JP2009296134A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a release time lug and an image loss (blackout) period. <P>SOLUTION: When an imaging mode is changed over from a first imaging mode to a second imaging mode, a read control part 5 controls an imaging element 1 so that the imaging element 1 outputs a signal used for correcting a signal output in the second imaging mode before the start of the second imaging mode. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus that captures an image.

  Conventionally, as a method of correcting an image captured by a digital camera, an image sensor that outputs a captured image, a mechanical shutter that can shield the light receiving surface of the image sensor, and an image capturing operation with an exposure time longer than a predetermined time are performed. After that, a technique is known in which a dummy imaging operation is appropriately performed according to an exposure time in a state where the mechanical shutter is operated to shield the light receiving surface of the imaging element, and the image quality of the captured image is corrected using the dummy imaging data. (For example, refer to Patent Document 1).

Also, control is performed to acquire the first and second correction data immediately before and after imaging exposure for acquiring imaging data, and imaging is performed using the correction data, the acquisition time, and the imaging exposure time as parameters. A method of calculating an actual correction amount within the exposure time is also known (see, for example, Patent Document 2). In addition, a method for removing or reducing fixed pattern noise using an output signal for one horizontal scanning line in an optical black region of a solid-state imaging device is known (for example, see Patent Document 3).
JP 2000-125204 A Japanese Patent Laid-Open No. 10-208016 JP 2004-208240 A

  However, in the correction processing of the captured image using the above method, there are problems that the release time lag and the image loss (blackout) period increase. Also, in recent years, while the high-speed frame rate of imaging has been increasing, the optical black (OB) region generally used for correction processing and the like has been reduced, and correction processing can be performed only with the OB region of the solid-state imaging device. There is a limit. Further, when the number of readout pixels is increased for correction with priority on correction processing, a high-quality image can be obtained, but there is a problem that a release time lag and blackout increase.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an imaging apparatus capable of shortening a release time lag and an image loss (blackout) period and capable of imaging at high speed. To do.

  The present invention can operate in a plurality of imaging modes having different imaging conditions, and outputs an image signal corresponding to each imaging mode, and the imaging mode from the first imaging mode to the second imaging mode. A controller for controlling the image sensor so that a signal used for correcting the signal output by the image sensor in the second imaging mode is output before the start of the second imaging mode. An imaging apparatus including the imaging apparatus.

  In addition, the present invention includes an image processing unit that corrects a signal output in the second imaging mode based on a signal used for the correction output by the imaging element before the start of the second imaging mode. This is an imaging apparatus.

  In addition, the present invention includes a mechanical shutter capable of shielding the light receiving surface of the image sensor, and the image sensor is the second when the mechanical shutter shifts from a light shielding state to an exposure state or from an exposure state to a light shielding state. The image pickup apparatus is characterized in that the control unit controls the image pickup element so that a signal used for correcting a signal output in the image pickup mode is output before the start of the second image pickup mode.

  In the imaging apparatus of the present invention, the imaging mode includes a display image imaging mode in which the imaging element outputs a display signal with a small number of pixels, and a high-resolution signal with a large number of pixels. And a screen image capturing mode.

  According to the present invention, the release time lag and the image loss (blackout) period can be shortened.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram illustrating the configuration of the imaging apparatus according to the present embodiment. The imaging device includes an imaging device 1, an image processing unit 2, an image output unit 3, an image display unit 4, a read control unit 5, a system control unit 6, a timing generator 7, and a memory 8.

  The image sensor 1 converts light (optical image) incident on a light receiving surface composed of an effective pixel region and an OB (optical black) region into an electrical signal (analog image signal) by photoelectric conversion, and outputs the signal. The image processing unit 2 converts the analog image signal output from the image sensor 1 into a digital image signal. The image processing unit 2 performs image processing on the digital image signal. The image output unit 3 performs control to display the image signal that has been subjected to image processing by the image processing unit 2 as an image on the image display unit 4. The image display unit 4 displays an image. The read control unit 5 controls a signal read by the image sensor 1. The system control unit 6 controls the entire imaging apparatus. The timing generator 7 generates a timing signal that defines the operation timing of each unit in the imaging apparatus, and sends it to the imaging device 1, the image processing unit 2, the image output unit 3, the image display unit 4, and the system control unit 6. The generated timing signal is input. The memory 8 stores a digital image signal.

  Next, with reference to FIG. 2, the timing of the signal output from the image sensor 1 and the image of the output image will be described. Here, “Valid” in the figure represents image data in the valid period, and “V BLANK” represents the blanking period in the vertical scanning period.

  In the illustrated example, in the conventional imaging device, OB (Optical) used for correction of the live view image is performed before the live view (LV) image is output (imaging mode for outputting the live view image (display image capturing mode)). (Black) The read controller controls the image sensor so as to output an image. Also, before outputting a still (single-shot) image (an imaging mode for outputting a still image (full-screen image imaging mode)), reading is performed so as to output FPN (fixed pattern noise) correction data used for correcting still image data. The control unit controls the image sensor.

  The display image capturing mode is an image capturing mode in which the image sensor outputs a display signal with a small number of pixels. The full-screen image capturing mode is an image capturing mode in which the image sensor outputs a high resolution signal having a large number of pixels. In addition, the live view image is continuously output at a predetermined frame rate.

  On the other hand, in the imaging apparatus of the present embodiment, the read control unit 5 controls the imaging element 1 so that FPN correction data is output before the output of the live view image (display image capturing mode). Further, the read control unit 5 controls the image sensor 1 so that only the OB image is output before the still image (full-screen image capturing mode).

  As a method for changing the imaging mode, for example, when a release button (not shown) is pressed, the read control unit 5 outputs a still image from an imaging mode (display imaging mode) for outputting a live view image. The image sensor 1 is controlled to change the imaging mode to the imaging mode to be performed (full-screen image imaging mode). Further, after capturing in the full screen image capturing mode, the readout control unit 5 controls the image sensor 1 so as to change the capturing mode to the display image capturing mode.

  Next, in the present embodiment, a timing of a signal output from the image sensor 1 and a timing at which the image processing unit 2 generates display data (live view image or still image) will be described. FIG. 3 is a diagram illustrating the timing at which the imaging device 1 outputs a signal and the timing at which the image processing unit 2 outputs display data in the present embodiment and the conventional imaging device.

  In the example shown in the figure, an image processing unit used in a conventional imaging device corrects the live view image using the OB image output by the imaging device before outputting the live view image, and displays the display data. Output. Further, the still image is corrected using the FPN correction data output from the image sensor before the still image is output, and the display data is output.

  On the other hand, the image processing unit 2 used in the imaging apparatus according to the present embodiment corrects the live view image and the still image based on the FPN correction data output from the imaging device 1 before the live view image is output. Generate data. Thereafter, when the imaging device 1 outputs a live view image, the image processing unit 2 corrects the live view image using the generated correction data. When the image sensor 1 outputs an OB image and a still image, the image processing unit 2 corrects the still image using the generated correction data and the OB image. In the illustrated example, the image processing unit 2 corrects the still image M using the correction data N and the OB image M.

  Note that the image processing unit 2 further performs BAYER conversion, resizing processing, and the like in order to make a still image corrected using the correction data and the OB image suitable for display on the image display unit 4. Image processing such as gamma correction may be performed. Further, as a method of generating the correction data by the image processing unit 2, the correction data may be generated by performing an integration process for each line or by performing an integration process for each frame. In general, it has been clarified that the correction effect can be obtained and the random noise can be reduced as the number of pixels of the correction data increases.

  As described above, according to the present embodiment, the read control unit 5 controls the image sensor 1 to output FPN correction data for correcting a still image immediately before outputting a live view image. The image processing unit 2 generates correction data for correcting the still image based on the FPN correction data.

  That is, the image sensor 1 outputs correction data for correcting a still image output in the full screen image capturing mode before switching from the display image capturing mode to the full screen image capturing mode, and the image processing unit 2. Performs correction of a still image using the correction data.

  Thereby, the read control unit 5 does not need to control the image sensor 1 so as to output the FPN correction data during the full screen image capturing mode. Therefore, it is possible to shorten the time (release time lag) from when the image processing unit 2 outputs the live view image to when the still image optimally subjected to the correction process is output (release time lag).

  In the present embodiment, in the still image correction processing, the image processing unit 2 uses the correction data generated based on the FPN correction data output immediately before the image sensor 1 outputs the still image M. Although the correction has been performed, the image processing unit 2 performs a process such as cumulative addition or averaging on a plurality of pieces of correction data N-1, N-2,. And the still image M may be corrected using the generated correction data.

  In the present embodiment, in the still image correction processing, the image processing unit 2 uses the correction data generated based on the FPN correction data output immediately before the image sensor 1 outputs the still image M. Although the correction has been performed, the image processing unit 2 stores a plurality of correction data generated based on the FPN correction data in the memory 8, and uses correction data optimal for correcting the still image M among the stored correction data. The still image M may be corrected.

  Further, although the still image correction method has been described, in the present embodiment, the live view image can be corrected in the same manner. FIG. 4 is a diagram illustrating a timing at which the image sensor 1 outputs a signal and an image to be output in the imaging apparatus according to the present embodiment.

  In the illustrated example, in the imaging apparatus according to the present embodiment, the read control unit 5 controls the imaging element 1 so that the imaging element 1 outputs an OB image before the still image (full-screen image imaging mode). . Further, the read control unit 5 controls the image sensor 1 so that the image sensor 1 outputs an OB image before the live view image is output (display image capturing mode).

  In the present embodiment, the live view image is corrected based on the OB image output before the still image and the OB image output before the live view image. In the illustrated example, the image processing unit 2 corrects the live view image output in the frame Q based on the OB image output in the frame M and the OB image output in the frame Q.

  Conventionally, when the mode is switched from the full-screen image capturing mode to the display image capturing mode, the live view image is corrected based only on the OB image after the mode is switched. For this reason, since the image processing unit 2 cannot sufficiently output correction data such as an OB image, several tens of frames are required after mode switching in order to perform satisfactory correction.

  In the present embodiment, the imaging conditions (frame rate and thinning rate) between the OB image output before the full screen image capturing mode (frame N) and the OB image (frame Q) output after the full screen image capturing mode. Etc.) are the same, the OB image output before the full screen image capture mode (frame N), the OB image output after the full screen image capture mode (frame Q), and the full screen image. Based on the OB image output during the imaging mode (frame M), the live view image output after the full screen image imaging mode (frame Q) is corrected.

  As a result, the image processing unit 2 can quickly correct the live view image, so that the period until the image display unit 4 displays the live view image (image loss period) can be shortened.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a configuration diagram illustrating the configuration of the imaging apparatus according to the present embodiment. The imaging device includes an imaging device 1, an image processing unit 2, an image output unit 3, an image display unit 4, a readout control unit 5, a system control unit 6, a timing generator 7, a memory 8, and a shutter unit 9. Contains.

  The image pickup device 1, the image processing unit 2, the image output unit 3, the image display unit 4, the read control unit 5, the system control unit 6, the timing generator 7, and the memory 8 are the units shown in FIG. It is the same. The shutter unit 9 has a mechanical shutter and controls light reception of the image sensor 1.

Next, the output timing of the shutter unit 9 and the correction data in the present embodiment will be described with reference to FIG.
(Step S601) The imaging apparatus displays a live view image. At this time, the image sensor 1 outputs a live view image. The shutter unit 9 is in a released state (exposure state). In the open state, light enters the effective pixel area of the image sensor 1 and exposure is performed.

  (Step S602) After recognizing the still image acquisition instruction, the imaging apparatus captures an image from the imaging mode for outputting the live view image (display image imaging mode) to the imaging mode for outputting the still image (full-screen image imaging mode). Start mode change (light shielding preparation). At this time, the read control unit 5 controls the image sensor 1 so that the image sensor 1 outputs correction data used for correcting the still image. Moreover, the shutter part 9 is a state in the middle of shifting from the open state to the dark state (light shielding state). In this state, since a still image cannot be acquired, correction data is output using this time. As a method for recognizing a still image acquisition instruction, a method for recognizing a still image acquisition instruction when the second stage of a release button capable of setting a two-stage push-in state is set can be considered.

  (Step S603) After completion of the light shielding preparation, the imaging device acquires a still image. Specifically, when the preparation for light shielding is completed, the light receiving state of the image sensor 1 becomes a dark state in which light does not enter the light receiving surface, and a reset operation of the photodiode is performed to sweep out charges. Thereafter, by performing shutter scanning, an imaging operation (reading for main exposure) for a desired exposure time is performed, and a still image can be acquired. The image processing unit 2 corrects the still image using the correction data acquired in step S602. Note that correction data called dummy reading may be read before or after reading the imaging operation.

  (Step S604) After the acquisition of the still image is completed, the imaging apparatus changes the imaging mode from an imaging mode (full-screen image imaging mode) that outputs a still image to an imaging mode (display image imaging mode) that outputs a live view image. (Exposure preparation) is started. At this time, the read control unit 5 controls the image sensor 1 so that the image sensor 1 outputs correction data used for correcting the live view image. The shutter unit 9 is in the middle of shifting from the dark state to the open state. Since a live view image cannot be acquired in this state, correction data is output using this time.

  (Step S605) Similar to the processing in step S601, the imaging apparatus displays a live view image. At this time, the image sensor 1 outputs a live view image. Further, the shutter unit 9 is in a released state. The image processing unit 2 corrects the live view image using the correction data acquired in step S604.

  As a method for generating the still image correction data used in step S603, the correction data obtained at the timing of the still image correction data 0 and the still image correction data 2 shown in FIG. 6 and the correction data obtained in step S602 are obtained. Correction data may be generated in combination with the correction data acquired during the light shielding preparation. Further, as a method for generating correction data for live view images used in step S605, correction data obtained at the timing of live view image correction data 0 and live view image correction data 1 shown in FIG. Correction data may be generated by combining with the correction data acquired during exposure preparation acquired in S604.

  Next, the state of the shutter unit 9 when the imaging mode is changed from the display image imaging mode to the full screen image imaging mode and the output timing of the image output by the imaging element 1 will be described with reference to FIG. .

  In a camera equipped with a mechanical shutter, a light-shielding preparation time occurs when shifting from the display image capturing mode to the full screen image capturing mode. In the present embodiment, the read control unit 5 controls the image sensor 1 so that the image sensor 1 outputs correction data for an image acquired in the next imaging mode in accordance with the light shielding preparation time.

  In the example shown in the figure, correction data for a still image acquired in the full-screen image capturing mode that is the next imaging mode is acquired in accordance with the light shielding preparation time. In Example 7-1, a plurality of OB images are acquired. Further, in Example 7-2, dummy reading is performed in which the charge of the diode is not read while performing the same circuit operation as that for acquiring a still image.

  Next, the state of the shutter unit 9 when the imaging mode is changed from the full screen imaging mode to the display imaging mode and the output timing of the image output by the imaging device 1 will be described with reference to FIG. .

  In a camera equipped with a mechanical shutter, exposure preparation time occurs when shifting from the full-screen image capturing mode to the display image capturing mode. In the present embodiment, the read control unit 5 controls the image sensor 1 so that the image sensor 1 outputs correction data for an image acquired in the next imaging mode in accordance with the exposure preparation time.

  In the example shown in the drawing, correction data for a live view image acquired in a display image capturing mode that is the next image capturing mode is acquired in accordance with the exposure preparation period. In Example 8-1, a plurality of OB images are acquired. Further, in Example 8-2, dummy reading that does not read the charge of the diode is performed while performing the same circuit operation as that for obtaining the live view image.

  As described above, according to the present embodiment, the imaging device 1 outputs correction data while the shutter unit 9 is shifting from the open state to the dark state and during the transition from the dark state to the open state, and the image processing unit 2 is Based on the correction data, the still image is corrected and the live view image is corrected. That is, by reading the correction data during the light-shielding preparation period and the exposure preparation period, the image pickup apparatus according to the present embodiment acquires the next image pickup mode using the correction data while reducing the release time lag and the image loss time. By correcting the image to be corrected, it is possible to acquire an image with better image quality.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention. For example, in this embodiment, the image processing unit of the imaging apparatus corrects the still image. However, the still image and the correction data may be transferred to a personal computer and the still image may be corrected using the personal computer. Good.

1 is a configuration diagram illustrating a configuration of an imaging apparatus according to a first embodiment of the present invention. It is the figure which showed the timing which the image pick-up element in 1st embodiment of this invention and the conventional imaging device outputs a signal, and the image of the image output. It is the figure which showed the timing which the image pick-up element in 1st embodiment of this invention and the conventional imaging device outputs a signal, and the timing which an image process part outputs the data for a display. It is the figure which showed the timing which the image pick-up element in the imaging device by 1st embodiment of this invention outputs a signal, and the image of the image output. It is the block diagram which showed the structure of the imaging device by 2nd embodiment of this invention. It is the figure which showed the timing of the output of the shutter part in 2nd embodiment of this invention, and correction data. In the second embodiment of the present invention, it is a diagram showing the state of the shutter portion when the imaging mode is changed from the display imaging mode to the full screen imaging mode, and the output timing of the image output by the imaging device. is there. In the second embodiment of the present invention, it is a diagram showing the state of the shutter portion when the imaging mode is changed from the full screen imaging mode to the display imaging mode, and the output timing of the image output by the imaging device. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Imaging device, 2 ... Image processing part, 3 ... Image output part, 4 ... Image display part, 5 ... Read-out control part, 6 ... System control part, 7 ... Timing generator, 8 ... memory, 9 ... shutter unit

Claims (4)

An imaging device that can operate in a plurality of imaging modes with different imaging conditions and outputs a signal corresponding to each imaging mode;
When the imaging mode is switched from the first imaging mode to the second imaging mode, a signal used for correcting the signal output by the imaging element in the second imaging mode is output before the start of the second imaging mode. A control unit for controlling the image pickup device,
An imaging apparatus comprising: An image processing unit for correcting a signal output in the second imaging mode based on a signal used for the correction output by the imaging element before the start of the second imaging mode. Item 2. The imaging device according to Item 1. A mechanical shutter capable of shielding the light receiving surface of the image sensor;
When the mechanical shutter is in the exposure state from the light shielding state, or the transition from the exposure state to the light shielding state, a signal used for correcting a signal output by the imaging device in the second imaging mode is used before the second imaging mode is started. The image pickup apparatus according to claim 1, wherein the control unit controls the image pickup device so as to output to the image pickup device. The imaging mode includes a display image imaging mode in which the imaging element outputs a display signal with a small number of pixels, and a full-screen image imaging mode in which the imaging element outputs a high-resolution signal with a large number of pixels. The imaging apparatus according to any one of claims 1 to 3, wherein the imaging apparatus is characterized.

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