dark level is clamped.

  When the series of processing is finished, the pre-development calculation processing routine S128 is finished.

  The second embodiment described with reference to FIG. 7 is a case where a mode with a high possibility of having a dark level range within the effective pixel range, such as a night scene shooting mode, is selected, and a high ISO sensitivity. An appropriate dark level can be obtained even under shooting conditions in which it is difficult to trust the output of the OB portion as a dark level due to an OB level difference caused by an increase in dark current of the image sensor, such as during exposure, high temperature, and long exposure. This is an example of a configuration that is possible.

(Third embodiment)
FIG. 8 is a detailed flowchart for explaining a third embodiment of the pre-development calculation processing in step S128 of FIG.

The pre-development calculation process in step S128 is performed in the image processing circuit 20.
First, the image processing circuit 20 performs WB (white balance) calculation processing using captured image data (step S601).

  Next, the image processing circuit 20 detects a pixel having a minimum output value from pixels excluding defective pixels in the effective pixel range in the captured image data, and uses the output value of the pixel as the effective pixel portion minimum value. (Step S602).

Subsequently, in the image processing circuit 20, it is determined whether or not the effective pixel minimum value obtained in step S602 is smaller than a predetermined value (step S603). The captured image data is clamped with the value set to the dark level (step S606). The predetermined value used in the comparison in step S603 is a reference value for determining whether or not the effective pixel minimum value obtained in step S602 is appropriate as the dark level. For example, various settings in the manufacturing process of the imaging device of the present invention. It is calculated from a non-exposure image taken in advance in the value adjustment process, and stored in the nonvolatile memory 56 or the like.
If it is determined in step S603 that the minimum value within the effective pixel is equal to or greater than the predetermined value, the process proceeds to step S604, and an OB integration calculation process is performed to calculate an average of the output values of the OB portion in the captured image data. Get the value.

  Subsequently, the OB integral value obtained in step S602 and step S604 is compared with the value of the effective pixel minimum value (step S605). If the OB integration value is larger than the effective pixel minimum value, the effective pixel minimum value is determined. The captured image data is clamped with the value set to the dark level (step S606). If the minimum value in the effective pixel is larger than the OB integral value in step S605, the captured image data is clamped with the OB integral value as the dark level (step S607).

  When the series of processing is finished, the pre-development calculation processing routine S128 is finished.

  The embodiment of the present invention has been described above with reference to FIGS.

  In the description of the embodiment, it has been described that the single shooting / continuous shooting is switched using the single shooting / continuous shooting switch 68. However, the single shooting / continuous shooting is selected according to the operation mode selection in the mode dial 60. There is no problem even if it is configured to switch the copy.

  In the description of the embodiments, the dark level is determined by using the minimum value in the effective pixel as the dark level detection method in the effective pixel range. However, in order to remove the influence of the defective pixel or the like, several tens of pixels are counted from the minimum value. The signal output value of the predetermined pixel, such as a small value for the eye and several hundred pixels, may be used as the dark level. In addition, in order to remove the influence of variations in the output of each pixel due to random noise, two-dimensional fixed pattern noise, etc., the entire effective pixel range is divided into blocks formed of several pixels, and the average output value is minimized. It is good also as a dark level with the value of a block. In order to remove the influence of random noise or the like, the dark level may be a value obtained by adding a predetermined numerical value to the minimum value of the pixels in the entire range or a partial range in the effective pixel range.

In the description of the embodiment, the effective pixel range for detecting the dark level is set to the entire effective pixel range. However, the detection range is reduced due to shortening of the detection time or not being affected by shading in the screen. May be set as a part of the effective pixel range. For example, only a part of the effective pixel range close to the OB portion may be set as the detection range.
In the description of the embodiment described with reference to FIG. 7, the comparison between the OB integral value and the effective pixel minimum value is performed only when a specific mode called the night scene mode is selected, and the ISO sensitivity is 800. When it is larger, the sequence is performed when any one of the ambient temperature of 30 ° C. or more and the shutter speed of 1 second or more is satisfied, but the present invention is not limited to this, and for example, ISO sensitivity and temperature A sequence in which the selection mode and the shooting conditions are freely combined may be used, such as comparing only when both satisfy the conditions, or comparing the OB integral value and the minimum value in the effective pixel unconditionally in the night scene mode.

  In some cases, under certain shooting conditions in which the dark current of the image sensor increases, such as when the temperature is extremely high or when the shutter time is very long, a non-exposure image as in the conventional example is captured and the image is captured. Alternatively, a sequence incorporating a method for obtaining the OB level difference from the above may be adopted.

  In the description of the embodiment, it has been described that the mirror 130 is moved to the mirror-up position and the mirror-down position to perform the photographing operation. However, the mirror 130 is configured as a half mirror, and the photographing operation is performed without moving. There is no problem even if it is done.

  The recording media 200 and 210 are not only memory cards such as PCMCIA cards and compact flash (registered trademark), hard disks, but also micro DAT, magneto-optical disks, optical disks such as CD-R and CD-WR, DVDs, and the like. Of course, there is no problem even if it is composed of a phase change type optical disk or the like.

  Of course, there is no problem even if the recording media 200 and 210 are composite media in which a memory card and a hard disk are integrated. Further, there is no problem even if a part of the composite medium is detachable.

  In the description of the embodiments, it has been described that the recording media 200 and 210 are separated from the image processing apparatus 100 and can be arbitrarily connected. However, any or all of the recording media are connected to the image processing apparatus 100. Of course, there is no problem even if it remains fixed.

  Further, the recording medium 200 or 210 may be connected to the image processing apparatus 100 in any number of single or plural.

  In the above description, the recording media 200 and 210 are mounted on the image processing apparatus 100. However, the recording medium may have any combination of a single or a plurality of recording media.

  In the present embodiment, the image pickup apparatus that clamps using the signal from the OB section or the effective pixel section has been described. However, the image pickup apparatus is used only for long-second shooting or only when the ambient temperature is high. An imaging device that clamps using a signal from an effective pixel instead of the OB unit may be used.

  The present invention can be used in an imaging apparatus such as a digital camera or a video camera that captures, records, and reproduces still images and moving images.

It is a block diagram of a configuration of an embodiment of the present invention. It is a part of flowchart of the main routine of a present Example. It is a part of flowchart of the main routine of a present Example. 3 is a flowchart of a distance measurement / photometry processing routine of the present embodiment. It is a flowchart of the imaging | photography process routine of a present Example. It is a flowchart explaining the 1st Example of the pre-development arithmetic processing routine of a present Example. It is a flowchart explaining the 2nd Example of the pre-development arithmetic processing routine of a present Example. It is a flowchart explaining the 3rd Example of the pre-development arithmetic processing routine of a present Example. It is a part of explanatory drawing explaining the influence on the picked-up image image by OB level | step difference. It is a part of explanatory drawing explaining the influence on the picked-up image image by OB level | step difference.

Explanation of symbols

12 shutters, 14 image sensors, 16 A / D converters, 18 timing generators,
20 image processing circuit, 22 memory control circuit, 24 image display memory, 26 D / A converter, 28 image display unit,
30 memory, 32 image compression / decompression circuit,
40 shutter control means, 42 distance measuring means, 44 thermometer, 46 photometric 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, 69 ISO sensitivity switch,
70 operation unit, 72 power switch,
80 power control means, 82 connector, 84 connector, 86 power supply means,
90 interface, 92 connector, 94 interface, 96 connector, 98 recording medium attachment / detachment detecting means,
100 image processing apparatus, 104 optical viewfinder, 106 lens mount,
110 communication means, 112 connector (or antenna),
120 interface, 122 connector, 130 mirror, 132 mirror,
200 recording medium, 202 recording section, 204 interface, 206 connector,
210 recording medium, 212 recording unit, 214 interface, 216 connector,
300 lens unit, 306 lens mount, 310 photographing lens, 312 aperture, 320 interface, 322 connector,
340 Exposure control means, 342 Distance measurement control means, 344 Zoom control means, 350 Lens system control circuit

Claims (5)

Comprising a plurality of pixels for converting into an electrical signal an optical image exposure, an imaging element consisting of a number of effective picture portion and the optical black region unit,
Detecting means for detecting the minimum output value of the entire range or a partial range in the effective pixel portion of the image sensor as the effective pixel portion minimum value ;
An OB integration means for calculating an average value of output signals in the entire range or a partial range of the optical black area portion and obtaining an OB integral value ;
A black level selection means for comparing the effective pixel portion minimum value and the OB integral value, and selecting the smaller one of the effective pixel portion minimum value and the OB integral value as a black level;
Correction means for correcting the output signal of the image sensor at the black level selected by the black level selection means;
An imaging apparatus comprising: The detecting device, the imaging apparatus according to claim 1, wherein the detecting as the effective pixel section minimum value minimum output value of the part range adjacent to the OB portion in the effective pixel portion. It said detecting means, when the shutter speed set is less than the time predetermined seconds, the image pickup apparatus according to claim 1, wherein the detecting the effective pixel section minimum. It said detecting means, when the ambient temperature is a predetermined temperature or less, the imaging apparatus according to claim 1, wherein the detecting the effective pixel section minimum. It comprises a plurality of pixels, converts an optical image exposed by an image sensor consisting of an effective pixel portion and an optical black region portion into an electrical signal,
The minimum output value of the entire or partial range within the effective pixel portion of the image sensor is detected as the effective pixel minimum value, and the average value of the output signals of the entire or partial range of the optical black region portion is calculated. To obtain the OB integral value ,
The effective pixel portion minimum value is compared with the OB integral value, and the smaller one of the effective pixel portion minimum value and the OB integral value is selected as a black level,
An imaging method comprising correcting an output signal of the imaging element with the black level .