JP2005252666A - Imaging apparatus and portable telephone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus which generates an alarm when possibility that photographed image blurs is high and which becomes advantageous to cost reduction of product or miniaturization without needing a sensor in detection of blurring. <P>SOLUTION: The imaging apparatus 10 includes an imaging unit 1 for imaging a subject, an image compressing unit 2 for compressing the photographed image, a compression rate calculating unit 3 for calculating a compression rate based on a DCT coefficient value in a block having a relatively high horizontal and vertical frequencies in the DCT coefficient matrix of the n×n pixel block at the stage of the DCT conversion in the image compression, a compression rate comparator 4 for comparing the magnitude of the compression rate of the image before and after the photographing, a blurring detector 5 for judging that the blurring arises by the reduction of the high frequency part of the photographed image when the compression rate is large (the DCT coefficient calculated value is small) to the image to be compared, and a display unit 7 for displaying the alarm, etc. of the blurring. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus having a solid-state imaging device such as a CCD image sensor, and more particularly to an imaging apparatus having a camera shake warning function (camera shake detection function).

  In a conventional imaging device, for example, when the photographer is shooting in an unstable place or unstable posture, or when the subject is moving, or for shooting at low illumination, the shutter of the imaging device In some cases, such as when the speed is slow, the captured image may be deteriorated due to camera shake. In order to prevent the deterioration of the captured image due to such camera shake, an imaging apparatus that warns that the image captured at that time may be deteriorated due to camera shake every time the shutter is released has been proposed. In this case, an imaging apparatus having a sensor such as an angular velocity sensor or an acceleration sensor as a camera shake detection unit has been proposed.

  For example, in Patent Document 1 below, there is a means for displaying information determined by the imaging device before and after photographing together with the reproduced image data when reproducing a captured image or reproducing a stored image file. For example, when playing back images shot with a camera shake warning due to slow shutter speed before shooting, the display means informs the user that the camera shake warning has been issued. The information can be a material for determining the appearance of the image taken by the user, and as a result, the user can take measures such as re-taking.

  In Patent Document 2 below, an imaging apparatus using an acceleration sensor is proposed to detect the presence or absence of vibration including camera shake.

JP 2003-158646 A JP 2001-197351 A

  However, (1) especially when a beginner fully presses the release switch regardless of the camera shake warning, he / she tends to put too much force on the finger pressing the switch rather than half-pressed, resulting in camera shake. is there. In addition, (2) even if the user is given information that the image was taken in a situation in which camera shake has occurred, it is up to the user to determine whether or not the camera is actually shaking. It is entrusted, and it is difficult for all users to make a correct judgment for slight camera shake unless there is much knowledge about images. Furthermore, (3) camera shake warning can be easily predicted when the shutter speed is slow, such as when shooting in a dark place, but the shutter speed does not slow when shooting outdoors during the day in fine weather. Therefore, the camera shake warning due to the shutter speed cannot be issued.

  Further, (4) even if an angular velocity sensor or an acceleration sensor is used as a camera shake detection sensor, the cost naturally increases accordingly. In particular, (5) in a mobile phone with an imaging device, it is required to mount parts with as small a component shape as possible with an emphasis on portability. Therefore, using a sensor that is lightweight and small in size. However, if a part is mounted, the volume of the part increases.

  In recent years, an acceleration sensor of several millimeters square has been developed by using MEMS (Micro-Electronics-Mechanism-System) technology, and such an acceleration sensor can be used as a camera shake detection sensor. Because of the cost, such a sensor can be easily mounted from an expensive digital camera, and it is difficult to adopt such a sensor with an inexpensive digital camera or a mobile phone with an imaging device.

  The present invention has been made in order to solve the various problems as described above, and when there is a high possibility that the captured image is an image captured in a camera shake state, a sensor such as an acceleration sensor is used. The objective is to provide an imaging device that can reliably detect camera shake and issue a warning to the user, and can contribute to cost reduction and downsizing of the product when realizing such functions. Yes.

  An imaging apparatus according to the subject of the present invention includes an imaging unit that images a subject, an image compression unit that compresses and encodes an image captured by the imaging unit, and a compression and encoding that is output from the image compression unit. An image recording unit that records an image, a compression rate calculation unit that calculates a compression rate at a certain stage of a processing system in the image compression unit, a compression rate comparison unit that compares the compression rates of images before and after shooting, And a camera shake detection unit that detects the presence or absence of camera shake based on the comparison result of the compression ratios.

  Hereinafter, various embodiments of the subject of the present invention will be described in detail along with the effects and advantages thereof with reference to the accompanying drawings.

  According to the subject matter of the present invention, it is usually performed whenever an image is compressed and recorded without newly providing a sensor component such as an acceleration sensor (and thus enabling cost reduction and downsizing of the product). It is possible to detect camera shake in the middle of the processing system.

(Embodiment 1)
FIG. 1 is a block diagram showing a basic configuration of an imaging apparatus 10 according to the present embodiment. In the figure, the imaging apparatus 10 includes an imaging unit using a CCD image sensor or the like as a solid-state imaging device for imaging a subject (the unit incorporates an A / D conversion unit for an output signal of the CCD image sensor) 1 And an image compression unit 2 that compresses and encodes a captured image (digital data) output after the A / D conversion by the imaging unit 1, and a recording such as a frame memory that stores the compressed and encoded image And an image recording unit 6 for storing in a medium. Furthermore, the imaging apparatus 10 includes, as circuit components constituting the core of the present invention, a compression rate calculation unit 3 that calculates a compression rate when compressing an image, a compression rate of a pre-shooting image, and a compression rate of a post-image. The compression ratio comparison section 4 for comparing the above, the camera shake detection section 5 for detecting the presence or absence of camera shake based on the comparison result in the compression ratio comparison section 4, and the detection result of the presence or absence of camera shake output from the camera shake detection section 5 will be described later. A display unit (device portion incorporating a monitor and its driver) 7 for displaying a camera shake warning and a message for confirming the necessity of storing the image after that, and a command input for inputting a signal indicating the user's intention to store the imaging data Part 8. As described above, among these components, the core part of the present embodiment is a signal processing unit including the compression rate calculation unit 3, the compression rate comparison unit 4, the camera shake detection unit 5, and the display unit 7. (Processing system). In particular, as will be described later, the compression rate calculation unit 3 is a part that calculates the compression rate at the stage of DCT conversion corresponding to a processing step in the middle of the processing system in the image compression unit 2. M × m (m is an arbitrary integer smaller than n) blocks including the lower rightmost block (n, n) on the diagonal line in the n × n DCT coefficient matrix obtained by DCT conversion for the n pixel block A compression rate indicating the degree of bias of the high frequency component is calculated based on the bias or variation of the DCT coefficient value.

  Next, an image compression method in the image compression unit 2 of FIG. 1 will be described using the block diagram of FIG. Here, a description will be given using a JPEG method using a DCT method that is a lossy compression method. First, after converting the RGB color space to the YUV color space based on the original image 101, the YUV conversion unit 102 performs image processing for each n × n pixel block, for example, for each 8 × 8 pixel block with n = 8. Split. Thereafter, a DCT (Discrete Cosine Transform) unit 103 performs conversion to the spatial frequency domain using DCT, and clarifies the distribution of high-frequency components and low-frequency components for an 8 × 8 pixel image. (Calculation of n × nDCT coefficient matrix). Thereafter, the quantization unit 104 uses the values of the quantization table 107 for 8 × 8 = 64 pixels to divide the DCT coefficient of each pixel by the quantization table value at the corresponding coefficient position, thereby performing quantization. To increase the compression rate by reducing the information held in the image. The compression rate can be freely changed depending on what parameter is set to the table value of the quantization table 107. Generally, the higher the compression rate, the lower the image quality. Thereafter, the entropy encoding unit 105 performs the operation of changing the length of the entropy codeword based on the quantized data to reduce the space capacity in which the encoded data is stored as much as possible, and then compressing the data. An image 106 is generated.

  In general, it can be said that high-frequency components included in an image have a great influence on the compression rate of the image. That is, the “high frequency component” is the contour of the subject, and the sharper the contour, the lower the compression rate. In other words, when the subject is imaged with the same composition, the image when the image is shaken or defocused has a lack of the outline compared to the image when no image blur occurs. As a result, the compression rate becomes high (images taken by camera shake → high frequency components are small → the compression rate is high).

  The present invention uses the above-described logic, and when the same subject is imaged under the same conditions, the compression ratios of the images that are essentially the same are different, resulting in compressed images having different file sizes. If the file size is generated, a file with a small file size is processed at a higher compression ratio than a file with a large file size, that is, the high-frequency component of the outline is missing, causing camera shake. It can be judged as a thing.

  When the compression rate comparison unit 4 in FIG. 1 compares the compression rates, it is a matter of course that an image to be compared is necessary. In this case, the first image to be compared is captured when the release switch of the digital camera or camera-equipped mobile phone equipped with the imaging device 10 is half-pressed, and the image is captured when the release switch is fully pressed. Is a second image, and the compression rate comparison unit 4 compares the compression rates of the first and second images.

  The compression rate calculation unit 3 in FIG. 1 predicts the compression rate of an image based only on the result of the processing stage in the DCT unit 103 in FIG. 2, as will be described later. For this reason, since the image compression operation is not actually accompanied, there is an advantage that no extra memory is required and the calculation time is short.

  FIG. 3 shows a DCT coefficient matrix for 8 × 8 pixels after DCT. The horizontal direction of the matrix indicates the frequency component in the horizontal direction of the image, and the vertical direction indicates the frequency component in the vertical direction. On the paper surface of FIG. 3, the horizontal spatial frequency increases as it goes to the right, and the vertical spatial frequency increases as it goes downward. In a general image, most of the energy is biased toward the low frequency side. Therefore, in the DCT coefficient matrix after DCT, the spectrum is concentrated on the upper left corner (a) on the diagonal line and the vicinity thereof, and on the diagonal line. The DCT coefficient value tends to decrease as it goes to the lower rightmost part (b). Therefore, in the image in which no camera shake occurs, the high-frequency component in the contour portion remains, and therefore there is a DCT coefficient of a block near the lowermost right part (b) in FIG. In contrast, in the image when camera shake occurs at the time of shooting, the high-frequency component in the contour portion is almost eliminated, so that the block near the lowermost right part (b) in FIG. Does not exist. If attention is paid to this point, the operation or processing in the compression ratio calculation unit 3 is that the horizontal and vertical spatial frequencies in the DCT coefficient matrix relating to (n × n) pixel blocks after the DCT processing are relatively low. More precisely, only the DCT coefficient values in the high region are counted (m × m) (m <m) in the horizontal and vertical directions from the same part (b) without fail including the rightmost lowermost part (b) block. n) calculating or extracting DCT coefficient values that are unevenly distributed in the block, and predicting the compression rate of the image as an amount that gives a degree of variation in the DCT coefficient values (degree of deviation in the block). It is none other than. In other words, the compression ratio calculation unit 3 has a DCT coefficient value (frequency component) in a region where the horizontal / vertical spatial frequency is high (a region defined by (m × m) blocks on the lower right (b) side). Depending on the degree of bias, a numerical value indicating the degree or distribution of the bias (for example, a numerical value is obtained by comparing the degree of bias with a reference table value, which is not displayed in%). Accordingly, the compression rate of the image is set. Therefore, the compression ratio calculation unit 3 performs the low compression ratio when the uneven distribution value of the DCT coefficient value of the high frequency component in the (m × m) blocks is large, and conversely when the uneven distribution value of the DCT coefficient is small. Assigns a high compression rate as the compression rate of the DCT image.

  Whether or not camera shake has occurred can be determined by how much outline remains in the image and, therefore, how much high-frequency component remains. Therefore, in the comparison of the DCT coefficients, it is not necessary to look at the DCT coefficients of all the 8 × 8 = 64 blocks, and it is sufficient to look at only the high-frequency part on the lower right (b) side of the DCT coefficient matrix of FIG. is there. Therefore, in this embodiment, as described above, the bias of the DCT coefficient in the (m × m) blocks composed of the rightmost lower part (b) and the blocks in the vicinity thereof is used to predict the compression rate. It is assumed to be seen as an evaluation value. For example, after setting n = 8 and m = 4 as a typical example, the degree of bias of the DCT coefficient values for the lowermost 4 × 4 pixels in the 8 × 8 pixel DCT coefficient matrix is numerically calculated. Thus, camera shake detection is performed.

  FIG. 4 is a rear view of the digital camera including the imaging device 10 according to the present embodiment. The example of FIG. 4 shows the shape of the digital camera, but the shape of the cellular phone provided with the imaging device 10 according to the present embodiment is different from that of FIG. 4 (not shown). However, the release switch 201 and the image display LCD monitor 202 shown in FIG. 4 are common to the digital camera and the camera-equipped mobile phone.

  The release switch 201 has a two-action specification, and the imaging apparatus 10 calculates a compression rate of an image captured instantaneously when the release switch 201 is half-pressed, and the release switch 201 is fully pressed. Even when the image is set, the compression rate is calculated by taking in the image at that moment, and the compression rate of the image when half-pressed is compared with the compression rate of the image when fully pressed.

  The image display LCD monitor 202 displays a mark 203 or the like indicating that processing is in progress on the monitor screen while the imaging apparatus 10 calculates the compression rate when half-pressed. When the image pickup apparatus 10 detects camera shake, the image display LCD monitor 202 displays a message or camera shake warning mark for warning the user that camera shake has occurred, such as “camera shakes”. Display on the screen. Further, the image display LCD monitor 202 warns of a camera shake, and further confirms whether or not the DCT-completed image captured in the fully pressed state is further compressed / encoded and stored in the image recording unit 6. indicate.

  Hereinafter, the operation of the imaging apparatus 10 will be briefly described with reference to the flowchart of FIG. When the release switch 201 is pressed halfway, first, the imaging apparatus 10 calculates a compression rate (A) (steps S1 and S2). Next, it is compared whether or not the release switch 201 is fully pressed. When the half-pressed state is released, the process returns to the start. When the release switch 201 is fully pressed from the half-pressed state, the imaging apparatus 10 compresses at this time. (B) is calculated (steps S3 and S4). Next, the imaging apparatus 10 compares the compression rate (A) with the compression rate (B), and when the compression rate (B) when fully pressed is greater than the compression rate (A) when pressed halfway. (B> A), the camera shake detection unit 5 determines that the image captured when fully pressed is causing camera shake, and outputs a drive signal to notify the display unit 7 accordingly. On the screen of the LCD monitor 202, a camera shake warning mark 203 or a warning message is displayed. On the other hand, the compression rate (B) when fully pressed is almost the same as the compression rate (A) when pressed halfway, or If it is smaller, the camera shake detection unit 5 transmits a command signal instructing the image compression unit 2 to proceed with compression / encoding, and as a result, the image compression unit 2 and the image recording unit 6 The image when fully pressed is compressed and stored as it is (steps S5 and S6).

  As described above, the display unit 7 warns that a camera shake has occurred, and at the same time displays a message saying “Do you want to save it” on the screen of the LCD monitor 202, which may cause a camera shake. Ask the user whether to save the image high. At that time, when the user selects not to save the image and inputs a command to that effect from the command input unit 8, the apparatus 10 stores the image in the memory when the release switch 201 is fully pressed. When the captured image is erased and the process returns to the start, and the user selects to save the image when fully pressed and operates the command input unit 8, the apparatus 10 directly displays the image. Compressed and saved (steps S7 and S8).

  In order to calculate the compression ratio, it is necessary to read out all pixels of a solid-state image sensor such as a CCD. However, since the LCD monitor 202 itself is small, the number of pixels of the solid-state image sensor is high. In some cases, all the pixels of the solid-state image sensor cannot be displayed on the LCD monitor 202. For example, even if a CCD having the number of pixels of VGA (640 × 480) is used as the solid-state imaging device, if the number of pixels that can be displayed by the LCD monitor 202 is only the number of pixels of QVGA (320 × 280), the solid-state imaging device 3/4 of all the pixels included in is unnecessary. Also, simply increasing the clock rate in order to ensure a frame rate that can withstand moving images will increase power consumption and circuit size, so the number of pixels read from the solid-state image sensor without changing the clock rate Therefore, it is required to secure a frame rate necessary for moving image display. Therefore, when displaying a moving image using the LCD monitor 202 as a viewfinder, a solid-state imaging device such as a CCD is driven in the “high-speed readout mode” in advance, or unnecessary pixels are thinned out in signal processing at the subsequent stage of the solid-state imaging device. The thinned image is displayed on the LCD monitor 202. The “high-speed reading mode” here refers to reading out pixels of a solid-state image pickup device such as a CCD by thinning out the pixels at a certain rate, or mixing and reading out the same color pixels among RGB pixels at a certain rate. The mode or the mode that reads out a combination of both.

  That is, not only when the release switch 201 is fully pressed and an image to be compressed and recorded is loaded into the memory in the image recording unit 6, but also when the release switch 201 is pressed halfway to calculate the compression ratio, It is necessary to drive the solid-state imaging device in “all-pixel readout mode”. Therefore, when the release switch 201 is half-pressed and fully pressed, the solid-state image sensor is driven from the “high-speed reading mode” when the LCD monitor 202 is displayed as a viewfinder to the “all-pixel reading mode”. The mode needs to be changed.

  FIG. 6 is a timing chart schematically showing the timing at which the release switch 201 is pressed, the driving mode of the solid-state imaging device at that time, and the display on the LCD monitor 202. In FIG. 6, an LCD monitor display 301 represents a moving image, an LCD monitor display 302 represents a still image, and an LCD monitor display 303 represents a display example when an image is stored. “High-speed readout mode” and “all-pixel readout mode” are switched in synchronization with the vertical synchronization signal VD as shown in FIG. When the subject is being projected on the LCD monitor 202 with the camera powered on, the solid-state imaging device is driven in the “high-speed reading mode”, and a moving image at the time of preview is displayed. At this time, the release switch 201 is not half pressed or fully pressed. Then, when the release switch 201 is half-pressed, the solid-state imaging device shifts from the current “high-speed readout mode” to the “all-pixel readout mode” after waiting for the rising timing of the next vertical synchronization signal (pulse) VD, The calculation of the compression rate described above is executed. The LCD monitor display 302 at this time is an image of the entire frame displayed in the “high-speed reading mode” as a still image 302, and at the same time, the LCD monitor 202 indicates that the compression rate is being calculated. A mark 203 is displayed. When the compression rate calculation process is completed, the solid-state imaging device again shifts to the “high-speed reading mode” after the next rising timing of the vertical synchronization signal VD. The LCD monitor display at this time is a moving image 301. Thereafter, when the release switch 201 is fully pressed, the solid-state imaging device shifts from the “high-speed readout mode” to the “all-pixel readout mode” in synchronization with the rising timing of the next vertical synchronization signal VD. At that time, the LCD monitor displays a message 303 “Do you want to save” when camera shake is detected after the compression ratio calculation and comparison processing described above has been performed, and conversely the camera shake is detected. If there is no such message, the message display 303 “Save image” is displayed as it is, and the image captured when fully pressed is compressed and stored in the recording medium in the image recording unit 6.

(Embodiment 2)
The feature of the present embodiment is that “depending on the time when the release switch of the imaging device is half-pressed, (1) first processing for storing the image in the image recording section regardless of whether or not there is camera shake; (2) A switching unit for switching the second process (the processing system described in the first embodiment) for detecting the presence / absence of camera shake for a camera shake warning by the compression ratio calculating unit, the compression ratio comparing unit, and the camera shake detecting unit. The other points are the same as those of the first embodiment. Therefore, in the description of this embodiment, the block diagrams of FIGS. 1 and 2 used in the description of Embodiment 1 are used. Then, the switching unit as a characteristic component of the present embodiment includes a comparison function unit such as a timer and a switch function unit. For example, the switching unit between the YUV conversion unit 102 and the DCT unit 103 in FIG. Arranged between. Processing operations or functions of the image pickup apparatus including such a switching unit will be described below.

  FIG. 7 is a flowchart for realizing different flows depending on the length of time that the release switch 201 in FIG. 4 is half-pressed. Specifically, in FIG. 7, a process (step S9) for comparing the time when the release switch 201 is half-pressed with a predetermined time t is added to the flowchart of FIG. Yes. In other words, when the time during which the release switch 201 is half-pressed by the user (half-press time) is longer than the predetermined time t (half-press time> predetermined time t), the imaging apparatus directly performs the compression rate ( The process proceeds to step S2 for calculating A), and the same process (second process) as the process described in the first embodiment is continued. On the other hand, when the half-press time is equal to or shorter than the predetermined time t and the release switch 201 is fully pressed as it is, the imaging apparatus performs the compression rate (A) calculation process and the compression rate (A), The image is compressed and stored as it is without performing the comparison process (B) (103 → 104 → 105 → 106) (first process).

  This embodiment is effective when shooting a moving subject that causes the images to be shot to be completely different when half-pressed and fully pressed, or when you want to shoot a subject as soon as possible even if camera shake occurs. It is.

(Modification common to Embodiments 1 and 2)
In the first and second embodiments, a block having a relatively high horizontal / vertical spatial frequency in the n × nDCT coefficient matrix calculated by the DCT unit 103, that is, the block (b) at the lower rightmost position on the diagonal line is always used. The compression rate calculation unit 3 calculates the compression rate based on each DCT coefficient in the included (m × m) blocks (m <n). However, instead of this, the compression rate calculation unit 3 may calculate the compression rate based on the data size of the subsequent stage of the entropy encoding unit 105 in FIG. 2 (such a modification is shown in FIG. 2). , 105 → 3 is indicated by a broken line). Alternatively, the file size is calculated by compressing and saving the image when the release switch 201 is pressed halfway in the buffer memory, and the file size is compared with the file size compressed and stored when the release switch 201 is fully pressed. Thus, camera shake may be determined.

  Further, as described above, if the image when the release switch 201 is pressed halfway is to be executed until compression and storage, if it is determined that the image when the release switch 201 is fully pressed causes camera shake. That is, it is determined that the image when the release switch 201 to be compared with the compression ratio is half-pressed does not cause camera shake, and the image pickup apparatus validates the image when the release switch is half-pressed as a recording medium. It can also be saved. Therefore, there is no need to take a new shot just because it causes camera shake.

  Even when a single-action release switch that can be switched on by simply pressing it is used instead of using a two-action release switch that can be half-pressed and fully pressed, two images of the same subject with the same composition and the same shooting conditions can be used. When capturing an image, it is obvious that camera shake can be detected based on the file size of the precompressed recorded image.

(Appendix)
The embodiments of the present invention have been disclosed and described in detail above. However, the above description exemplifies aspects to which the present invention can be applied, and the present invention is not limited thereto. In other words, various modifications and variations to the described aspects can be considered without departing from the scope of the present invention.

  The technique of the camera shake detection method in the present invention can be applied to an imaging apparatus such as a digital camera, and can also be applied to a mobile terminal (a mobile phone or an information terminal device (eg, PDA)) having a camera function.

It is a block diagram which shows the basic composition of the imaging device which concerns on Embodiment 1 of this invention. It is a block diagram which shows each process part of the image compression part of FIG. FIG. 3 is a schematic diagram illustrating an 8 × 8 DCT coefficient matrix according to the present invention. 1 is a rear view of a digital camera with an LCD monitor according to the present invention. 3 is a flowchart illustrating a camera shake detection procedure according to the first embodiment. 6 is a timing chart conceptually showing an operation state of the imaging apparatus according to a release switch state according to the present invention. 10 is a flowchart illustrating a camera shake detection procedure according to the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image pick-up part, 2 Image compression part, 3 Compression rate calculation part, 4 Compression rate comparison part, 5 Camera shake detection part, 6 Image recording part, 7 Display part, 8 Command input part, 10 Imaging device, 101 Original image, 102 YUV Conversion unit, 103 DCT unit, 104 quantization unit, 105 entropy coding unit, 106 compressed image, 107 quantization table, 201 release switch, 202 LCD monitor, 203 mark indicating compression rate calculation, 301 moving image, 302 still Image, 303 Message image.

Claims (5)

An imaging unit for imaging a subject;
An image compression unit that compresses and encodes an image captured by the imaging unit;
An image recording unit for recording the compressed and encoded image output by the image compression unit;
A compression rate calculation unit that calculates a compression rate at a certain stage of the processing system in the image compression unit;
A compression rate comparison unit that compares the compression rate of each image before and after shooting;
A camera shake detection unit that detects the presence or absence of camera shake based on the comparison result of the compression ratio,
Imaging device. The imaging apparatus according to claim 1,
The compression rate calculation unit is a part that calculates the compression rate in a DCT conversion stage corresponding to a processing stage in the middle of the processing system in the image compression unit,
The compression ratio calculation unit includes m × m (m is an arbitrary value smaller than n) including the rightmost lower block (n, n) in the n × n DCT coefficient matrix obtained by the DCT conversion with respect to the n × n pixel block. Based on the bias of the DCT coefficient value in (integer) blocks, the compression rate is calculated,
The compression rate comparison unit compares the compression rate of each image before and after the shooting output by the compression rate calculation unit,
The camera shake detection unit, when the compression rate of the image after shooting is larger than the compression rate of the image before shooting, determines that the camera shake has occurred at the time of shooting,
Imaging device. The imaging apparatus according to claim 1 or 2,
When the camera shake detection unit detects the camera shake, it further includes a display unit that warns the user that the captured image has shaken and asks the user whether or not to store the captured image in the image recording unit. Features
Imaging device. The imaging apparatus according to any one of claims 1 to 3,
According to the time when the release switch of the imaging apparatus is half-pressed, (1) a first process for storing the image in the image recording unit regardless of the presence or absence of camera shake, (2) the compression rate calculation unit, and the Further comprising a switching unit that switches between a compression rate comparison unit and the camera shake detection unit and a second process for detecting the presence or absence of the camera shake for a camera shake warning.
Imaging device. The image pickup apparatus according to claim 1, comprising the image pickup apparatus according to claim 1.
mobile phone.

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