JP2002281389A - Imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate influence of reverse incident light through an eyepiece shutter at defect detection and to cope with degradation of a defect of pixel over aging without generating erroneous detection. SOLUTION: In this imaging system having a defect data detecting part to detect a pixel defect address by analyzing image pickup output to be obtained at a state that incident light on an image pickup device 202 is shielded and a defect compensating part to perform a compensation processing by adjacent image data to the output of the image pickup device 202 based on the detected defect data, it is constituted so that acquisition of defect data is allowed only when the eyepiece shutter 211 is closed by providing the eyepiece shutter 211 to shield incidence of light from a finder opening to the image pickup device 202.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an imaging device such as an electronic still camera (digital camera) or a video camera, and more particularly to an imaging device having a pixel defect compensation function.

[0002]

2. Description of the Related Art In recent years, electronic still cameras have been developed mainly for capturing and recording still images. In addition, a video camera for recording a moving image is provided with a still image recording function. When a still image is captured by these cameras, a so-called long-time exposure technique in which the exposure time is lengthened by lengthening the charge accumulation time in the image sensor is employed. With this long-time exposure technique, it is possible to take a picture even under low illuminance without using auxiliary lighting such as a strobe.

On the other hand, in the image pickup device, there is a dark output due to a so-called dark current or the like, and there is a problem that the dark output is superimposed on an image signal to deteriorate the image quality. The presence of a pixel having a high dark output level is called a pixel defect, and it is widely practiced to supplement the information using the output information of neighboring pixels without using the output information of the pixel. In this specification, such a complementing process is referred to as pixel defect compensation. As an example, a predetermined (N
In TSC, the dark output is evaluated at the standard exposure time of 1/60 second or 1/15 second when a predetermined margin is obtained based on the predetermined margin (based on the predetermined margin). Pixels having a large level are evaluated as defective pixels. There is an example in which the above-mentioned pixel defect compensation is applied.

Further, an image pickup device has been proposed which has been improved in that the evaluation of defective pixels is not sufficient just before shipment from the factory because pixel defects are accompanied by temperature dependence and changes with time (Japanese Patent Application Laid-Open No. HEI 9-163568). 6-38113). That is, this publication discloses that the light receiving surface is shielded from light by closing the iris immediately after the power is turned on, a defective pixel is detected by evaluating a CCD dark output prior to use of the camera, and information on the detected defective pixel is used. A technology for compensating for defects is described.

[0005]

However, in this type of method, a defective pixel may be erroneously detected by back-incident light from a single-lens reflex optical viewfinder. In a digital camera, a prism type half mirror is often used to realize a single-lens reflex camera. In this case, the light incident from the aperture of the finder system goes back through the finder optical path as it is, and the reverse incident light passes through the half mirror, is reflected at the end of the prism, and is incident on the image sensor when reflected again by the half mirror. . Then, the reverse incident light is superimposed on the original imaging signal, which causes erroneous detection.

[0006] This effect is particularly large in the case of defect detection. That is, in the case of defect detection, the dark current is detected in a light-shielded state, and therefore, the influence of light from a part not shielded is large. In addition, once detected, it is considered that there is always a defect thereafter, so the effect is even greater.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to eliminate the possibility of erroneous detection of defects due to back-incident light from the finder opening and to increase pixel defects over time. An object of the present invention is to provide a high-performance imaging device that does not cause deterioration in image quality.

[0008]

(Structure) In order to solve the above problem, the present invention employs the following structure.

That is, the present invention provides an image pickup device, an image pickup device for picking up a subject image, a storage unit for registering a pixel defect address of the image pickup device as defect data, and the storage unit for an output of the image pickup device. Defect compensation means for performing compensation processing based on neighboring pixel data based on the defect data registered in the image sensor, and analyzing the output of the image sensor obtained in a state where light incident on the image sensor is cut off, thereby analyzing the pixel defect address. Defect data detection means for newly detecting the defect data, and defect data management means for updating the defect data registered in the storage means based on the defect data newly detected by the defect data detection means. It is characterized by.

Here, preferred embodiments of the present invention include the following. (1) When the setting state of the reverse incident light blocking means is switched to the blocking state, detection of a defective address by the defective data detecting means is performed.

(2) Storage means for registering a pixel defect address of the image sensor as defect data, and defect data for updating the defect data registered in the storage means based on the defect data newly detected by the defect data detection means. Having management means.

(3) The defect data management means, for the registered defect data which has already been registered, a pixel defect address of newly detected defect data which is newly detected and which does not overlap with a pixel defect address of the registered defect data. Must be configured to additionally register

(4) The defect data management means compares the initially registered defect data registered at the time of factory shipment with the pixel defect address of the initially registered defect data among the pixel defect addresses of newly detected defect data newly detected. It must be configured to additionally register non-overlapping items.

(Operation) According to the present invention, a defect data detecting means for detecting a pixel defect address by analyzing an output of an image pickup device obtained in a state where light incident on the image pickup device is blocked, In an imaging apparatus having a defect compensation unit that performs compensation processing based on data on the output of the imaging device with neighboring pixel data, a reverse incident light blocking unit that blocks light incident from the finder opening to the imaging device is provided, A setting state detecting means for detecting a setting state of the reverse incident light blocking means is provided, and when the setting state of the reverse incident light blocking means is not in the blocking state, detection of a defect address by the defect data detecting means is prohibited. Accordingly, it is possible to prevent erroneous detection from occurring due to reverse incident light from the finder opening when detecting a pixel defect. This makes it possible to provide a high-performance imaging device that does not cause image quality degradation due to an increase in pixel defects over time.

Further, by providing a storage means for registering a pixel defect address as defect data and a defect data management means for updating the defect data registered in the storage means based on newly detected defect data, The registered defect data has a temporal pixel defect caused by the influence of cosmic rays and natural radioactivity in addition to the initial pixel defect at the time of factory shipment. Therefore, by performing the compensation process using the neighboring pixel data based on the defect data registered in the storage unit, it is possible to prevent the image quality from deteriorating due to an increase in pixel defects over time. Further, by performing this additional registration at a low frequency by the clock function of the self, the detection operation becomes unnecessary at the time of normal photographing, so that no time lag occurs. In addition, since the defect data is regularly updated, the defect is not left out, so that it is possible to effectively prevent the defect from appearing.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments.

(Embodiment) FIG. 1 is a block diagram showing a basic configuration of a digital camera according to an embodiment of the present invention.

In FIG. 1, reference numeral 101 denotes a lens system including various lenses, and reference numeral 102 denotes a lens driving mechanism for driving the lens system 101. Reference numeral 103 denotes an exposure control mechanism for controlling the exposure, which includes an aperture and a drive mechanism for driving the aperture, and is provided for controlling the aperture by limiting the amount of incident light of light rays passing through the lens system 101. I have. Reference numeral 104 denotes a filter system having a filter for low-pass and infrared cut, and reference numeral 105 denotes a CCD color image sensor. Light rays that have passed through the exposure control mechanism 103 are guided to the image sensor 105 via the filter 104. Therefore, an image corresponding to the subject is formed on the image sensor 105.

107 is a gain control amplifier, A
A pre-processing circuit including a / D converter and the like. An imaging signal obtained by the imaging element 105 is input to the pre-processing circuit 107, and a digitized pixel signal is output from the pre-processing circuit 107. Reference numeral 108 denotes a digital process circuit for performing a color signal generation process, a matrix conversion process, and other various digital processes. The digital process circuit 108 generates color image data by processing the digitized image signal. Is done. 109 is a card interface connected to the digital process circuit 108, and 110 is a CF (Co)
mpact Flash Memory Card) or a memory card such as a smart media, and 111 is an LCD image display system. The memory card 110 stores color image data, and the LCD display system 111 displays color image data.

In the figure, reference numeral 112 denotes a system controller (CPU) for comprehensively controlling each unit, 113 denotes an operation switch system composed of various SWs, and 114 denotes an operation display for displaying an operation state, a mode state, and the like. System, 115 is a lens driver for controlling the lens driving mechanism 102, 116 is a strobe as a light emitting means, 117 is an exposure control driver for controlling the exposure control mechanism 103 and the strobe 116, and 118 is various kinds of setting information and the like. 1 shows a non-volatile memory (EEPROM) for performing the operation. Here, the image defect data is stored in advance in the EEPROM 118 together with various setting information and the like.

Further, reference numeral 120 in the drawing denotes a detection switch for detecting the setting state of the reverse incident light blocking means described later.

In the digital camera of the present embodiment, the system controller 112 performs overall control, and in particular, a shutter device included in the exposure control mechanism 103 and the CCD image pickup device 10 by the CCD driver 106.
5, the exposure (charge accumulation) and the signal readout are performed by controlling the driving of the pixel 5, and the detection of the pixel defect described below is performed using the output level information stored in the digital process 108 via the preprocess 107. Is what you do.

FIG. 2 is a diagram showing the configuration of the image pickup unit and the configuration of the finder unit in the camera according to the present embodiment.

The incident light is guided to the CCD image pickup device 202 (105 in FIG. 1) by the image pickup lens system 201 (101 in FIG. 1) provided in the camera housing 200, and the subject image is projected on the light receiving surface of the image pickup device 202. It is imaged. A prism type half mirror 20 is provided between the lens system 201 and the image sensor 202.
3 is installed, and a part of the incident light from the lens system 201 is reflected by the half mirror 203. The light reflected by the half mirror 203 is reflected by the mirror 204 and guided to the finder opening via the lenses 205 and 206.

The configuration of the image pickup unit and the finder unit up to this point is the same as that of a normal device, but in this embodiment, in addition to this, a reverse incident light blocking unit for blocking incident light from the finder opening is provided. Have been. This reverse incident light means is formed by a light shielding plate 211, a shaft body 212 and a lever 213. The shaft 212 is provided rotatably through the camera housing 200. A light-shielding plate 211 is attached to the end of the shaft 212 inside the camera, and the light-shielding plate 211 shields the finder opening by the rotation of the shaft 212. That is, the outermost lens 2 of the opening of the optical finder
A light-shielding plate (eyepiece shutter) 211 made of a matte-black painted resin plate is installed inside the inside of the cover 06. The lever 21 is attached to the outer end of the shaft 212 at the camera.
3 is formed integrally, and the shaft 212 is rotated by operating the lever 213.

A section 215 is fixed to the camera inner end of the shaft 212, and an electrical contact (mechanical switch) 230 (12 in FIG. 1) is located adjacent to the section 215.
0) is provided. In a state where the lever 213 is set vertically, as shown in FIG. 3A, the shielding plate 211 does not block the optical path. At this time, the section 230 is set to the switch 230.
5 does not touch, and the switch 230 is off. When the lever 213 is moved and inclined, the shielding plate 211 blocks the optical path, as shown in FIG. 3B. At this time, the section 215 presses the switch 230, and the switch 230 is turned on.

That is, the finder opening can be opened and closed by turning the lever 213, and this open / closed state can be detected by the switch 230.

FIG. 4 is a block diagram functionally showing a configuration relating to defect detection and defect compensation in the present embodiment. Reference numeral 401 denotes an EEPROM for storing defect data;
2 is a pixel defect compensation unit, 403 is a defect data detection unit,
Reference numeral 404 denotes a defect data management unit. These are realized by controlling the digital process circuit 108 and the EEPROM 118 under the control of the system controller 112.

The EEPROM 401 is the EEPROM 1
The EEPROM 401 stores address data related to existing (latest) defect data (hereinafter referred to as registered defect data). Initially (when the camera is shipped from the factory), defect data acquired in the manufacturing adjustment process is registered as a registered defect.

The defect compensating means 402 performs a supplementary process for defective pixels by neighboring pixels.
02, an EEPROM is used for the input image data.
The registered defect data stored in 401 is read, and pixel defect compensation processing such as adjacent complementation is performed based on the defect data. The defect data detection means 403 newly detects a pixel defect address by analyzing the output of the image sensor obtained in a state in which light incident on the image sensor is blocked. Then, the defect data management unit 404 uses the EEPROM 401 based on the newly detected defect data.
The defect data registered in is updated.

Hereinafter, the imaging operation in the present embodiment, particularly the processing relating to the detection and compensation of pixel defects and the processing for preventing malfunction due to back-incident light from the finder opening will be specifically described. Here, it is assumed that digital processing of the signal level is performed by 8 bits (0 to 255) in the present camera. Also, description will be made assuming normal temperature, except for the parts described later.

First, processing relating to detection and compensation of a pixel defect will be described. Prior to photographing, an exposure time required for photographing is set based on a manual setting or a photometric result. Next, the camera waits for a shooting trigger command for the main imaging, and upon receiving the command, performs exposure based on a predetermined exposure control value, reads out an imaging signal, performs predetermined signal processing, and then performs memory processing on the memory card 11.
Record at 0. At this time, the registered defective pixel is accompanied by pixel defect compensation. The video signal processing up to the recording after the defect compensation is appropriately used according to its necessity. The video signal processing is known per se, for example, a color balance processing, a conversion into a luminance-color difference signal by a matrix operation or a reverse conversion processing thereof, Examples include false color removal or reduction processing by band limitation, various nonlinear processing represented by gamma conversion, various information compression processing, and the like.

In this camera, the defect compensation employs the well-known “complementation of a pixel in which a defect address is registered with a neighboring pixel”. 4 closest to the defective pixel
Pixels: In the case of an RGB Bayer array, for example, four G pixels adjacent diagonally in four directions for G, and one G between R (or B) instead of directly adjacent in four directions of up, down, left, and right
Is used instead of the average value of the four pixel information corresponding to the four R (or B) pixels located next to each other.

The camera detects a defect when necessary, and additionally updates the registered defect based on the result. The defect detection is performed as follows. FIG. 5 shows a flowchart in this case.

First, the light receiving surface of the image sensor 105 is shielded from light by a shutter device included in the exposure control mechanism 103 (S
1) Test imaging is performed in the light-shielded state (S2). That is, the longest exposure time Tmax of the present camera is set by the CCD driver 106 in the dark (setting is arbitrary: the example value 5 s here).
Test charge signal (dark output signal)
Is read and stored in the digital process 108 (S
3). Each output level is checked for all the stored data of the effective output pixels, and a digital comparison with the reference level is performed to determine whether or not the data is defective (S4).

The criteria are as follows. That is, if the output level of the target pixel is P, the defect is determined when P> 5, and the defect is determined to be non-defect otherwise (P ≦ 5). This means that the dark output level at the time of main imaging is allowed up to about 2% of the maximum full range 255.

Here, the judgment reference level of about 2% is merely an example, and can be set arbitrarily according to circumstances at the time of design. If an appropriate value of the above level (for example, about 5% or about 1% is also effective) is selected, the possibility that the effect of the dark output superimposed on the image becomes apparent becomes sufficiently low. If this is selected to be 0%, it is possible to completely eliminate the pixel on which the dark output is superimposed. In this respect, this can be cited as a preferred embodiment. On the contrary, this means that the pixel information is completely discarded due to the superimposition of a slight dark signal, and therefore, the overall image quality may be reduced. In reality,
The reference level is set in consideration of these trade-off factors.

The specific steps after step S4 are as follows. First, after designating the first address (S5), it is determined whether or not P> 5 for this address (S6). If P> 5 is determined in step S6, it is determined that there is a pixel defect (S7), and the address of the detected pixel defect is temporarily stored (S8). Step S6
If it is determined that P ≧ 5, it is determined that there is no defect (S9). Then, it is determined in step S10 whether the address is the last address (S10). If the address is not the last address, the next address is specified (S11), and the process returns to step S6. If it is determined in step S10 that the address is the last address, the address of the temporarily stored pixel defect is stored in the EEPROM 201.
(S12).

When updating the defective data in the EEPROM 401, the address of the detected defective pixel from which the duplicate with the registered defect has been removed is additionally registered. At this time,
The configuration may be such that the data of the detected defect is simply replaced with the existing registration data. However, in this case, if a detection error occurs due to some cause such as noise at the time of new detection, a pixel which was defective due to deterioration over time at the time of shipment from the factory is treated as a non-defect, and the defect becomes apparent. There is a possibility that it will be done. On the other hand, in the present embodiment, a defect obtained by removing the overlap with the existing registered defect from the detected defect is added to the existing data. Therefore, there is an effect that the once registered defect can be prevented from reappearing. are doing.

Updating of the data (detection of the defect and additional update of the registered defect) is performed based on the clock function of the camera. In this embodiment, the update time is set once a day at 2:00 midnight. Then, when the update time comes, the data is updated when the power is turned on for the first time and the finder opening is closed. At that time, it is preferable to display a display such as “Camera is being set up” in an appropriate place, for example, on an electronic view finder by the LCD 111 in order not to confuse the user.
Thereafter, the data is not updated until the next update time comes, so that there is no time lag on the day. Further, since the data is not updated unless the power is turned on, useless power is not consumed.

Next, a description will be given of a process for preventing malfunction due to back-incident light from the finder opening. When detecting the above-mentioned defective pixel, it is detected whether or not the finder opening is closed by the light shielding plate 211. If the finder opening is closed, detection of defective pixels and update of defective pixel data are performed as described above. If the finder opening is not closed, detection of a defective pixel and updating of data are not performed. At this time, a message such as "Please close the eyepiece shutter" may be displayed on the LCD 111 to urge the user to close the optical finder, and confirm that the optical finder has been closed, and then proceed to the detection of a pixel defect.

As described above, according to the present embodiment, the light shielding plate 2
11 to detect the open / close state of the finder opening, detect the defective pixel and update the defective pixel data if the finder opening is closed, and prohibit the detection of the defective pixel if not closed. Therefore, it is possible to prevent erroneous detection due to reverse incident light from the finder opening when detecting a pixel defect.

In the present embodiment, the defect data registered in the EEPROM 401 is updated based on the newly detected defect data, so that the defect data registered in the EEPROM 401 is added to the initial pixel defect at the time of shipment from the factory. It has a temporal pixel defect. Therefore, EE
By performing compensation processing using neighboring pixel data based on the defect data registered in the PROM 401, it is possible to prevent image quality deterioration due to an increase in pixel defects over time.

(Modification) As a modification, the data may be updated when the mechanical switch is turned on (that is, when the eyepiece shutter is switched to the light blocking state) instead of "power on". Good.

As another modified example, there is one in which data is updated when an update time comes when the power is not turned on. For example, when the update time comes at 2 o'clock at midnight, once every three days, the internal power supply of the camera may be turned on by itself, the ON of the mechanical switch may be confirmed, and the data may be updated. In this case, the update is generally performed infrequently during the time when the camera is unlikely to be used, so that the possibility of affecting the user is extremely small, and the user is almost always used. Can be used without time lag. In this case, if there is a manual command to turn on the power during the data update, the update operation is immediately stopped, and the priority is given to the normal shooting function, so that the time lag can be completely eliminated. is there.

Further, in any of the above-mentioned examples, it is more preferable that the user can arbitrarily change the setting of the renewal time because the degree of freedom is increased. Furthermore, instead of setting the update timing at regular intervals, random irregular time intervals may be set, or time management using a clock may be performed. The renewal time can be set based on numerical information such as once every time. However, since the temporal change of the pixel defect is usually a stochastic phenomenon, the periodic time management as in the above embodiment is more preferable.

In addition, if supplementation is made regarding the quantization level of the A / D converter used in the embodiment, in reality, A
If there is an error characteristic of the / D converter hardware, or even if it does not exist, the quantization error is relatively equivalent to 100% in principle near the minimum quantization level. Considering this, the A / D converter used for actual quantization in the above embodiment is larger than the number of quantization bits (8 bits in the embodiment) of the image processing system, for example, about 10 bits or 12 bits (more than that). It is more preferable to use the method of (1), which can sufficiently reduce the influence of errors in the calculation of each of the above arithmetic expressions.

Although several examples have been specifically described as the embodiments and the modified examples of the present invention, the present invention is not limited to these, and can take any form as long as it is described in the claims. Needless to say,

[0049]

As described above in detail, according to the present invention, there is provided a defect data detecting means for detecting a pixel defect address by analyzing an output of an image pickup device obtained in a state where light incident on the image pickup device is blocked. In an image pickup apparatus having a defect compensating means for performing a compensation process based on detected defect data on an output of an image pickup element using neighboring pixel data, a reverse incident light block for blocking light incidence from the optical finder means to the image pickup element. Means, and setting state detecting means for detecting the setting state of the reverse incident light blocking means, and when the setting state of the reverse incident light blocking means is not in the blocking state, detection of a defect address by the defect data detecting means. , Which eliminates erroneous detection due to back-incident light from the finder and prevents image quality degradation due to the increase in pixel defects over time. It is possible to realize an imaging apparatus.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a digital camera according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of an imaging unit and a finder unit according to the embodiment.

FIG. 3 is a diagram showing an open / closed state of a finder opening by rotation of a lever.

FIG. 4 is a block diagram functionally showing the configurations of a defect detection unit and a compensation unit according to the embodiment.

FIG. 5 is a flowchart for explaining pixel defect detection and defect address update.

[Explanation of symbols]

 101, 201 ... Lens system 102 ... Lens drive mechanism 103 ... Exposure control mechanism 104 ... Mechanical shutter 105,202 ... CCD color image sensor 106 ... CCD driver 107 ... Pre-process circuit 108 ... Digital process circuit 109 ... Card interface 110 ... Memory card 111 ... LCD image display system 112 ... System controller (CPU) 113 ... Operation switch system 114 ... Operation display system 115 ... Lens driver 116 ... Strobe 117 ... Exposure control driver 118 ... Non-volatile memory (EEPROM) 200 ... Camera housing 203 ... Half Mirror 204 Mirror 205, 206 Finder lens 211 Shield plate 212 Shaft 213 Lever 215 Section 230 Switch 401 EEPROM 402 Pixel defect compensation means 403: defect data detection means 404: defect data management means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hideaki Yoshida 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industrial Co., Ltd. F-term (reference) 5C022 AA13 AB37 AC02 AC08 AC09 AC69 CA00 5C024 BX01 CX22 CX23 CX24 EX41 EX47 GY01 HX14 HX29 HX51 HX58

Claims (5)

[Claims] An image pickup device for picking up a subject image, an image pickup optical system for inputting a subject image to the image pickup device, and an image pickup light blocking unit for blocking incident light from the image pickup optical system to the image pickup device; Optical finder means for confirming the subject by branching a part of the light incident on the image sensor, and reverse incident light blocking means for blocking light from the optical finder means to the image sensor, A setting state detecting means for detecting a setting state of the reverse incident light blocking means, and an output of the image pickup element obtained in a state in which light incident on the image pickup element by the image pickup optical system is blocked by the image pickup light blocking means is analyzed. Defect data detecting means for detecting the pixel defect address, and complementing the output of the image sensor with neighboring pixel data based on the defect data detected by the defect data detecting means. A defect compensating means for performing processing, and a control means for inhibiting detection of a defect address by the defect data detecting means when the setting state of the reverse incident light blocking means detected by the setting state detecting means is not in the blocking state. An imaging device comprising: 2. The apparatus according to claim 1, wherein when the setting state of said reverse incident light blocking means is switched to a blocking state, detection of a defective address by said defect data detecting means is executed. 2. The imaging device according to 1. 3. A storage unit for registering a pixel defect address of the image sensor as defect data, and updating the defect data registered in the storage unit based on the defect data newly detected by the defect data detection unit. The imaging apparatus according to claim 1, further comprising defect data management means. 4. The defect data management means according to claim 1, wherein said registered defect data is a pixel defect address of newly detected defect data which does not overlap with a pixel defect address of registered defect data. The imaging apparatus according to claim 3, wherein the imaging device is configured to additionally register the image. 5. The defect data management means according to claim 1, wherein said initial registered defect data registered at the time of shipment from the factory is replaced with a pixel defect address of said newly registered defective data among pixel defect addresses of newly detected defective data. 4. The imaging apparatus according to claim 3, wherein a non-overlapping one is additionally registered.