WO2013039061A1 - 撮像装置、撮像方法及び記録媒体 - Google Patents
撮像装置、撮像方法及び記録媒体 Download PDFInfo
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- WO2013039061A1 WO2013039061A1 PCT/JP2012/073184 JP2012073184W WO2013039061A1 WO 2013039061 A1 WO2013039061 A1 WO 2013039061A1 JP 2012073184 W JP2012073184 W JP 2012073184W WO 2013039061 A1 WO2013039061 A1 WO 2013039061A1
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B7/00—Control of exposure by setting shutters, diaphragms or filters, separately or conjointly
- G03B7/08—Control effected solely on the basis of the response, to the intensity of the light received by the camera, of a built-in light-sensitive device
- G03B7/091—Digital circuits
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/60—Control of cameras or camera modules
- H04N23/69—Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/71—Circuitry for evaluating the brightness variation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/76—Circuitry for compensating brightness variation in the scene by influencing the image signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/40—Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled
- H04N25/44—Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled by partially reading an SSIS array
- H04N25/443—Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled by partially reading an SSIS array by reading pixels from selected 2D regions of the array, e.g. for windowing or digital zooming
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/40—Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled
- H04N25/46—Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled by combining or binning pixels
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/50—Control of the SSIS exposure
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/71—Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors
- H04N25/75—Circuitry for providing, modifying or processing image signals from the pixel array
Definitions
- the present invention relates to an imaging apparatus, an imaging method, and a recording medium.
- the pixel addition reading method is a method of reading an image signal with a plurality of pixels as one pixel.
- the cutout readout method is a method of reading out an image signal from each pixel.
- the advantage of the pixel addition readout method is that the image signal of an image with a wide angle of view can be read out with low power, the sensitivity is improved because the image signal of a plurality of pixels is added and read out, and the noise component included in the image signal The ratio of is reduced.
- Disadvantages of the pixel addition readout method are that image signals of a plurality of pixels are added, so that the resolution of the image is reduced, and jaggy noise due to a phase shift between pixels appears in the image.
- the advantage of the cutout readout method is that the resolution of the image is high and the occurrence of jaggy noise is small.
- the disadvantages of the cutout readout method are that the angle of view is narrow and the sensitivity is low compared to the pixel addition readout method.
- each reading method has its own advantages and disadvantages. For this reason, a reading method is adopted in which an optimum reading method is selected according to the zoom magnification or the brightness of the subject indicating the brightness of the subject.
- Patent Document 1 discloses an imaging apparatus that switches between a pixel addition readout method and a cutout readout method (non-addition method) according to zoom magnification. This imaging apparatus performs a scaling process and a trimming process in accordance with the image size for display on the read image. In addition, the imaging apparatus can display a high-resolution screen without affecting the display of the electronic viewfinder by switching the readout method.
- Patent Document 2 discloses an imaging apparatus that reads an image signal by switching between a live view readout method (cutout readout method) and a pixel addition readout method for each frame when the brightness of a subject is low.
- This imaging apparatus displays an image on the display unit during a period in which an image signal is read out by a live view readout method, and controls autofocus during a period in which the image signal is read out by a pixel addition readout method.
- Patent Document 3 discloses an imaging apparatus that sets the pixel addition readout method when the shooting location is dark and sets the cutout readout method (decimation readout method) when the shooting location is bright. .
- Patent Documents 1 to 3 may not be able to obtain a good captured image when zooming and imaging a subject.
- the zoom magnification reaches a threshold value due to zooming up and the image signal readout method is switched from the pixel addition readout method to the cutout readout method.
- the subject image becomes dark due to the zoom-up, and the sensitivity of the imaging device is low in the cut-out readout method, so that the proportion of random noise included in the captured image increases. Therefore, it is impossible to obtain a high-quality captured image.
- an imaging apparatus provides: A pixel addition reading method that includes an image sensor in which a plurality of pixels are two-dimensionally arranged and reads image signals of the plurality of pixels of the image sensor as an image signal corresponding to one pixel; An image pickup unit that reads out the image signals of the plurality of pixels in accordance with any one of the read-out reading methods for individually reading out the image signals, and outputs the image signals; A signal processing unit that outputs a captured image defined by the image signal output by the imaging unit; A zoom setting unit that sets the zoom magnification based on a zoom signal that specifies the zoom magnification; A brightness detection unit that detects the brightness of the subject indicating the brightness of the subject; Based on a threshold characteristic whose threshold changes according to the brightness of the subject, a threshold corresponding to the brightness of the subject detected by the brightness detection unit is specified, and the set zoom magnification is compared with the specified threshold; A reading method switching control unit for setting the reading method based on the
- an imaging method provides: It is set to either a pixel addition readout method that reads out image signals of a plurality of pixels of the image sensor as an image signal corresponding to one pixel, or a cutout readout method that individually reads out image signals of all pixels or a part of pixels.
- a high-quality captured image can be obtained according to the brightness and zoom magnification of the subject.
- FIG. 3 is a diagram illustrating a threshold characteristic table of the imaging apparatus according to Embodiment 1.
- FIG. 3 is a flowchart illustrating the contents of an imaging process of the imaging apparatus according to the first embodiment.
- FIG. 10 is a block diagram illustrating a configuration of an imaging apparatus according to another modification of the first embodiment.
- FIG. 6 is a state transition diagram of switching of image signal readout methods of the imaging apparatus according to the second embodiment.
- FIG. 10 is a diagram illustrating a modification of threshold characteristics of the imaging apparatus according to the second embodiment.
- FIG. 10 is a diagram illustrating threshold hysteresis characteristics of a modified example of threshold characteristics of the imaging apparatus according to the second embodiment.
- FIG. 10 is a diagram illustrating a threshold characteristic table of the imaging apparatus according to the third embodiment. It is a block diagram which shows the structural example as a computer of the imaging device which concerns on embodiment.
- the imaging apparatus 100 includes an imaging unit 1, a signal processing unit 2, an operation unit 3, a lightness detection unit 4, a control unit 5, a storage unit 6, and a display unit 7. Yes.
- the imaging unit 1 includes a lens unit and an image sensor unit.
- the lens unit is an optical system having a plurality of lenses, a focus mechanism, an optical zoom mechanism, an iris mechanism, and the like, and forms an image of a subject on a light receiving surface of the image sensor unit.
- the focus mechanism, optical zoom mechanism, iris mechanism, and the like are controlled by the control unit 5.
- the image sensor unit has an imaging device configured by two-dimensionally arranging a plurality of pixels such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor). Each pixel of the image sensor converts an optical signal from a subject incident through the lens unit into an image signal that is an amount of charge. Image signals of pixels arranged in two dimensions constitute a captured image.
- This imaging device has n (for example, 4800) pixels in the horizontal direction (main scanning direction) and m (for example, 3600) pixels in the vertical direction (sub-scanning direction).
- the image sensor unit reads out and outputs an image signal of each pixel according to a reading method (described later) set by the control unit 5.
- the signal processing unit 2 performs A / D conversion processing for converting the image signal output from the imaging unit 1 from analog to digital, signal separation processing for separating the digitized image signal into a luminance signal and a color difference signal, noise removal, Processing such as high image quality processing such as edge enhancement is performed.
- the signal processing unit 2 stores the processed image signal in the storage unit 6 and outputs the image signal as a captured image to the display unit 7.
- the signal processing unit 2 executes electronic zoom processing such as enlargement or reduction of the captured image according to the electronic zoom (digital zoom) magnification notified from the control unit 5.
- the signal processing unit 2 executes scaling processing, trimming, and the like of the captured image to match the number of pixels of the display unit 7 and the number of pixels of the recorded image.
- the operation unit 3 has a plurality of switches such as a zoom operation unit, a power switch, and a shutter switch, and supplies the operation information to the control unit 5 in accordance with a user operation. For example, when the user operates a zoom operation unit configured by a zoom button or the like, the operation unit 3 supplies (outputs) zoom-up or zoom-down operation information as a zoom signal to the control unit 5.
- switches such as a zoom operation unit, a power switch, and a shutter switch
- the brightness detection unit 4 includes an image sensor in which a plurality of image sensors are arranged, detects the brightness of the subject indicating the brightness of the subject, and transmits the detection result to the control unit 5 as the detected brightness.
- the brightness of the subject is an average value of the signal amount of the image signal output from each image sensor of the image sensor when the subject is photographed.
- the control unit 5 includes a processor such as a CPU (Central Processing Unit), a program memory that stores a control program such as a ROM (Read Only Memory) or a flash memory, and a work memory such as a RAM (Random Access Memory).
- the control unit 5 reads the control program stored in the program memory into the work memory and executes it, thereby controlling the imaging unit 1, the signal processing unit 2, the operation unit 3, and the brightness detection unit 4 to perform various processes.
- the control unit 5 controls the storage unit 6 and the display unit 7, stores a processing result in the storage unit 6 as necessary, and displays it on the display unit 7.
- the control unit 5 includes a zoom setting unit 51 and a reading method switching control unit 52 as functional components. These control each part of the imaging device 100 by executing a control program.
- the zoom setting unit 51 sets the zoom magnification with respect to the subject from the wide angle to the telephoto, based on the zoom signal informing the zoom up or zoom down operation information input from the operation unit 3.
- the zoom setting unit 51 sets an optical zoom magnification and an electronic zoom magnification based on the zoom magnification, controls the optical zoom mechanism of the imaging unit 1 according to the optical zoom magnification, and sets the electronic zoom magnification to the signal processing unit 2. Notice.
- the final zoom magnification is a product of the optical zoom magnification and the electronic zoom magnification.
- the readout method switching control unit 52 sets the readout method of the image signal in accordance with the zoom magnification set by the zoom setting unit 51 and the detected brightness (lightness of the subject) detected by the brightness detection unit 4, and the imaging unit 1.
- Image signal readout methods include a pixel addition readout method and a cutout readout method.
- the storage unit 6 is composed of a storage device such as a hard disk or a flash memory, and stores an image signal output from the signal processing unit 2.
- the display unit 7 includes a display screen such as an LCD (Liquid Crystal Display) or an organic EL (Electro Luminescence) display, and displays an image signal output from the signal processing unit 2 as a captured image.
- a display screen such as an LCD (Liquid Crystal Display) or an organic EL (Electro Luminescence) display, and displays an image signal output from the signal processing unit 2 as a captured image.
- the pixel addition reading method is a method of reading an image signal of a plurality of pixels as an image signal of one pixel when an image signal is read from an image pickup device included in the image sensor unit and output. Specifically, in the pixel addition readout method, the image sensor unit performs addition processing or average processing on the image signals of a plurality of pixels, and reads out the image signals as one pixel.
- the pixel addition readout method is usually used on the wide angle side, that is, on the side where the zoom magnification is low. In this readout method, the resolution is reduced to a degree corresponding to the number of pixels to be subjected to addition processing or average processing.
- the ratio of random noise included in the image signal becomes lower than the ratio of random noise included in the image signal by the cut-out readout method.
- the number of pixels of the image sensor is larger than the number of pixels of the display unit 7 or the number of pixels at the time of recording.
- the cutout readout method when an image signal is read out and output from an image sensor included in the image sensor unit, the entire area or a part of the image sensor is cut out, and the image signal of the pixel in the area is converted into an image signal between pixels.
- This is a method of reading out the image signal of the original pixel without performing addition processing or averaging processing.
- the cutout readout method is usually used on the telephoto side, that is, on the side with a high zoom magnification. With this reading method, the resolution does not decrease. However, the proportion of random noise included in the image signal is higher than in the pixel addition readout method.
- the upper part of FIG. 2 shows an example of reading a captured image by the pixel addition reading method.
- the lower part of FIG. 2 shows an example of reading a captured image by the cutout reading method.
- the image sensor 12 is installed in the image sensor 11 of the image sensor unit.
- the imaging device 12 is configured by a total of 64 pixels, that is, eight in the horizontal direction and eight in the vertical direction.
- the image im101 is an image image of a captured image that is generated based on the image signal of 64 pixels that form the image sensor 12.
- the captured image may be a captured image obtained by the imaging element 12 including more than 64 pixels.
- the image sensor unit adds four pixel image signals and reads them as one pixel image signals. Then, the image sensor unit outputs an output image im103 to be displayed among the images im102 generated based on the read image signal. In this example, the image sensor unit outputs an output image im103 corresponding to 16 pixels that is 1 ⁇ 4 of 64 pixels. An image image of the output image im103 is shown in an image im104. In this example, the image im104 corresponds to the entire image image of the image im101. Note that the reason why four pixels to be added in FIG. 2 are selected every other pixel is that each image signal corresponds to one of the RBG color difference signals, and further, is to be added. This is because the image signal corresponds to a color difference signal having the same hue.
- the image sensor unit has the same number of pixels as the image output by the pixel addition readout method among all the pixels of the image sensor 12 to be subjected to image processing.
- a region 12a composed of a total of 16 pixels, 4 in both the horizontal and vertical directions, is cut out.
- the image sensor unit outputs an output image im105 corresponding to the 16 pixels arranged in the cut out region 12a.
- An image image of the output image im105 is shown in an image im106.
- This image im106 is a captured image obtained by the image sensor 12 including 64 pixels.
- an image image displayed in a partial area of the image im101 is displayed in the same area as the area where the image im104 is displayed. Therefore, the image im106 is an image obtained by zooming up the image im104.
- the readout method switching control unit 52 of the control unit 5 sets the pixel addition readout method when the zoom magnification is lower than the threshold for switching the readout method, and reads out when the zoom magnification is higher than the threshold for switching the readout method. Set the law.
- the feature of the imaging apparatus 100 according to the present embodiment is that the threshold value for switching the readout method has a threshold characteristic that varies depending on the brightness of the subject.
- This threshold characteristic is shown as a threshold value ZOOM_TH for switching the readout method shown in FIG.
- the threshold ZOOM_TH has a characteristic of changing to a higher zoom magnification value as the brightness of the subject decreases in the range from the brightness Ba to the brightness Bb of the subject.
- the reason for this threshold characteristic is that when the brightness of the subject decreases, the proportion of random noise included in the image signal increases and the image quality deteriorates. Therefore, as the brightness of the subject decreases, pixel addition reading is performed up to a higher zoom magnification. This is because the image signal is read out by the method. Thereby, when the brightness of the subject is lowered, the deterioration of the image quality of the captured image is suppressed.
- the zoom magnification A (magnification A) is the threshold value ZOOM_TH for switching the readout method as in the conventional case.
- the readout method switching threshold ZOOM_TH is not set. Therefore, the readout method switching control unit 52 sets the readout method to the pixel addition readout method regardless of the zoom magnification.
- the threshold value changes depending on the lightness of the subject.
- the threshold characteristics shown in FIG. 3 are stored in the threshold characteristic table 71 in such a manner that the threshold value of the zoom magnification corresponds to the brightness value of each subject, as shown in FIG. It is stored in the storage unit 6).
- the threshold characteristic is read from the threshold characteristic table 71 by the reading method switching control unit 52 as necessary.
- the threshold characteristic may be stored in a possible form such as a function format instead of the table format.
- FIG. 5 shows an imaging process for capturing a moving image.
- the control unit 5 of the imaging apparatus 100 determines whether an imaging start signal is input from the operation unit 3 (step S1). The imaging start signal is input via the operation unit 3 by the user of the imaging apparatus 100. If the imaging start signal is not input (step S1; NO), the control unit 5 returns to step S1 and waits until the imaging start signal is input.
- step S2 If an imaging start signal is input (step S1; YES), the control unit 5 controls the imaging unit 1 to start imaging (step S2).
- the imaging unit 1 When the imaging is started, the imaging unit 1 generates an image signal for a predetermined time (step S3). And the imaging part 1 reads the produced
- the imaging unit 1 reads an image signal according to a preset reading method. Usually, at the start of imaging, the readout method is set to the pixel addition readout method.
- the brightness detection unit 4 detects the brightness of the subject and transmits it to the control unit 5 as the detected brightness (step S5). Further, the zoom setting unit 51 sets the zoom magnification based on the zoom signal input from the operation unit 3 (step S6).
- the reading method switching control unit 52 acquires a threshold corresponding to the detected lightness received from the lightness detection unit 4 based on the threshold characteristic. Next, the readout method switching control unit 52 sets the readout method according to the magnitude relationship between the acquired threshold and the zoom magnification set by the zoom setting unit 51, and captures information indicating which readout method is set. It transmits to the part 1 (step S7). Note that the magnitude relationship between the threshold acquired by the reading method switching control unit 52 and the zoom magnification set by the zoom setting unit 51 changes not only due to a change in the zoom magnification but also due to a change in the acquired threshold accompanying a change in detected brightness. sell.
- step S8 determines whether or not to stop imaging depending on whether or not an imaging stop signal is input from the operation unit 3 (step S8).
- step S8; NO determines whether or not a power OFF signal is input via the operation unit 3 (step S9). If the power OFF signal is not input (step S9; NO), the control unit 5 returns to step S1 and waits for the input of the imaging start signal. If the power OFF signal is input (step S9; YES), the control unit 5 ends the imaging process.
- the flowchart shown in FIG. 5 shows not only the operation of the imaging apparatus 100 according to FIG. 1 but also the imaging method.
- FIG. 6 shows a configuration of an imaging apparatus 100 according to a modification of the present embodiment.
- the lightness detection unit 4 is a functional component of the signal processing unit 2.
- the signal processing unit 2 has a signal separation processing function for separating an image signal into a luminance signal and a color difference signal.
- the brightness detection unit 4 calculates an average value of the brightness levels of the brightness signal obtained at each pixel at this time, and detects this as brightness. In lightness detection, the average value of the luminance level may be calculated after weighting the pixels in the area determined to be important by the control unit 5.
- the operation of the imaging apparatus 100 in FIG. 6 is the same as the imaging process shown in FIG.
- the imaging apparatus 100 shown in FIGS. 1 and 6 changes the zoom magnification threshold ZOOM_TH related to switching of the image signal readout method in accordance with the brightness of the subject during zooming imaging. Specifically, when the brightness of the subject is low, the imaging apparatus 100 expands the zoom magnification range for imaging by the pixel addition readout method to the telephoto side in accordance with the decrease in the brightness of the subject. Therefore, the switching method of the readout method of the imaging apparatus 100 is caused by image quality deterioration due to random noise and resolution reduction due to pixel addition, as compared with the conventional switching method in which the readout method is switched in a state where the zoom magnification threshold is fixed. An image in consideration of the balance with image quality degradation is obtained, and a high-quality captured image is obtained accordingly. This effect does not matter whether the lightness detection unit 4 is installed as independent hardware or is realized as a functional component of the signal processing unit 2.
- the lightness detection unit 4 is configured by a lightness sensor, for example, in a form independent of the signal processing unit 2, so that the lightness of the subject can be detected with high accuracy.
- the imaging apparatus 100 having the configuration shown in FIG. 6, it is not necessary to install new hardware since the brightness detection unit 4 is included in the functional components of the signal processing unit 2. Therefore, it is possible to contribute to the downsizing of the imaging apparatus 100, and further, it is possible to reduce the manufacturing cost of the imaging apparatus 100.
- the reading method switching control unit 52 sets the reading method. However, the reading method switching control unit 52 may set whether or not the reading method is switched, and may output a switching signal to the image sensor unit of the imaging unit 1 when switching is performed. .
- the reading method switching control unit 52 When the magnitude relationship between the zoom magnification set by the zoom setting unit 51 and the threshold value acquired based on the threshold characteristic and the detected brightness changes, the reading method switching control unit 52 generates a switching signal as switching.
- the zoom magnification has changed during zooming, and as a result, the detected brightness has changed due to the change in brightness of the subject.
- the image sensor unit of the imaging unit 1 uses the first reading method at the time of activation as a reading method set in the image sensor unit in advance, and when a switching signal is input, the previous reading method is changed to another reading method. The image signal is read by switching to.
- the initial readout method at the time of activation is normally set to the pixel addition readout method.
- FIG. 7 shows a configuration of an imaging apparatus 100 according to another modification of the present embodiment.
- the control unit 5 includes a gain setting unit 53. 7 illustrates a case where the lightness detection unit 4 is included in the signal processing unit 2 as a functional component.
- the gain setting unit 53 sets a gain value to be multiplied by the image signal output from the image sensor unit of the imaging unit 1 and transmits the gain value to the imaging unit 1.
- This gain value is set based on the detected lightness (lightness of the subject) input from the lightness detection unit 4 by automatic gain control (Automatic Gain Control) executed in automatic exposure (Automatic Exposure).
- the image sensor unit of the imaging unit 1 multiplies the received gain value by the image signal, and outputs the image signal multiplied by the gain value to the signal processing unit 2 as a new image signal.
- the reason why the image signal is multiplied by the gain value is to amplify the brightness of the subject up to this brightness when the brightness of the subject is lower than the brightness at which the signal processing unit 2 can easily process the image signal. Therefore, the gain value increases when the brightness of the subject is low, and the gain value decreases when the brightness of the subject is high.
- the gain value is set to an upper limit value and a lower limit value of the gain due to circuit restrictions. Therefore, the gain value is fixed to the upper limit value of the gain when the brightness of the subject is lower than the brightness corresponding to the upper limit value of the gain, and is fixed to the upper limit value of the gain when the brightness value is higher than the brightness corresponding to the lower limit value of the gain.
- the image signal output from the imaging unit 1 is multiplied by the gain value. Therefore, when the lightness detection unit 4 is a functional component of the signal processing unit 2, the lightness detection unit 4 divides (normalizes) the average value of the luminance levels included in the image signal input from the imaging unit 1 by the gain value. ) And the brightness obtained by the division is set as the brightness of the subject.
- the gain setting unit 53 divides the lightness that facilitates the processing of the image signal in the signal processing unit 2 by the lightness detected by the lightness detection unit 4, and sets a value obtained as a result as a gain value. That is, the new gain value is obtained as a result of dividing the lightness at which the signal processing unit 2 can easily process the image signal by the lightness detected by the lightness detection unit 4.
- the imaging device 100 having the configuration shown in FIG. 7 includes the lightness detection unit 4 as a functional component of the signal processing unit 2, the imaging device 100 is compact in the same manner as the imaging device 100 having the configuration shown in FIG. In addition, the manufacturing cost of the imaging device 100 can be reduced.
- the reading method switching control unit 52 replaces the threshold characteristic defined as the threshold value depending on the brightness of the subject, and the gain value associated with the brightness of the subject.
- the reading method may be set by using a gain threshold characteristic defined as a threshold value depending on.
- FIG. 8 shows the threshold ZOOM_TH_G as the gain threshold characteristic.
- the threshold value ZOOM_TH_G shown in FIG. 8 is divided by the brightness value of the subject of the threshold value ZOOM_TH in FIG. , And the gain value obtained as a result is obtained.
- G L, Ga, Gb each gain upper limit value of the lower limit of the gain, the gain value corresponding to the brightness Ba, a gain value corresponding to the brightness Bb.
- the gain threshold characteristic is stored in a threshold characteristic table 71 stored in the storage unit 6, for example.
- the reading method switching control unit 52 reads the gain threshold characteristic from the threshold characteristic table 71 and uses it.
- the threshold characteristic table 71 for storing the gain threshold characteristic for example, each value of brightness in FIG. 4 is replaced with a gain value, so that the threshold value is associated with the gain value.
- the reading method switching control unit 52 reads this threshold characteristic from the storage unit 6 in the form of a threshold characteristic table 71, and sets the read threshold characteristic, the zoom magnification set by the zoom setting unit 51, and the gain setting unit 53. The reading method is set based on the gain value to be set.
- step S5 The operation content of the imaging apparatus 100 when the readout method is switched using the gain threshold characteristic is obtained by changing step S5 and step S7 in the imaging process shown in FIG. 5 as follows. It is done.
- step S5 first, the brightness detection unit 4 detects the brightness of the subject.
- the gain setting unit 53 sets a gain value based on the detected brightness.
- step S7 the part “based on the brightness of the subject” is read as “based on the gain value corresponding to the brightness of the subject”.
- the flowchart shown in FIG. 5 shows not only the operation of the imaging apparatus 100 using the gain threshold characteristic but also the imaging method.
- the read method switching control unit 52 may output a read method switching signal instead of the set read method as described above.
- the lightness detection unit 4 is a functional component of the signal processing unit 2 is shown.
- the lightness set independently of the signal processing unit 2 as shown in FIG. 1.
- the detection unit 4 may be used.
- the gain setting unit 53 sets the gain value based on the detected lightness (lightness of the subject) obtained from the lightness detection unit 4.
- the imaging apparatus 100 that uses the gain value for switching the readout method has the same effect as the imaging apparatus 100 that uses the detected brightness for switching the readout method. Can do.
- the imaging device 100 of this embodiment will be described.
- the hardware configuration of the imaging apparatus 100 according to the present embodiment is a function of the readout method switching control unit 52. Is the same except for. Therefore, description of the same part is omitted, and only the reading method switching control unit 52 is described.
- the reading method switching control unit 52 is different from the reading method switching control unit 52 of the first embodiment in that the reading method is set based on a threshold characteristic having a hysteresis characteristic. That is, in the present embodiment, the zoom magnification threshold for switching the reading method depends on the brightness of the subject, and zooming (zooming up) from the wide angle side to the telephoto side, and zooming (zoom) from the telephoto side to the wide angle side.
- the threshold value is set to a different value depending on the case of down.
- the threshold for switching from the pixel addition readout method to the cut-out readout method is as shown in FIG.
- the threshold value A (corresponding to a threshold value ZOOM_UP_TH described later) is set.
- the threshold value for switching from the clipping readout method to the pixel addition readout method is a threshold value A ′ (threshold value ZOOM_DOWN_TH, which will be described later), as shown in FIG. Corresponding).
- the threshold characteristics of the imaging apparatus 100 according to the present embodiment are two types of thresholds.
- the threshold ZOOM_DOWN_TH is set to a value with a smaller zoom magnification than the threshold ZOOM_UP_TH when compared with the same brightness.
- the reading method switching control unit 52 determines which of the two reading methods is the reading method at that time. .
- the read method switching control unit 52 reads the threshold value ZOOM_UP_TH as a threshold value from the storage unit 6 when determined as the pixel addition read method, and reads the threshold value ZOOM_DOWN_TH as a threshold value from the storage unit 6 when determined as the cutout read method.
- the reading method switching control unit 52 acquires a threshold corresponding to the detected brightness from the read threshold ZOOM_UP_TH or ZOOM_DOWN_TH, and determines the magnitude relationship between the zoom magnification set by the zoom setting unit 51 and the acquired threshold. Then, a reading method is set according to the result.
- the reading method switching control unit 52 sets the reading method as follows. First, the reading method switching control unit 52 determines which of the two reading methods is set as the current reading method. As a result of the determination, if the readout method is set to the pixel addition readout method, the readout method switching control unit 52 acquires a threshold value corresponding to the detected brightness from the threshold value ZOOM_UP_TH. Next, when the zoom magnification set by the zoom setting unit 51 is equal to or greater than the threshold value, the readout method switching control unit 52 sets the readout method to the cutout readout method, and if less than the threshold value, adds the readout method to the pixel. Set to readout method.
- the reading method switching control unit 52 acquires a threshold value corresponding to the detected brightness from the threshold value ZOOM_DOWN_TH. Next, if the set zoom magnification is less than or equal to this threshold, the readout method is set to the pixel addition readout method, and if it is greater than this threshold, the cutout readout method is set as the readout method.
- the detected brightness can change depending on the subject as well as the zoom operation. Therefore, even if the zoom magnification does not change due to the zoom operation, the acquired threshold value can also change according to the change of the subject. Therefore, the change in the magnitude relationship between the zoom magnification and the threshold value can be changed by changing the acquired threshold value to a value different from the previous value even when the zoom magnification does not change due to the zoom operation.
- the reason why the threshold value has a hysteresis characteristic is to avoid a situation in which the imaging apparatus 100 takes time to switch the readout method and cannot smoothly read out the image signal and becomes uncontrollable. For example, when moving up and down frequently when zooming up and down in the vicinity of the threshold value, the magnitude relationship between the zoom magnification set by the zoom setting unit 51 and the threshold value frequently changes. Therefore, switching of the reading method can frequently occur. In that case, the imaging apparatus 100 may take time to switch the readout method and may not be able to smoothly read out the image signal.
- the image capturing operation of the image capturing apparatus 100 according to the present embodiment is the same as the content of the image capturing process illustrated in FIG. 5, but partly differs in the process content of step S ⁇ b> 7 related to the reading method switching control unit 52.
- the processing content of step S7 is the same as the content described for the reading method switching control unit 52 according to the present embodiment. Therefore, the flowchart shown in FIG. 5 shows not only the imaging operation of the imaging apparatus 100 but also the imaging method under such a premise.
- the reading method switching control unit 52 may set whether or not the reading method is switched instead of setting the reading method, and may output a switching signal to the image sensor unit of the imaging unit 1 when switching is performed. In this case, when the switching signal is input, the image sensor unit of the imaging unit 1 switches the previous reading method to another reading method and reads the image signal.
- the initial readout method at the time of activation is normally set to the pixel addition readout method.
- FIG. 11 summarizes the conditions under which the readout method of the imaging apparatus 100 according to the present embodiment transitions to another readout method when the readout method switching control unit 52 outputs a switching signal.
- the imaging apparatus 100 starts imaging from the reset state (S101)
- the imaging apparatus 100 transitions to the pixel addition readout method (step S102).
- the condition for transition from the pixel addition readout method (step S102) to the cutout readout method (step S103) is when the zoom magnification becomes equal to or greater than the value corresponding to the detected brightness of the threshold ZOOM_UP_TH (step S104).
- the condition for transition from the cutout readout method (step S103) to the pixel addition readout method (step S102) is when the zoom magnification becomes equal to or smaller than the value corresponding to the detected brightness of the threshold ZOOM_DOWN_TH (step S105).
- the threshold characteristic shown in FIG. 10 may be the threshold characteristic shown in FIG. In FIG. 10, the difference between the threshold characteristics is that the threshold ZOOM_UP_TH and the threshold ZOOM_DOWN_TH converge to one point at the zoom magnification B and the brightness Bb, but in FIG. 12, the threshold ZOOM_DOWN_TH is not always converged to one point. The zoom magnification is smaller than the threshold ZOOM_UP_TH. In the threshold characteristic shown in FIG.
- FIG. 13 shows the hysteresis characteristics of the threshold at each of the brightness Bc, brightness Bd, and brightness Be of FIG. Width between both thresholds according to zoom magnification showing the hysteresis characteristics, w 1 in lightness Bc, w 2 in brightness Bd, it is w 3 in lightness Be.
- the magnitude relationship between w 1 to w 3 is adjusted by adjusting the difference in the gradient of the portion of the threshold ZOOM_UP_TH and the threshold ZOOM_DOWN_TH where the threshold changes to the higher zoom magnification when the brightness decreases.
- the threshold value for switching the readout method for the zoom magnification is changed depending on the brightness of the subject, and the threshold value is provided with a hysteresis characteristic. Even when the zoom-up operation and the zoom-down operation are frequently performed between the wide-angle side and the telephoto side, the imaging apparatus 100 can be prevented from becoming uncontrollable.
- the relationship between the threshold ZOOM_UP_TH and the threshold ZOOM_DOWN_TH is such that the threshold ZOOM_UP_TH is set to a value larger than the threshold ZOOM_DOWN_TH if the brightness of the subject is the same.
- the threshold value ZOOM_UP_TH may be set to a value smaller than the threshold value ZOOM_DOWN_TH. Even in this case, the imaging apparatus 100 can prevent the imaging apparatus 100 from becoming uncontrollable when a zoom-up operation and a zoom-down operation are frequently performed between the wide-angle side and the telephoto side.
- the imaging apparatus 100 shown in FIG. 7 has the characteristic that the threshold value changes according to the change of the gain value as shown in FIG. 8, the imaging device shown in FIG. 1 or FIG. Like 100, it may have hysteresis characteristics. Therefore, the imaging apparatus 100 shown in FIG. 7 has the same effect as the effect described in the present embodiment.
- FIG. 3 An imaging apparatus 100 according to the present embodiment is shown in FIG.
- An imaging apparatus 100 shown in FIG. 14 is obtained by adding a codec unit 8 (including an image compression unit 81 and an image expansion unit 82) and a display control unit 9 to the imaging apparatus 100 shown in FIG.
- the operation unit 3 is provided with an image compression setting switch for designating an image compression rate (referred to as a compression rate) at the time of image compression by the codec unit 8.
- the other hardware configuration is basically the same as the hardware configuration of the first embodiment shown in FIG. In addition, redundant description of the hardware configuration is omitted.
- the imaging apparatus 100 having such a codec unit 8 is employed in, for example, a camera-equipped mobile phone.
- the operation unit 3 inputs the compression rate at the time of image compression designated by the user to the control unit 5 by the operation of the image compression setting switch by the user.
- the image compression unit 81 of the codec unit 8 performs image compression processing on the captured image formed by the image signal that has been subjected to the high image quality processing by the signal processing unit 2 at a compression rate specified by the user, and is generated by image compression processing.
- the compressed image is stored in the storage unit 6.
- the image decompression unit 82 of the codec unit 8 performs image decompression processing on the compressed image read from the storage unit 6.
- the display control unit 9 displays the captured image generated by the image expansion process on the display unit 7.
- the threshold characteristic (hereinafter referred to as compression ratio correspondence threshold characteristic) included in the imaging apparatus 100 according to the present embodiment has a threshold ZOOM_TH as shown in FIG. 3 for each of a plurality of different compression ratios.
- An example is shown in FIG.
- the compression rate correspondence threshold characteristics shown in FIG. 15 are, for example, the threshold characteristics indicated by the threshold ZOOM_THa, the threshold ZOOM_THb, and the threshold ZOOM_THc (represented by ZOOM_THi) for each of the three compression ratios a, b, and c (represented by the compression ratio i).
- the compression rate is higher in the order of compression rates c, b, and a.
- the threshold ZOOM_THi is shifted to a higher zoom magnification as the compression ratio i is higher.
- the reading method switching control unit 52 extracts a threshold value ZOOM_THj corresponding to the compression rate j input from the operation unit 3 from the threshold value ZOOM_THi illustrated in FIG. A specific example will be described.
- the threshold characteristic is associated with a threshold characteristic table 71 in which a plurality of brightness values are associated with each compression rate i, and a threshold value (zoom magnification) is associated with the plurality of brightness values on a one-to-one basis. It is remembered.
- the reading method switching control unit 52 reads the threshold characteristic data from the storage unit 6. Next, the reading method switching control unit 52 extracts a threshold value associated with the lightness equal to the detected lightness from the read threshold value characteristic data.
- the reading method switching control unit 52 extracts two compression ratios i in order from the smallest difference in compression ratio with the compression ratio j. Threshold characteristic data related to one compression rate i is read. Next, the reading method switching control unit 52 extracts the threshold value associated with the lightness equal to the detected lightness from the extracted threshold characteristic data relating to the two compression rates i, and performs interpolation or extrapolation calculation on the compression rate. A threshold value corresponding to the compression rate j is calculated.
- the operation of the imaging apparatus 100 according to the present embodiment is the same as that in the first embodiment except for the processing content in the readout method switching control unit 52, the description thereof is omitted.
- the lightness detection unit 4 may be a functional component of the signal processing unit 2 as shown in FIG. Further, as described in the modification of the first embodiment, the control unit 5 includes the gain setting unit 53 as a functional component, and converts the threshold characteristic by replacing the lightness with the gain value as shown in FIG. (Lightness-gain characteristic) may be used.
- the imaging apparatus 100 has a threshold characteristic in which the threshold value for switching the reading method shifts to the higher zoom magnification as the compression rate increases. That is, as the image compression rate by the image compression process increases, the imaging apparatus 100 reads the image signal to a higher zoom magnification by the pixel addition reading method. Therefore, when the image compression ratio is high, the imaging apparatus 100 reduces the ratio of noise components included in the image signal by reading out the image signal by the pixel addition readout method, and thus can prevent deterioration in the image quality of the compressed image. .
- each of ZOOM_THa, ZOOM_THb, and ZOOM_THc illustrated in FIG. 15 may have a hysteresis characteristic.
- the imaging apparatus 100 can be prevented from becoming uncontrollable even if the zoom-up operation and the zoom-down operation are frequently performed between the wide-angle side and the telephoto side.
- a pixel addition reading method that includes an image sensor in which a plurality of pixels are two-dimensionally arranged and reads image signals of the plurality of pixels of the image sensor as an image signal corresponding to one pixel;
- An image pickup unit that reads out the image signals of the plurality of pixels in accordance with any one of the read-out reading methods for individually reading out the image signals, and outputs the image signals;
- a signal processing unit that outputs a captured image defined by the image signal output by the imaging unit;
- a zoom setting unit that sets the zoom magnification based on a zoom signal that specifies the zoom magnification;
- a brightness detection unit that detects the brightness of the subject indicating the brightness of the subject; Based on a threshold characteristic whose threshold changes according to the brightness of the subject, a threshold corresponding to the brightness of the subject detected by the brightness detection unit is specified, and the set zoom magnification is compared with the specified threshold
- An imaging apparatus comprising:
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Abstract
Description
複数の画素が2次元に配列されている撮像素子を有し、該撮像素子の複数の画素の画像信号を1画素に対応する画像信号として読み出す画素加算読み出し法と、全画素又は一部の画素の画像信号を個別に読み出す切り出し読み出し法のうち、いずれか設定された読み出し方法に従って前記複数の画素の画像信号を読み出し、該画像信号を出力する撮像部と、
前記撮像部が出力した前記画像信号により定義される撮像画像を出力する信号処理部と、
ズーム倍率を指定するズーム信号に基づいてズーム倍率を設定するズーム設定部と、
被写体の明るさを示す被写体の明度を検出する明度検出部と、
前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較した結果に基づいて、前記読み出し方法を設定する読み出し方法切替制御部と、
を備えることを特徴とする。
撮像素子の複数の画素の画像信号を1画素に対応する画像信号として読み出す画素加算読み出し法と、全画素又は一部の画素の画像信号を個別に読み出す切り出し読み出し法のうち、いずれかに設定された読み出し方法に従って前記複数の画素の画像信号を読み出し、該画像信号を出力する撮像ステップと、
前記撮像ステップで出力された前記画像信号により定義される撮像画像を出力する信号処理ステップと、
ズーム倍率を指定するズーム信号に基づいてズーム倍率を設定するズーム設定ステップと、
被写体の明るさを示す被写体の明度を検出する明度検出ステップと、
前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出ステップで検出された被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較した結果に基づいて、前記読み出し方法を設定する読み出し方法切替制御ステップと、
を備えることを特徴とする。
コンピュータに、
撮像素子の複数の画素の画像信号を1画素に対応する画像信号として読み出す画素加算読み出し法と、全画素又は一部の画素の画像信号を個別に読み出す切り出し読み出し法のうち、いずれかに設定された読み出し方法に従って前記複数の画素の画像信号を読み出し、該画像信号を出力する撮像ステップと、
前記撮像ステップで出力された前記画像信号により定義される撮像画像を出力する信号処理ステップと、
ズーム倍率を指定するズーム信号に基づいてズーム倍率を設定するズーム設定ステップと、
被写体の明るさを示す被写体の明度を検出する明度検出ステップと、
前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出ステップで検出された被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較した結果に基づいて、前記読み出し方法を設定する読み出し方法切替制御ステップと、
を実行させるプログラムを格納することを特徴とする。
以下、図面を参照して、本発明の実施形態について詳細に説明する。本実施形態に係る撮像装置100は、図1に示すように、撮像部1、信号処理部2、操作部3、明度検出部4、制御部5、記憶部6、及び表示部7を備えている。
本実施形態の撮像装置100について説明する。本実施形態における撮像装置100のハードウェアの構成は、図1、図6、又は図7に示した実施形態1の撮像装置100のハードウェアの構成と比べると、読み出し方法切替制御部52の機能を除き同一である。よって、同一部分についての説明を省略し、読み出し方法切替制御部52についてのみ説明する。
本実施形態について説明する。本実施形態に係る撮像装置100を、図14に示す。図14に示す撮像装置100は、図1に示す撮像装置100に、コーデック部8(画像圧縮部81、画像伸張部82を含む)、及び表示制御部9を付加したものである。また、操作部3には、コーデック部8による画像圧縮の際の画像圧縮率(圧縮率と呼ぶ)を指定する画像圧縮設定スイッチが設けられている。なお、他のハードウェアの構成は、図1に示した実施形態1のハードウェアの構成と基本的に同じであるので、同一の符号で示す。また、ハードウェアの構成については重複する説明を省略する。このようなコーデック部8を有する撮像装置100は、例えば、カメラ付き携帯電話等に採用されている。
また、上記実施形態において、輝度レベルの平均値を被写体の明度としたが、これに限定されず、光度、照度等に基づいて算出された値を被写体の明度としてもよい。
複数の画素が2次元に配列されている撮像素子を有し、該撮像素子の複数の画素の画像信号を1画素に対応する画像信号として読み出す画素加算読み出し法と、全画素又は一部の画素の画像信号を個別に読み出す切り出し読み出し法のうち、いずれか設定された読み出し方法に従って前記複数の画素の画像信号を読み出し、該画像信号を出力する撮像部と、
前記撮像部が出力した前記画像信号により定義される撮像画像を出力する信号処理部と、
ズーム倍率を指定するズーム信号に基づいてズーム倍率を設定するズーム設定部と、
被写体の明るさを示す被写体の明度を検出する明度検出部と、
前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較した結果に基づいて、前記読み出し方法を設定する読み出し方法切替制御部と、
を備えることを特徴とする撮像装置。
前記閾値特性は、前記被写体の明度の低下に応じて前記閾値が高くなる特性を有し、
前記読み出し方法切替制御部は、前記閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較し、前記設定されたズーム倍率が前記特定された閾値より小さい場合、前記読み出し方法を画素加算読み出し法に設定し、前記設定されたズーム倍率が前記特定された閾値より大きい場合、前記読み出し方法を前記切り出し読み出し法に設定する、
ことを特徴とする付記1に記載の撮像装置。
前記閾値特性は、前記読み出し方法毎に前記被写体の明度に応じて閾値が変化する特性を有し、
前記読み出し方法切替制御部は、現在設定されている読み出し方法に対応する前記閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値との比較結果に基づいて前記読み出し方法を設定する、
ことを特徴とする付記1又は2に記載の撮像装置。
画像圧縮率を示す圧縮率情報に基づいて前記信号処理部が出力した前記撮像画像を圧縮する画像圧縮部を備え、
前記閾値特性は、前記画像圧縮率毎に前記被写体の明度に応じて閾値が変化する特性を有し、
前記読み出し方法切替制御部は、前記画像圧縮率に対応する前記閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する前記閾値を特定し、前記設定されたズーム倍率と前記特定された閾値との比較結果に基づいて前記読み出し方法を設定する、
ことを特徴とする付記1又は2に記載の撮像装置。
前記被写体の明度に応じてゲイン値が変化する明度-ゲイン特性に基づいて、前記明度検出部が検出した被写体の明度に対応するゲイン値を設定するゲイン設定部を備え、
前記撮像部は、前記読み出した画像信号に前記設定したゲイン値を乗じて該画像信号を増幅し、該増幅した画像信号を出力し、
前記閾値特性は、前記明度-ゲイン特性と、前記明度-ゲイン特性に基づいて定まるゲイン値に応じて前記閾値が変化する特性と、を有し、
前記読み出し方法切替制御部は、前記閾値特性に基づいて、前記設定したゲイン値に対応する前記閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較し、前記設定されたズーム倍率が前記特定された閾値より小さい場合、前記読み出し方法を画素加算読み出し法に設定し、前記設定されたズーム倍率が前記特定された閾値より大きい場合、前記読み出し方法を前記切り出し読み出し法に設定する、
ことを特徴とする付記1に記載の撮像装置。
前記明度検出部は、明度センサを備える、
ことを特徴とする付記1乃至5のいずれか1に記載の撮像装置。
前記明度検出部は、前記撮像部が出力する前記複数の画素の画像信号に基づいて前記被写体の明度を求める、
ことを特徴とする付記1乃至5のいずれか1に記載の撮像装置。
読み出し方法切替制御部は、前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較し、該比較により特定されたズーム倍率と閾値との大小関係と、前回行った前記比較により特定されたズーム倍率と閾値との大小関係と、が異なるときには、前記読み出し方法の切り替えを指示する切替信号を出力し、前記読み出し方法を切り替える、
ことを特徴とする付記1に記載の撮像装置。
撮像素子の複数の画素の画像信号を1画素に対応する画像信号として読み出す画素加算読み出し法と、全画素又は一部の画素の画像信号を個別に読み出す切り出し読み出し法のうち、いずれかに設定された読み出し方法に従って前記複数の画素の画像信号を読み出し、該画像信号を出力する撮像ステップと、
前記撮像ステップで出力された前記画像信号により定義される撮像画像を出力する信号処理ステップと、
ズーム倍率を指定するズーム信号に基づいてズーム倍率を設定するズーム設定ステップと、
被写体の明るさを示す被写体の明度を検出する明度検出ステップと、
前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出ステップで検出された被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較した結果に基づいて、前記読み出し方法を設定する読み出し方法切替制御ステップと、
を備えることを特徴とする撮像方法。
コンピュータに、
撮像素子の複数の画素の画像信号を1画素に対応する画像信号として読み出す画素加算読み出し法と、全画素又は一部の画素の画像信号を個別に読み出す切り出し読み出し法のうち、いずれかに設定された読み出し方法に従って前記複数の画素の画像信号を読み出し、該画像信号を出力する撮像ステップと、
前記撮像ステップで出力された前記画像信号により定義される撮像画像を出力する信号処理ステップと、
ズーム倍率を指定するズーム信号に基づいてズーム倍率を設定するズーム設定ステップと、
被写体の明るさを示す被写体の明度を検出する明度検出ステップと、
前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出ステップで検出された被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較した結果に基づいて、前記読み出し方法を設定する読み出し方法切替制御ステップと、
を実行させるプログラムを格納することを特徴とするコンピュータ読み取り可能な記録媒体。
2 信号処理部
3 操作部
4 明度検出部
5 制御部
6 記憶部
7 表示部
8 コーデック部
9 表示制御部
11 イメージセンサ
12 撮像素子
51 ズーム設定部
52 読み出し方法切替制御部
53 ゲイン設定部
71 閾値特性テーブル
81 画像圧縮部
82 画像伸張部
100 撮像装置
Claims (10)
- 複数の画素が2次元に配列されている撮像素子を有し、該撮像素子の複数の画素の画像信号を1画素に対応する画像信号として読み出す画素加算読み出し法と、全画素又は一部の画素の画像信号を個別に読み出す切り出し読み出し法のうち、いずれか設定された読み出し方法に従って前記複数の画素の画像信号を読み出し、該画像信号を出力する撮像部と、
前記撮像部が出力した前記画像信号により定義される撮像画像を出力する信号処理部と、
ズーム倍率を指定するズーム信号に基づいてズーム倍率を設定するズーム設定部と、
被写体の明るさを示す被写体の明度を検出する明度検出部と、
前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較した結果に基づいて、前記読み出し方法を設定する読み出し方法切替制御部と、
を備えることを特徴とする撮像装置。 - 前記閾値特性は、前記被写体の明度の低下に応じて前記閾値が高くなる特性を有し、
前記読み出し方法切替制御部は、前記閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較し、前記設定されたズーム倍率が前記特定された閾値より小さい場合、前記読み出し方法を画素加算読み出し法に設定し、前記設定されたズーム倍率が前記特定された閾値より大きい場合、前記読み出し方法を前記切り出し読み出し法に設定する、
ことを特徴とする請求項1に記載の撮像装置。 - 前記閾値特性は、前記読み出し方法毎に前記被写体の明度に応じて閾値が変化する特性を有し、
前記読み出し方法切替制御部は、現在設定されている読み出し方法に対応する前記閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値との比較結果に基づいて前記読み出し方法を設定する、
ことを特徴とする請求項1又は2に記載の撮像装置。 - 画像圧縮率を示す圧縮率情報に基づいて前記信号処理部が出力した前記撮像画像を圧縮する画像圧縮部を備え、
前記閾値特性は、前記画像圧縮率毎に前記被写体の明度に応じて閾値が変化する特性を有し、
前記読み出し方法切替制御部は、前記画像圧縮率に対応する前記閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する前記閾値を特定し、前記設定されたズーム倍率と前記特定された閾値との比較結果に基づいて前記読み出し方法を設定する、
ことを特徴とする請求項1又は2に記載の撮像装置。 - 前記被写体の明度に応じてゲイン値が変化する明度-ゲイン特性に基づいて、前記明度検出部が検出した被写体の明度に対応するゲイン値を設定するゲイン設定部を備え、
前記撮像部は、前記読み出した画像信号に前記設定したゲイン値を乗じて該画像信号を増幅し、該増幅した画像信号を出力し、
前記閾値特性は、前記明度-ゲイン特性と、前記明度-ゲイン特性に基づいて定まるゲイン値に応じて前記閾値が変化する特性と、を有し、
前記読み出し方法切替制御部は、前記閾値特性に基づいて、前記設定したゲイン値に対応する前記閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較し、前記設定されたズーム倍率が前記特定された閾値より小さい場合、前記読み出し方法を画素加算読み出し法に設定し、前記設定されたズーム倍率が前記特定された閾値より大きい場合、前記読み出し方法を前記切り出し読み出し法に設定する、
ことを特徴とする請求項1に記載の撮像装置。 - 前記明度検出部は、明度センサを備える、
ことを特徴とする請求項1乃至5のいずれか1項に記載の撮像装置。 - 前記明度検出部は、前記撮像部が出力する前記複数の画素の画像信号に基づいて前記被写体の明度を求める、
ことを特徴とする請求項1乃至5のいずれか1項に記載の撮像装置。 - 読み出し方法切替制御部は、前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出部が検出した被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較し、該比較により特定されたズーム倍率と閾値との大小関係と、前回行った前記比較により特定されたズーム倍率と閾値との大小関係と、が異なるときには、前記読み出し方法の切り替えを指示する切替信号を出力し、前記読み出し方法を切り替える、
ことを特徴とする請求項1に記載の撮像装置。 - 撮像素子の複数の画素の画像信号を1画素に対応する画像信号として読み出す画素加算読み出し法と、全画素又は一部の画素の画像信号を個別に読み出す切り出し読み出し法のうち、いずれかに設定された読み出し方法に従って前記複数の画素の画像信号を読み出し、該画像信号を出力する撮像ステップと、
前記撮像ステップで出力された前記画像信号により定義される撮像画像を出力する信号処理ステップと、
ズーム倍率を指定するズーム信号に基づいてズーム倍率を設定するズーム設定ステップと、
被写体の明るさを示す被写体の明度を検出する明度検出ステップと、
前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出ステップで検出された被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較した結果に基づいて、前記読み出し方法を設定する読み出し方法切替制御ステップと、
を備えることを特徴とする撮像方法。 - コンピュータに、
撮像素子の複数の画素の画像信号を1画素に対応する画像信号として読み出す画素加算読み出し法と、全画素又は一部の画素の画像信号を個別に読み出す切り出し読み出し法のうち、いずれかに設定された読み出し方法に従って前記複数の画素の画像信号を読み出し、該画像信号を出力する撮像ステップと、
前記撮像ステップで出力された前記画像信号により定義される撮像画像を出力する信号処理ステップと、
ズーム倍率を指定するズーム信号に基づいてズーム倍率を設定するズーム設定ステップと、
被写体の明るさを示す被写体の明度を検出する明度検出ステップと、
前記被写体の明度に応じて閾値が変化する閾値特性に基づいて、前記明度検出ステップで検出された被写体の明度に対応する閾値を特定し、前記設定されたズーム倍率と前記特定された閾値とを比較した結果に基づいて、前記読み出し方法を設定する読み出し方法切替制御ステップと、
を実行させるプログラムを格納することを特徴とするコンピュータ読み取り可能な記録媒体。
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EP2757769A4 (en) | 2015-05-20 |
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