JP2006157677A - Imaging unit, image processing apparatus, and signal processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent color reproducibility from deteriorating due to incomplete transfer, in particular, to prevent color reproducibility from deteriorating at high sensitivity. <P>SOLUTION: There are provided an imaging element (14) which generates electric charge, corresponding to the quantity of incident light and converts out electric charge into an electrical signal; an ISO sensitivity switch (69) for setting the sensitivity; a nonvolatile memory (56) for storing a correction value corresponding to charge transfer efficiency inside the imaging element for each of different sensitivities; and an image processing unit (20) which acquires, from the memory, a correction value corresponding to the sensitivity set by the ISO sensitivity switch and uses the acquired correction value, to correct the electrical signal outputted from the imaging element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image pickup apparatus using an image pickup device such as a CCD or a CMOS image sensor, an image processing apparatus for processing an electric signal output from the image pickup apparatus, and a signal processing method.

  Currently, a memory card having a solid-state memory element is used as a recording medium, such as a digital camera that records and reproduces a still image or a moving image captured by a solid-state image sensor such as a CCD or CMOS (hereinafter referred to as “image sensor”). Imaging devices are already commercially available.

  An image pickup element used in such an image pickup apparatus basically has a configuration in which input light is converted into a signal charge, stored in a photoelectric conversion storage unit, and transferred by a subsequent circuit.

  FIG. 10 is a circuit diagram illustrating an example of a CMOS sensor pixel. 1001 is a unit pixel, 1002 is a photodiode (PD) for accumulating signal charges generated by incident light, 1003 is an amplifying MOS transistor as an amplifying means for outputting an amplified signal corresponding to the signal charge amount, and 1004 is a signal A floating diffusion (FD) portion 1005 that receives charges and connects to the gate electrode of the amplifying MOS transistor 1003, 1005 is a MOS transistor (Tx), 1006 as transfer means for transferring the signal charge accumulated in the PD 1002 to the FD portion 1004 A MOS transistor (Tres) for resetting the FD portion 1004, and a MOS transistor 1007 for selecting an output pixel.

  Reference numeral 1008 denotes a control line for applying a pulse to the gate of Tx1005 to control the charge transfer operation. Reference numeral 1009 denotes a control line for applying a pulse to the gate of Tres1006 to control the reset operation. Reference numeral 1010 denotes the MOS transistor 1007. A control line 1011 for applying a pulse to the gate to control the selection operation is a power supply line, which is connected to the drain of the amplification MOS transistor 1003 and the drain of the reset MOS transistor 1006 and supplies a power supply potential to them. ing. Reference numeral 1012 denotes an output line for outputting an amplification signal of the selected pixel, 1013 operates as a constant current source, MOS transistor forming an amplification MOS transistor 1003 and a source follower, and 1014 operates so that the MOS transistor 1013 operates at a constant current. This wiring supplies a high potential to the gate electrode of the MOS transistor 1013.

  The pixel 1001 arranged in a two-dimensional matrix forms the pixel region of the two-dimensional solid-state imaging device. In the matrix configuration, the output line 1012 is a common line common to the pixels in each column, and is controlled. The lines 1008, 1009, and 1010 are common lines common to the pixels in each row, and only the pixels in the row selected by the control line 1010 are output as signals to the output line 1012.

  Next, the operation of the pixel will be briefly described. First, a pulse is applied to the control line 1009 for the pixel in the row where the selection MOS transistor 1007 is turned on by the control line 1010. As a result, Tres 1006 is turned on, and the FD unit 1004 is reset. At this time, since the source follower is formed by the amplification MOS transistor 1003 and the constant current MOS transistor 1013, an output potential corresponding to the reset potential appears on the output line 1012. Next, by applying a pulse to the control line 1008, the Tx 1005 is turned on, and the signal charge accumulated in the PD 1002 is transferred to the FD unit 1004. As a result, the potential of the FD portion 1004 changes by a voltage corresponding to the signal charge amount, and the potential change appears on the output line 1012. Since the reset potential appearing on the output line 1012 is affected by variations in the threshold voltage value of the amplifying MOS transistor 1003 and noise such as reset noise when the FD portion 1004 is reset, the signal potential is theoretically increased. The corresponding potential change is a signal that does not contain noise.

  In the two-dimensional CMOS sensor, a readout circuit for removing this noise and taking out only a signal is connected to the output line 1012. There are several types of readout circuits, such as one that removes noise by a clamp circuit, and one that removes noise by holding noise and noise + pure signal separately and guiding them to the differential amplifier at the final stage during horizontal scanning readout. Such a configuration has been proposed, but since it is not directly related to the present invention, a detailed description thereof will be omitted.

  Next, FIG. 11 shows a cross-sectional structure of the PD 1002, Tx 1005, and FD portion 1004 of the pixel. In the figure, 2015 is an N-type semiconductor substrate, 2016 is a P-type well, 2017 is an N-type semiconductor region formed in the well 2016, and a photodiode PD1002 is formed by the well 2016 and the region 2017. A signal charge is accumulated in 2017. Reference numeral 2018 denotes an N-type semiconductor region formed in the well 2016 and serves as the FD portion 1004. Reference numeral 2019 denotes a gate electrode of Tx1005. Regions 2017 and 2018 are a source region and a drain region of Tx1005, respectively. A wiring 2020 is connected to the region 2018 and is connected to the gate of the amplification MOS transistor 1003. The signal charges accumulated in the region 2017 are all transferred to the N-type semiconductor region 2018 serving as the FD portion 1004 during the transfer operation, and immediately after the transfer, the N-type impurity concentration in the region 2017 is completely depleted. Is set. Therefore, the signal charge accumulation in the PD 1002 starts immediately after the signal charge transfer. When the signal charge accumulation ends, the row to which the pixel belongs is selected again, and the signal charge accumulated in the region 2017 of the PD 1002 enters the region 2018. It is time to be transferred.

  In practice, however, complete charge transfer is extremely difficult even when the formation conditions such as the concentration of the transfer path from the region 2017 of the PD 1002 to the N-type semiconductor region 2018 serving as the FD 1004 are set to theoretically optimum values. In other words, a slight error such as the size and concentration of each part that always occurs during manufacturing generates a potential pocket on the transfer path, so even if charge transfer is extremely close to ideal (close to perfect), The cause of incomplete transfer (charge loss) of several levels of charges cannot be completely eliminated.

  As a countermeasure for the incomplete charge transfer, the potential pocket or the like can be obtained by temporarily changing the power supply potential to the semiconductor region from the high level to the low level when the gate of the transfer MOS transistor and the reset MOS transistor are turned on immediately after the signal charge transfer. Has been proposed (see, for example, Patent Document 1).

  As for incomplete transfer, there is a similar problem in the CCD sensor, and as a countermeasure against this problem, there is also a proposal to make the transfer electrode gap of the vertical transfer CCD narrower than the transfer electrode gap of the horizontal transfer CCD. (For example, refer to Patent Document 2).

  Furthermore, as a part of noise countermeasures, a method is generally used to reduce the influence of noise by comparing the signal output and dark output to make light output, but in this method signal output and dark output are generally used. Concerned that a level difference occurs at the time of acquisition, it has also been proposed to reduce a level difference by adding a predetermined DC voltage to the amplified output (see, for example, Patent Document 3).

JP 2003-169256 A Japanese Patent Registration No. 03270254 JP 2002-135651 A

  By the way, in recent years, the number of pixels of an image sensor used in an image pickup apparatus such as a digital camera has been increased, and the area per pixel tends to increase while the area of the image pickup surface remains unchanged. is there. Therefore, the amount of charge that can be captured per pixel is inevitably reduced.

  In addition, an amplification unit is provided after the pixel unit so that images with appropriate exposure can be taken even when there are few light signals when shooting in a low-brightness environment. In the case of high-sensitivity shooting (for example, ISO 800), the amount of charge captured by the image sensor is reduced by the sensitivity ratio in the case of exposure shooting equivalent to normal sensitivity (for example, equivalent to ISO 100).

  When the charge amount is small as described above, the influence of incomplete transfer increases even if the amount of electrons remaining after transfer is the same as when the charge amount is large. In particular, the linearity tends to deteriorate under shooting conditions of high sensitivity and low luminance.

  Further, the image sensor is provided with a color filter for color separation, and even if the amount of light passing through the color filter and entering the pixel surface is the same, the subject light source color and the color filter Due to the difference in the photoelectric conversion rate of the light of the wavelength corresponding to each color (RGB, etc.), the difference in the amount of charge obtained is obtained. Color ratio is greatly different.

  An example of the above problem will be described with reference to FIGS. FIG. 12 is a graph showing the linearity characteristic of the exposure-charge amount in the image sensor, and it is ideal that the exposure-charge amount is γ = 1. However, as described above, in the portion with a small amount of charge, the influence of incomplete charge transfer is large, and linearity cannot be maintained. In addition, since the amount of charge of each color separated by the color filter varies depending on the wavelength of the light source, the linearity is greatly reduced for the pixel of the color with the least charge. In FIG. 12, the charge amount of the red (R) pixel is the smallest, and the decrease of the charge amount of the R pixel is the largest on the low luminance (low exposure) side.

  FIGS. 13A to 13C show how the reduction in linearity affects the amount of charge of each color when shooting a low-luminance subject as a color ratio, and green (appropriate exposure (X axis of graph: 0)) G) The ratio when the exposure changes when the ratio of the red (R) pixel and the blue (B) pixel with respect to the pixel is 1. 13A shows the case of ISO 100, FIG. 13B shows the case of ISO 800, and FIG. 13C shows the case of ISO 1600.

  Since the charge amount is relatively large at ISO 100, as shown in FIG. 13A, R / G and B / G are almost 1 on the proper exposure (= 0) and the low exposure side (−2 to −3). It can be seen that stable color reproduction is possible even with low exposure. On the other hand, in the ISO 800 of FIG. 13B, the influence of incomplete charge transfer appears on the R / G and B / G on the low exposure side (−2 to −3), and in the R / G, −4 to −8. %, And the ratio is further deteriorated in ISO 1600 of FIG. 13C, and it has come out to a portion exceeding -10%.

  Such deterioration of the color ratio is related to color reproduction of the image pickup apparatus and the like, and has a considerable influence on the deterioration of image quality.

  The present invention has been made in view of the above problems, and an object thereof is to prevent deterioration of color reproducibility due to incomplete transfer, particularly deterioration of color reproducibility with high sensitivity.

  In order to achieve the above object, the imaging device of the present invention generates an electric charge according to the amount of incident light, converts it into an electrical signal and outputs it, and according to the charge transfer efficiency in the imaging element, Correction means for correcting an electrical signal output from the image sensor.

  Further, the image processing apparatus of the present invention that processes an electrical signal output from an imaging device having an imaging device, according to an acquisition unit that acquires the electrical signal from the imaging device, and a charge transfer efficiency in the imaging device, Correction means for correcting the electrical signal acquired by the acquisition means.

  Further, the signal processing method of the present invention for processing an electrical signal output from an imaging device having an imaging element, according to the acquisition step of acquiring the electrical signal from the imaging device, and the charge transfer efficiency in the imaging element, A correction step of correcting the electrical signal acquired in the acquisition step.

  According to another configuration, the imaging apparatus of the present invention generates an electric charge according to the amount of incident light, converts it into an electrical signal and outputs it, sensitivity setting means for setting sensitivity, and the imaging A storage unit that stores a correction value corresponding to the charge transfer efficiency in the device for each different sensitivity, a correction value corresponding to the sensitivity set by the sensitivity setting unit is acquired from the storage unit, and the acquired correction value is obtained. And correcting means for correcting an electrical signal output from the image sensor.

  Furthermore, according to another configuration, the imaging apparatus of the present invention generates an electric charge according to the amount of incident light, converts it into an electrical signal and outputs it, a sensitivity setting means for setting sensitivity, and a predetermined setting. Based on the storage means for storing the reference correction value corresponding to the charge transfer efficiency in the image sensor at the reference sensitivity, the sensitivity set by the sensitivity setting means, and the reference correction value stored in the storage means And calculating means for calculating a correction value corresponding to the set sensitivity, and correcting means for correcting the electric signal output from the image sensor using the correction value calculated by the calculating means.

  Further, an image processing apparatus of the present invention that processes an electrical signal output from an imaging apparatus having imaging elements capable of imaging with different sensitivities includes sensitivity acquisition means for acquiring sensitivity at the time of imaging, and the imaging at the acquired sensitivity. Correction value acquisition means for acquiring a correction value corresponding to the charge transfer efficiency in the element, and correction means for correcting an electrical signal output from the imaging element using the correction value acquired by the correction value acquisition means. .

  Further, in the signal processing method of the present invention for processing an electrical signal output from an imaging device having an imaging device capable of imaging with different sensitivities, a sensitivity acquisition step of acquiring sensitivity at the time of imaging, and the imaging at the acquired sensitivity A correction value acquisition step of acquiring a correction value according to the charge transfer efficiency in the device, and a correction step of correcting the electric signal output from the imaging device using the correction value acquired in the correction value acquisition step. .

  According to the present invention, it is possible to prevent deterioration of color reproducibility due to incomplete transfer, particularly deterioration of color reproducibility with high sensitivity.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to an embodiment of the present invention. The image processing apparatus includes an image processing apparatus main body 100, recording media 200 and 210 that are detachably attached to the image processing apparatus main body 100, and a lens unit 300 that is detachably attached to the image processing apparatus main body 100. ing.

  The lens unit 300 is configured as an interchangeable lens type. In the lens unit, reference numeral 306 denotes a lens mount that mechanically couples the lens unit 300 to the image processing apparatus main body 100. The lens mount 306 includes various functions for electrically connecting the lens unit 300 to the image processing apparatus main body 100. Reference numeral 310 denotes a photographic lens group that captures a subject image, 312 denotes an aperture that adjusts the amount of light entering from the photographic lens 310, and 320 denotes an interface for connecting the lens unit 300 to the image processing apparatus main body 100 in the lens mount 306. Manage the interface. Reference numeral 322 denotes a connector that electrically connects the lens unit 300 to the image processing apparatus main body 100, and communicates control signals, status signals, data signals, and the like between the image processing apparatus main body 100 and the lens unit 300, and various voltages. A function of receiving or supplying a current is also provided. The connector 322 may be configured to transmit not only electrical communication but also optical communication, voice communication, and the like.

  The aperture control unit 340 controls the aperture 312 in cooperation with the shutter control unit 40 that controls the shutter 12 based on the photometric information from the photometric unit 46 of the image processing apparatus main body 100. The distance measurement control unit 342 controls focusing of the photographing lens group 310. The zoom control unit 344 controls zooming of the photographing lens group 310. The lens system control unit 350 controls the entire lens unit 300. The lens system control unit 350 includes a memory for storing operation constants, variables, programs, etc., identification information such as numbers unique to the lens unit 300, management information, function information such as an open aperture value, a minimum aperture value, and a focal length. Also, it has a function of a non-volatile memory that holds each setting value of the present and past.

  In the image processing apparatus main body 100, reference numeral 106 denotes a lens mount that mechanically couples the lens unit 300 to the image processing apparatus main body 100. The lens unit 300 is electrically connected to the image processing apparatus main body 100 in the lens mount 106. Various functions to connect to are included.

  14 is an image sensor that converts an optical image into an electrical signal, and transfers the electrical signal that has been subjected to desired amplification (amplification associated with a set ISO sensitivity, etc.) to an A / D converter 16 that will be described later. 14 is a shutter for controlling the exposure amount to 14. A light beam incident on the lens group 310 of the lens unit 300 is guided through the diaphragm 312, the lens mounts 306 and 106, 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. Reference numeral 18 denotes a timing at which a clock signal and a control signal are supplied to the image sensor 14, the A / D converter 16, and the D / A converter 26. A generation circuit, which is controlled by the memory control unit 22 and the system control unit 50.

  An image processing unit 20 performs predetermined pixel interpolation processing, color conversion processing, offset processing, and the like on the data from the A / D converter 16 or the data from the memory control unit 22. In addition, the image processing unit 20 performs predetermined calculation processing using the captured image data as necessary, and the system control unit 50 performs the shutter control unit 40 and the distance measurement based on the obtained calculation result. The unit 42 is subjected to TTL (through the lens) AF (autofocus) processing, AE (automatic exposure) processing, and EF (flash pre-flash) processing. Further, the image processing unit 20 performs predetermined calculation processing using the captured image data, and also performs TTL AWB (auto white balance) processing based on the obtained calculation result.

  In the present embodiment, since the image processing apparatus is configured to include the distance measurement unit 42 and the photometry unit 46, the AF process, the AE process, and the EF process are performed using the distance measurement unit 42 and the photometry unit 46. A configuration may be adopted in which each processing is performed and each of the AF processing, AE processing, and EF processing using the image processing unit 20 is not performed. Alternatively, AF processing, AE processing, and EF processing are performed using the distance measuring unit 42 and the photometry unit 46, and further, AF processing, AE processing, and EF processing using the image processing unit 20 are performed. It is good also as a structure.

  A memory control unit 22 controls the A / D converter 16, the timing generation circuit 18, the image processing unit 20, the image display memory 24, the D / A converter 26, the memory 30, and the compression / decompression circuit 32. Data of the A / D converter 16 is written into the image display memory 24 or the memory 30 through the image processing unit 20 and the memory control unit 22 or directly through the memory control unit 22.

  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 is converted into analog signals by the D / A converter 26. And is displayed by the image display unit 28. An electronic viewfinder function can be realized by sequentially displaying image data captured using the image display unit 28. The image display unit 28 can arbitrarily turn on / off the display according to an instruction from the system control unit 50. When the display is turned off, the power consumption of the image processing apparatus main body 100 is greatly reduced. be able to.

  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 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 unit 50.

  A compression / decompression circuit 32 compresses / 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 again in the memory. Write to 30.

  The shutter control unit 40 controls the shutter 12 in cooperation with the aperture control unit 340 that controls the aperture 312 based on the photometry information from the photometry unit 46.

  The distance measuring unit 42 is for performing AF (autofocus) processing, and a light beam incident on the lens 310 of the lens unit 300 is converted into an aperture 312, lens mounts 306 and 106, a mirror 130 and a mirror 130 by a single lens reflex method. The in-focus state of the image formed as an optical image can be measured by making the light incident on the distance measuring unit 42 through the distance measuring sub-mirror. The thermometer 44 can detect the temperature of the shooting environment. When the thermometer 44 is in the image sensor 14, the dark current of the image sensor 14 can be predicted more accurately.

  The photometry unit 46 is for performing an AE (automatic exposure) process. A light beam incident on the lens 310 of the lens unit 300 is converted into a diaphragm 312, lens mounts 306 and 106, mirrors 130 and 132, and a single lens reflex system. By making it enter the photometric unit 46 through a photometric lens (not shown), the exposure state of the image formed as an optical image can be measured. The photometry unit 46 also has an EF (flash dimming) processing function in cooperation with the flash 48. The flash 48 also has an AF auxiliary light projecting function and a flash light control function.

  The system control unit 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 unit 20. It is also possible to perform exposure control and AF (autofocus) control using the video TTL method. Furthermore, AF (autofocus) control may be performed using both the measurement result by the distance measuring unit 42 and the calculation result obtained by calculating the image data captured by the image sensor 14 by the image processing unit 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 image sensor 14 by the image processing unit 20.

  A system control unit 50 controls the entire image processing apparatus main body 100, and a memory 52 stores constants, variables, programs, and the like for operation of the system control unit 50. Reference numeral 54 denotes a notification unit such as a display device or a speaker that notifies a user of an operation state or a message using characters, images, sounds, and the like in accordance with execution of a program in the system control unit 50. One or a plurality of positions are provided near the 100 operation units in an easily visible position. For example, it is composed of a combination of LCD, LED, sound generation element, and the like. In addition, the notification unit 54 has a part of its function installed in the optical viewfinder 104.

  Among the display contents of the notification unit 54, what is displayed on the LCD or the like includes single shot / continuous shooting display, self-timer display, compression rate display, ISO (International Organization for Standardization) sensitivity display, recording pixel number display, recording Number of shots display, number of remaining shots display, shutter speed display, aperture value display, exposure compensation display, flash display, red-eye reduction display, macro shooting display, buzzer setting display, battery level display for clock, battery level display, error display , Information display with a plurality of digits, 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, etc. There is.

  Among the display contents of the notification unit 54, what is displayed in the optical viewfinder 104 includes in-focus display, shooting preparation completion display, camera shake warning display, flash charge display, flash charge completion display, shutter speed display, aperture value. Display, exposure correction display, recording medium writing operation display, and the like.

  Further, among the display contents of the notification unit 54, what is displayed by an LED or the like includes, for example, in-focus display, shooting preparation completion display, camera shake warning display, flash charge display, flash charge completion display, recording medium writing operation display, Macro shooting setting notification display, secondary battery charge status display, and the like. Furthermore, among the display contents of the notification unit 54, what is displayed on a lamp or the like includes, for example, a self-timer notification lamp. 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, ISO sensitivity, setting values such as an offset correction amount (or offset correction value) described later according to the ISO sensitivity, and data such as a setting mode. Reference numerals 60, 62, 64, 66, 68, 69, and 70 are operation means for inputting various operation instructions of the system control unit 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.

  Hereinafter, the operation means will be described. 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 mode such as a mode, a sports shooting mode, a night view shooting mode, a panoramic shooting mode, and the like 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 (auto focus) processing, AE (auto exposure) processing, AWB (auto white balance) processing, EF (flash pre-flash) processing, and the like. Instruct to start operation.

  Reference numeral 64 denotes a shutter switch SW2, which is turned on upon completion of an operation of a shutter button (not shown), and an exposure process for writing a signal read from the image sensor 14 to the memory 30 via the A / D converter 16 and the memory control unit 22. Development processing using calculation in the image processing unit 20 or the memory control unit 22, recording processing for reading out image data from the memory 30, compression in the compression / decompression circuit 32, and writing the image data in 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 on the image display unit 28 in the shooting mode state.

  68 is a single-shot / continuous-shot switch. When the shutter switch SW2 (64) is pressed, the single-shot mode in which one frame is shot and put into a standby state, and while the shutter switch SW2 (64) is pressed, continues. You can set the continuous shooting mode to continue shooting.

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

  Reference numeral 70 denotes an operation unit composed of various buttons, a touch panel, etc., a menu button, a set button, a macro / non-macro switching button, a multi-screen playback page break button, a flash setting button, a single shooting / continuous shooting / self-timer switching button, and menu movement. + (Plus) button, menu movement-(minus) button, playback image movement + (plus) button, playback image-(minus) button, shooting image quality selection button, exposure compensation button, date / time setting button, panorama mode, etc. Selection / switch button for selecting and switching various functions when executing shooting and playback, Decision / execution button for determining and executing various functions when performing shooting and playback in panorama mode, etc., image display Image display ON / OFF switch for setting ON / OFF of the unit 28, shooting immediately after shooting There is a quick review ON / OFF switch for setting a quick review function of automatically playing back image data. The functions of the plus button and the minus button can be selected more easily with numerical values and functions by providing a rotary dial switch.

  Further, the operation unit 70 is a switch for selecting a compression rate for JPEG (Joint Photographic Expert Group) compression or for selecting a CCD RAW mode in which the signal of the image sensor 4 is digitized and recorded on a recording medium. Auto focus operation is started in response to pressing of the switch, playback switch for setting each function mode such as mode switch, playback mode / multi-screen playback / erase mode, PC (personal computer) connection mode, etc. There is an AF mode setting switch for setting a one-shot AF mode that keeps the in-focus state once in focus, and a servo AF mode that keeps autofocusing continuously while the shutter switch SW1 is pressed. .

  Reference numeral 72 denotes a power switch, which can switch and set the power-on and power-off modes of the image processing apparatus main body 100. In addition, the power switch 72 can also switch and set 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 main body 100. .

  A power control unit 80 includes a battery detection circuit, a DC-CD converter, a switch circuit that switches a block to be energized, and the like, and detects the presence / absence of a battery, the type of battery, and the remaining battery level. In addition, the DC-DC converter is controlled based on an instruction from the system control unit 50, and a necessary voltage is supplied to each unit including the recording medium for a necessary period.

  Reference numerals 82 and 84 denote connectors, 86 denotes a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a NiCd battery, NiMH battery, or 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. It is a recording medium attachment / detachment detection circuit that detects whether or not the recording medium is present.

  In the present embodiment, it is assumed that there are two interfaces and connectors for attaching a recording medium. Of course, the interface and the connector for attaching the recording medium may have a single or a plurality of systems, 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 the connector can be configured using a PCMCIA (Personal Computer Memory Card International Association) card, a CF (Compact Flash (registered trademark)) card, or the like. When the interfaces 90 and 94 and the connectors 92 and 96 are configured using a PCMCIA card, a CF (registered trademark) card, or the like, a LAN card, modem card, USB (Universal Serial Bus) card, IEEE ( By connecting various communication cards such as 1394 cards, P1284 cards, SCSIS small computer system interface) cards, PHS communication cards, and other peripheral devices such as computers and printers It is possible to transfer image data and management information attached to the image data.

  Reference numeral 104 denotes an optical viewfinder, which guides light incident on the lens 310 of the lens unit 300 through the aperture 312, the lens mounts 306 and 106, and the mirrors 130 and 132 by the single-lens reflex method, and forms an image as an optical image. Can do. Thereby, it is possible to perform photographing using only the optical viewfinder without using the electronic viewfinder function of the image display unit 28. In the optical viewfinder 104, some functions of the notification 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 circuit 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 main body 100 to another device by the communication circuit 110 or an antenna in the case of wireless communication.

  The interface 120 is an interface for connecting the image processing apparatus main body 100 to the lens unit 300 in the lens mount 106.

  The connector 122 electrically connects the image processing apparatus main body 100 to the lens unit 300. The lens attachment / detachment detection unit 124 detects whether or not the lens unit 300 is attached to the lens mount 106 and / or the connector 122. The connector 122 transmits a control signal, a status signal, a data signal, and the like between the image processing apparatus main body 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. The mirrors 130 and 132 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 numerals 200 and 210 denote recording media such as a memory card and a hard disk. The recording media 200 and 210 include recording units 202 and 212 each composed of a semiconductor memory, a magnetic disk, and the like, interfaces 204 and 214 with the image processing apparatus main body 100, connectors 206 for connecting with the image processing apparatus main body 100, and 216.

  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, and phase changes such as DVDs. Of course, it may be constituted by a type optical disk or the like.

  The recording media 200 and 210 may be a composite medium in which a memory card and a hard disk are integrated. Further, a part of the composite medium may be detachable.

(First embodiment)
Next, the operation of the image processing apparatus according to the first embodiment having the above configuration will be described in detail with reference to FIGS.

<Main Routine of Image Processing Apparatus Main Body 100>
2 and 3 are flowcharts of a main routine of the image processing apparatus main body 100 according to the first embodiment.

  When power is supplied to the image processing apparatus main body 100 such as battery replacement, the system control unit 50 initializes flags such as a flash flag (to be described later), control variables, and the like, and performs predetermined initial settings necessary for each unit of the image processing apparatus main body 100. This is performed (step S101). Next, the system control unit 50 determines the set position of the power switch 72 (step S102).

  If the power switch 72 has been set to power OFF ("Power OFF" in step S102), the display on each display unit is changed to the end state, and necessary parameters, setting values, and settings including flags and control variables are set. The mode is recorded in the non-volatile memory 56, and a predetermined termination process such as shutting off unnecessary power sources of the respective parts of the image processing apparatus main body 100 including the image display unit 28 is performed by the power control unit 80 (step S103). Return to S102. If the power switch 72 has been set to power ON (“power ON” in step S102), the system control unit 50 uses the power control unit 80 to determine the remaining capacity and operating status of the power source 86 configured by a battery or the like. It is determined whether there is a problem in the operation of the image processing apparatus main body 100 (step S104).

  If there is a problem with the power supply 86 (NO in step S104), a predetermined warning display output or warning sound output is performed using an image or sound using the notification unit 54 (step S105), and then the process returns to step S102. If there is no problem with power supply 86 (YES in step S104), system control unit 50 determines the set position of mode dial switch 60 (step S106). If the mode dial switch 60 is set to the shooting mode (“shooting mode” in step S106), the process proceeds to step S108. If the mode dial switch 60 is set to another mode (“other mode” in step S106), the system control unit 50 executes a process corresponding to the selected mode (step S107), and performs the process. If completed, the process returns to step S102.

  When the mode dial switch 60 is set to the shooting mode, the system control unit 50 reads information such as various parameters and ISO sensitivity stored in the nonvolatile memory 56 (step S108) and records the information in the image processing apparatus main body 100. Determination of whether or not the 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 main body 100, particularly It is determined whether there is a problem in the recording / reproducing operation of the image data with respect to the recording medium (step S109). If there is a problem as a result of the determination (NO in step S109), a predetermined warning display output or warning audio output is performed using an image or sound using the notification unit 54 (step S105), and then the process returns to step S102. . If there is no problem as a result of the determination (YES in step S109), the process proceeds to step S110. In step S <b> 110, the system control unit 50 performs display output and sound output of various setting states of the image processing apparatus main body 100 using images and sound using the notification unit 54. If the image display of the image display unit 28 is ON, the image display unit 28 is also used to perform display output and audio output of various setting states of the image processing apparatus main body 100 using images and sounds, and the steps of FIG. The process proceeds to S121.

  In step S121, the system control unit 50 checks the state of the shutter switch SW1 (62). If the shutter switch SW1 (62) has not been pressed (“OFF” in step S121), the process returns to step S102. If the shutter switch SW1 (62) is pressed (“ON” in step S121), the system control unit 50 performs a distance measurement process to focus the photographing lens 10 on the subject, performs a photometry process, and performs an aperture value. Then, distance measurement / photometry processing for determining the shutter time 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 will be described later with reference to FIG.

  Next, the system control unit 50 checks the state of the shutter switch SW2 (64) (step S132). If the shutter switch SW2 (64) is not pressed (“OFF” in step S132), the system control unit 50 checks the state of the shutter switch SW1 (62) (step S133), and the shutter switch SW1 (62). If is ON, the process returns to step S132. On the other hand, if the shutter switch SW1 (62) is off, the process returns to step S102. If the shutter switch SW2 (64) is pressed (“ON” in step S132), the system control unit 50 determines whether or not the memory 30 has an image storage buffer area capable of storing captured image data ( Step S134).

  If there is no area where new image data can be stored in the image storage buffer area of the memory 30 (NO in step S134), the system control unit 50 uses the notification unit 54 to output a predetermined warning display by image or sound. After the warning voice is output (step S135), 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 in which one empty area cannot be secured on 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 S134, 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 that can store image data captured in the memory 30 (YES in step S134), the system control unit 50 captures an imaging signal obtained by imaging and accumulating charges for a predetermined time. Read out from the A / D converter 16, the image processing unit 20, the memory control unit 22, or directly from the A / D converter 16 through the memory control unit 22, an image captured in a predetermined area of the memory 30. A photographing process for writing data is executed (step S136). Details of this photographing process will be described later with reference to FIGS. When the photographing process step S136 is completed, the process proceeds to a defective pixel correction process (scratch correction process) step S139. The defective pixel correction is not related to the gist of the present invention, and the detailed description is omitted.

  Next, the system control unit 50 reads a part of the image data after the scratch correction process written in a predetermined area of the memory 30 through the memory control unit 22 and performs WB (white) necessary for performing the development process. Balance) integration calculation processing and OB (optical black) integration calculation processing are performed, and the calculation result is stored in the internal memory or the memory 52 of the system control unit 50. Next, the system control unit 50 uses the memory control unit 22 and, if necessary, the image processing unit 20 to read the captured image data after flaw correction written in a predetermined area of the memory 30, and the system control unit 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 results stored in the internal memory or the memory 52 (step S140).

  Then, the system control unit 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 S141), 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 unit 50 reads out the image data stored in the image storage buffer area of the memory 30 and uses a memory card or a 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 S142).

  The recording start processing for the recording medium 200 or 210 is performed every time image data that has been shot and finished a series of processing is newly written in the empty image portion of the image storage buffer area of the memory 30. It is executed against. Note that while writing image data to the recording medium 200 or 210, in order to clearly indicate that the writing operation is in progress, the notification unit 54 displays a recording medium writing operation display such as blinking an LED.

  Next, the system control unit 50 checks the state of the shutter switch SW1 (62) (step S143), and releases the shutter switch SW1 (62) while the shutter switch SW1 (62) is being pressed. If the shutter switch SW1 (62) has not been pressed, the process returns to step S102.

<Distance / photometry processing>
FIG. 4 is a flowchart showing a detailed operation of the distance measurement / photometry process in step S122 of FIG. In the distance measurement / photometry processing, communication of various signals between the system control unit 50 of the image processing apparatus main body 100 and the aperture control unit 340 or the distance measurement control unit 342 of the lens unit 300 is performed by the interface 120 and the connector 122. , The connector 322, the interface 320, and the lens control unit 350. The system control unit 50 starts an AF (autofocus) process using the imaging device 14, the distance measurement unit 42, and the distance measurement control unit 342 (step S201).

  Next, the system control unit 50 converts the light incident on the photographing lens group 310 of the lens unit 300 into a diaphragm 312, a lens mount 306, a lens mount 106 of the image processing apparatus main body 100, a mirror 130, and a distance measurement (not shown). By making the light incident on the distance measuring unit 42 through the sub mirror, the in-focus state of the image formed as an optical image is determined, and until it is determined to be in focus (until “YES” in step S203), While driving the lens 310 using the distance measurement control unit 342 of the lens unit 300, AF control is performed to detect the in-focus state using the distance measurement unit 42 of the image processing apparatus main body 100 (step S202). If it is determined that focus is achieved (YES in step S203), the system control unit 50 determines a focused distance point from the plurality of measured distance points on the shooting screen in step S204, and determines the determined distance point. The distance measurement data and / or setting parameters are stored in the internal memory of the system control unit 50 or the memory 52 together with the data, and the process proceeds to step S205.

  Subsequently, the system control unit 50 uses the photometry unit 46 to start an AE (automatic exposure) process (step S205). The system control unit 50 transmits the light beam incident on the lens 310 of the lens unit 300 through the aperture 312, the lens mount 306, the lens mount 106, the mirrors 130 and 132 of the image processing apparatus main body 100, and a photometric lens (not shown). The exposure state of the image formed as an optical image is measured by being incident on the photometry unit 46, and the exposure (AE) is set at the ISO sensitivity set in advance by the ISO sensitivity switch 69 and read in step S108. Is determined to be appropriate (until “YES” in step S207), using the photometry unit 46 of the image processing apparatus main body 100 while adjusting the aperture 312 using the aperture control unit 340 of the lens unit 300. Photometric processing is performed (step S206). If it is determined that the exposure (AE) is appropriate (YES in step S207), the system control unit 50 stores the photometric data and / or the setting parameter in the internal memory or the memory 52 of the system control unit 50, and proceeds to step S208. .

  Depending on the exposure (AE) result detected by the photometric processing in step S206, the shooting mode set by the mode dial switch 60, and the ISO sensitivity set by the ISO sensitivity switch 69, the system control unit 50 An aperture value (Av value) and a shutter speed (Tv value) are determined. Then, according to the shutter speed (Tv value) determined here, the system control unit 50 determines the charge accumulation time of the image sensor 14 and performs the photographing process with the same charge accumulation time.

  In step S208, the system control unit 50 determines whether or not a flash is necessary based on the measurement data obtained by the photometric process in step S206. If the flash is necessary, the flash flag is set and the flash 48 is charged (step S209) until the flash 48 is completely charged (step S210). If charging of flash 48 is completed (YES in step S210), the distance measurement / photometry processing routine is terminated.

<Shooting process>
5 and 6 are flowcharts showing the detailed operation of the photographing process in step S136 of FIG. In the photographing process, as in the distance measurement / photometry process, communication of various signals between the system control unit 50 of the image processing apparatus main body 100 and the aperture control unit 340 or the distance measurement control unit 342 of the lens unit 300 is performed. Is performed via the interface 120, the connector 122, the connector 322, the interface 320, and the lens control unit 350. The system control unit 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 of the system control unit 50 or the memory 52. As a result, the aperture 312 is driven to a predetermined aperture value (step S302).

  Next, the system control unit 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 unit 40 ( In step S305, exposure of the image sensor 14 is started (step S306). Here, the system control unit 50 determines whether or not the flash 48 is necessary based on the flash flag (step S307). When the flash 48 is necessary, the flash 48 is caused to emit light (step S308) and is not necessary. In step S309 of FIG. 6, the flash 48 is not emitted.

  Next, the system control unit 50 waits for the exposure of the image sensor 14 to end according to the photometric data (step S309), closes the shutter 12 by the shutter control unit 40 (step S310), and ends the exposure of the image sensor 14.

  Next, the system control unit 50 drives the aperture 312 to the open aperture value by the aperture control unit 340 of the lens unit 300 (step S311), and moves the mirror 130 to the mirror down position by a mirror driving unit (not shown). (Step S312). If the set charge accumulation time has elapsed (YES in step S313), the system control unit 50 ends the charge accumulation of the image sensor 14 (step S314), and then proceeds to the image signal read process (step S315). Details of the imaging signal readout processing performed in step S315 will be described later with reference to FIG.

  When the series of processing is finished, the photographing processing routine is finished.

<Imaging signal readout processing>
FIG. 7 is a flowchart showing a detailed operation of the imaging signal reading process in step S315 of FIG.

  The system control unit 50 confirms the ISO sensitivity set at the time of shooting processing (step S501), and among the offset correction amounts corresponding to the ISO sensitivity stored in advance in the memory 56, the offset corresponding to the confirmed ISO sensitivity. A correction amount is set in the image processing unit 20 (step S502). The offset correction amount corresponding to the incomplete charge transfer is set for each ISO sensitivity as the offset correction amount corresponding to the ISO sensitivity stored in advance. Subsequently, in step S503, the electric charge accumulated in the image sensor 14 in step S314 of FIG. 6 is read out and converted into digital data via the A / D converter 16 (step S504), and the offset set in step S502 by the image processing unit 20 is set. The correction amount is added (step S505), the captured image data is written to a predetermined area of the memory 30 via the memory control unit 22 (step S506), and the imaging signal readout processing routine is terminated.

  8A to 8C are examples showing the color ratio of low luminance linearity when the offset correction according to the first embodiment of the present invention is added to the imaging apparatus having the color ratio of FIGS. 13A to 13C described above. It is. 8A to 8C, as in FIGS. 13A to 13C, the ratio of red (R) pixels and blue (B) pixels based on green (G) pixels with appropriate exposure (X axis of graph: 0) is 1. In this case, the ratio when the exposure changes is shown.

  FIG. 8A shows the time of ISO 100, and accompanying the incomplete transfer of charge at ISO 100 (1 time) (for example, the charge for the incomplete transfer is A / D converted via the amplification unit at the subsequent stage in the image sensor 14. This is a value obtained by adding an offset correction amount α1 (corresponding to a value in the case of being performed). R / G and B / G change slightly in the positive direction on the low-exposure side (-2 steps to -3 steps) compared with the uncorrected case (FIG. 13A). There is no.

  FIG. 8B shows the time of ISO 800, and is obtained by adding an offset correction amount α8 associated with the incomplete transfer of charge at ISO 800 (8 times). The R / G value on the low exposure side (-3rd stage), which was -8% when uncorrected (FIG. 13B), has settled down to a difference of about -2%.

  FIG. 8C shows the time of ISO 1600, and is obtained by adding an offset correction amount α16 accompanying the incomplete transfer of charge at ISO 1600 (16 times). The value of R / G on the low exposure side (−3 steps) that exceeded −10% when uncorrected (FIG. 13C) is settled at a difference of about −2%.

  In the first embodiment of the present invention, the offset correction amount is α1 <α8 <α16. Further, the setting of the offset correction amount at the intermediate ISO sensitivity not described here is a value associated with each sensitivity (amplification degree of incomplete transfer charge).

  As described above, according to the first embodiment of the present invention, it is possible to prevent deterioration of color reproducibility due to incomplete transfer, particularly deterioration of color reproducibility with high sensitivity.

(Second Embodiment)
In the first embodiment, since the offset correction amount data is stored in the nonvolatile memory 56 for each ISO sensitivity, a considerable memory capacity is required.

  In addition, since the first embodiment is a sequence for performing offset correction for all ISOs, an actual acquired image (measured charge) can be obtained even at low sensitivity (for example, ISO 100) with little change in color ratio. There is a problem that correction is added.

  In the second embodiment of the present invention, in view of the above problems, no correction is performed when the photographing sensitivity is lower than a predetermined value, and even when offset correction is performed, an offset with respect to a predetermined reference photographing sensitivity (for example, ISO 1600) is set. When the amount is set and another shooting sensitivity is set, the offset amount is changed according to the ratio of the sensitivity difference from the reference shooting sensitivity.

  The configuration and operation sequence of the present embodiment are the same as those in the first embodiment of the present invention that has already been described, and will not be described.

<Imaging signal readout processing>
FIG. 9 is a flowchart showing the detailed operation of the imaging process performed in the second embodiment, which is performed in step S315 of FIG. 6 described in the first embodiment, and is executed instead of FIG. .

  The system control unit 50 checks the ISO sensitivity (hereinafter referred to as “set sensitivity”) X set during the photographing process (step S601), and stores a predetermined ISO sensitivity (hereinafter referred to as “predetermined sensitivity”). It is determined whether the sensitivity is higher or lower than Y (for example, ISO 800) (step S602). If the sensitivity is lower than the predetermined sensitivity Y, the offset correction amount is set to “0” (step S603). If the set sensitivity X is higher than the predetermined sensitivity Y, it is determined whether or not it is a reference photographing sensitivity β (for example, ISO 1600) (step S604). If the reference sensitivity β is set, an offset correction amount α is set (step S604). S605). If the reference sensitivity β is not set, X ÷ β × α is set as an offset correction amount (step S606). That is, if the sensitivity is lower than the predetermined sensitivity Y, the correction value is “0”. If the sensitivity is the reference sensitivity β, the preset offset amount α is the correction value. If the sensitivity is not the reference sensitivity β, the ratio of the set sensitivity X and the reference sensitivity β is used as a reference. A value multiplied by the offset correction amount α is set as a correction value.

  For example, if the set sensitivity X is ISO800, the reference sensitivity β is ISO1600, and the offset amount α when the reference sensitivity is set is 2LSB, ISO800 ÷ ISO1600 × 2LSB = 1LSB is the correction amount. If the predetermined sensitivity Y is ISO800 and the set sensitivity X is ISO400, the offset correction amount is 0 (= no correction).

  Subsequently, in step S607, the electric charge accumulated in the image sensor 14 in step S314 of FIG. 6 is read and converted into digital data via the A / D converter 16 (step S608), and the image processing unit 20 performs steps S603, S605, or S606. Is added (step S609), and the captured image data is written to a predetermined area of the memory 30 via the memory control unit 22 (step S610), and the imaging signal readout processing routine is terminated.

  In the second embodiment of the present invention, even if offset correction is not performed, offset processing is not performed at low sensitivity (for example, ISO 100) that does not cause a problem as a color ratio. Therefore, the color ratio result shown in FIG. 13A is obtained. Thus, with high sensitivity (for example, ISO 800, ISO 1600) in which a difference appears as the color ratio, the offset ratio is used to improve the color ratio as shown in FIG. 8B or 8C, leading to an improvement in image quality.

  As described above, according to the second embodiment of the present invention, it is possible to prevent deterioration of color reproducibility due to incomplete transfer, in particular, deterioration of color reproducibility with high sensitivity, as in the first embodiment. The memory for holding the offset correction amount can be saved.

  In the second embodiment, when a predetermined sensitivity or higher is set, the offset correction amount is always determined by the ratio between the set sensitivity and the reference sensitivity. However, the present invention is not limited to this, for example, In order to amplify the sensitivity, a ratio of only a change in sensitivity amplification in the first amplifying unit (for example, the amplifying unit in the image sensor) is provided in the case where amplifying units are provided in a plurality of locations. It is not deviated from the gist of the present invention to perform partial application such as changing the ratio and not changing the ratio to the sensitivity amplification in the second amplification unit (for example, the subsequent amplification unit outside the imaging device).

<Other embodiments>
Note that the present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a camera head, etc.), or a device (for example, a digital still camera, a digital video camera device, etc.) including a single device ).

  In the case of being configured from a plurality of devices, even if the offset correction amount data is held on the camera head side including the image sensor and the data is passed to the host computer when connected to the host computer, the host computer side The offset correction amount data may be held and data corresponding to the connected image sensor may be used.

  Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus, and the computer (or CPU or Needless to say, this can also be achieved by the MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included. Examples of the storage medium for storing the program code include a flexible disk, hard disk, ROM, RAM, magnetic tape, nonvolatile memory card, CD-ROM, CD-R, DVD, optical disk, magneto-optical disk, MO, and the like. Can be considered. Also, a computer network such as a LAN (Local Area Network) or a WAN (Wide Area Network) can be used to supply the program code.

  Furthermore, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

  When the present invention is applied to the above-described storage medium, the program code corresponding to the flowchart shown in FIG. 7 or FIG. 9 described above is stored in the storage medium.

It is a block diagram which shows the structure of the image processing apparatus in embodiment of this invention. It is a flowchart of the main routine of the image processing apparatus main body in the 1st Embodiment of this invention. It is a flowchart of the main routine of the image processing apparatus main body in the 1st Embodiment of this invention. It is a flowchart which shows the detailed operation | movement of the ranging / photometry process in the 1st Embodiment of this invention. It is a flowchart which shows the detailed operation | movement of the imaging | photography process in the 1st Embodiment of this invention. It is a flowchart which shows the detailed operation | movement of the imaging | photography process in the 1st Embodiment of this invention. It is a flowchart which shows the detailed operation | movement of the imaging signal read-out process in the 1st Embodiment of this invention. It is a figure which shows the color ratio of the low-intensity linearity after offset correction | amendment at the time of the imaging sensitivity ISO100 in the 1st Embodiment of this invention. It is a figure which shows the color ratio of the low-intensity linearity after offset correction | amendment at the time of the imaging sensitivity ISO800 in the 1st Embodiment of this invention. It is a figure which shows the color ratio of the low-intensity linearity after offset correction | amendment in the case of the imaging sensitivity ISO1600 in the 1st Embodiment of this invention. It is a flowchart which shows the detailed operation | movement of the imaging signal read-out process in the 2nd Embodiment of this invention. It is a circuit diagram of a conventional CMOS sensor pixel. It is sectional drawing of the conventional CMOS sensor pixel. It is a figure which shows the output (exposure-charge amount) linearity data of the conventional image pick-up element. It is a figure which shows the color ratio of the conventional low-intensity linearity in the case of imaging | photography sensitivity ISO100. It is a figure which shows the color ratio of the conventional low-intensity linearity in the case of imaging | photography sensitivity ISO800. It is a figure which shows the color ratio of the conventional low-intensity linearity in the case of imaging | photography sensitivity ISO1600.

Explanation of symbols

1001: Unit pixel 1002: Photodiode (PD)
1003: MOS transistor for amplification 1004: Floating diffusion part (FD)
1005: Transfer MOS transistor (Tx)
1006: Reset MOS transistor (Tres)
1007: MOS transistor for output pixel selection 14: Image sensor 15: A / D converter 20: Image processing circuit 50: System control circuit 52: Memory 56: Non-volatile memory

Claims (21)

An image sensor that generates electric charge according to the amount of incident light, converts it into an electrical signal, and outputs it,
An image pickup apparatus comprising: correction means for correcting an electric signal output from the image pickup element in accordance with charge transfer efficiency in the image pickup element. An image sensor that generates electric charge according to the amount of incident light, converts it into an electrical signal, and outputs it,
Sensitivity setting means for setting the sensitivity;
Storage means for storing a correction value according to the charge transfer efficiency in the image sensor for each different sensitivity;
A correction unit that acquires a correction value corresponding to the sensitivity set by the sensitivity setting unit from the storage unit, and corrects an electrical signal output from the image sensor using the acquired correction value. An imaging device. An image sensor that generates electric charge according to the amount of incident light, converts it into an electrical signal, and outputs it,
Sensitivity setting means for setting the sensitivity;
Storage means for storing a reference correction value according to the charge transfer efficiency in the image sensor at a predetermined reference sensitivity;
An arithmetic means for calculating a correction value corresponding to the set sensitivity based on the sensitivity set by the sensitivity setting means and the reference correction value stored in the storage means;
An image pickup apparatus comprising: correction means for correcting an electric signal output from the image pickup device using the correction value calculated by the calculation means.   The image pickup apparatus according to claim 1, wherein the charge transfer efficiency in the image pickup device is a charge amount lost during charge transfer in the charge image pickup device.   The imaging unit according to claim 3, wherein the calculation unit calculates a correction value based on the reference correction value according to a ratio between the reference sensitivity and the sensitivity set by the sensitivity setting unit. apparatus.   4. The apparatus according to claim 3, further comprising a control unit that performs control so that the correction by the correction unit is not performed when the sensitivity set by the sensitivity setting unit is lower than a predetermined sensitivity lower than the reference sensitivity. Or the imaging device of 5.   The imaging apparatus according to claim 1, wherein the correction unit adds the correction value to an electrical signal output from the imaging element.   The image pickup apparatus according to claim 2 or 3, wherein the image pickup device amplifies and outputs the accumulated electric charge according to the sensitivity set by the sensitivity setting means. An image processing apparatus that processes an electrical signal output from an imaging apparatus having an imaging element,
Obtaining means for obtaining an electrical signal from the imaging device;
An image processing apparatus comprising: a correction unit that corrects the electrical signal acquired by the acquisition unit in accordance with charge transfer efficiency in the imaging device. An image processing apparatus that processes an electrical signal output from an imaging apparatus having imaging elements capable of imaging with different sensitivities,
A sensitivity acquisition means for acquiring sensitivity at the time of imaging;
Correction value acquisition means for acquiring a correction value according to the charge transfer efficiency in the image sensor at the acquired sensitivity;
An image processing apparatus comprising: a correction unit that corrects an electrical signal output from the image sensor using the correction value acquired by the correction value acquisition unit.   The image processing apparatus according to claim 10, wherein the charge transfer efficiency in the image pickup device is a charge amount lost during charge transfer in the image pickup device. A signal processing method for processing an electrical signal output from an imaging device having an imaging element,
An acquisition step of acquiring an electrical signal from the imaging device;
And a correction step of correcting the electrical signal acquired in the acquisition step according to the charge transfer efficiency in the image pickup device. A signal processing method for processing an electrical signal output from an imaging device having imaging elements capable of imaging with different sensitivities,
A sensitivity acquisition step for acquiring sensitivity at the time of imaging;
A correction value acquisition step of acquiring a correction value according to the charge transfer efficiency in the image sensor at the acquired sensitivity;
And a correction step of correcting an electric signal output from the image sensor using the correction value acquired in the correction value acquisition step.   In the correction value acquisition step, the correction value corresponding to the sensitivity acquired in the sensitivity acquisition step among the correction values corresponding to the charge transfer efficiency in the image sensor for each different sensitivity stored in the storage unit in advance is stored in the storage unit. The signal processing method according to claim 13, wherein the signal processing method is obtained from a means. The correction value acquisition step includes
A reference correction value acquisition step of acquiring a reference correction value according to the charge transfer efficiency in the imaging device at a predetermined reference sensitivity;
And a calculation step of calculating a correction value according to the set sensitivity based on the sensitivity acquired in the sensitivity acquisition step and the reference correction value acquired in the reference correction value acquisition step. The signal processing method according to claim 13.   The signal processing method according to claim 12, wherein the charge transfer efficiency in the image pickup device is a charge amount lost during charge transfer in the image pickup device.   16. The signal processing according to claim 15, wherein in the calculation step, a correction value is calculated based on the reference correction value according to a ratio between the reference sensitivity and the sensitivity acquired in the sensitivity acquisition step. Method.   16. The method according to claim 15, further comprising a control step of controlling not to perform correction by the correction step when the sensitivity acquired in the sensitivity acquisition step is lower than a predetermined sensitivity lower than the reference sensitivity. The signal processing method according to claim 17.   The signal processing method according to claim 12, wherein, in the correction step, the correction value is added to an electrical signal output from the imaging device.   A program executable by an information processing apparatus, comprising program code for realizing the signal processing method according to claim 12.   A storage medium readable by an information processing apparatus, wherein the program according to claim 20 is stored.

Images