JP2011015092A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow users to easily check the image quality difference between various recording rates prior to photographing and to set recording rates.SOLUTION: An imaging device includes an imaging means for photographing an object and generating image data for encoding; a quantized image generation means for performing orthogonal transformation and quantization for the encoding image data to generate a quantized image; a local decoded image generation means for performing reverse quantization and reverse orthogonal transformation for the quantized image to generate a local decoded image; a configuration means for configuring parameters to control quantization steps for quantized image generation; and a display means. The configuration means divides an image to be encoded into a plurality of areas, and configures parameters so that quantization steps are different for each area. The display means displays a local decoded image generated from a quantized image that is generated by using the parameters configured for each area.

Description

  The present invention relates to an imaging apparatus.

  2. Description of the Related Art A digital video camera is well known as a camera-integrated moving image recording apparatus that captures a subject and compresses and records a moving image obtained thereby. In general, a digital video camera allows a user to select a recording rate before shooting. By selecting the recording rate, the user can set the compression rate when the moving image is compression-encoded. When a recording rate with a high compression rate is selected, the recorded moving image has low image quality, and when a recording rate with a low compression rate is selected, the recorded moving image has high image quality. If the compression rate is low, a high-quality moving image can be obtained. However, since the amount of data after compression increases, the time that can be recorded is shorter than that of a low-quality moving image.

  Although the recording rate can be selected, there is a problem that the difference in image quality due to the difference in recording rate cannot be determined until the recorded image is reproduced, and the user cannot know in advance at the time of recording. In order to solve this problem, a technique has been proposed in which a compression-coded image is displayed and an image obtained at a selected recording rate is displayed (see Patent Document 1).

JP 2006-311366 A

  However, in the proposed technique, only one compressed image when encoded at the selected recording rate is displayed, so the image quality at the selected recording rate can be confirmed, but the recording rate is changed. It was not possible to confirm the difference in image quality. In other words, in the proposed technique, in order for the user to identify the difference in image quality for each recording rate, it is necessary to repeat the operation of re-selecting a different recording rate and displaying it again, which requires a complicated operation. It was. In addition, since the proposed technology cannot simultaneously output compressed images when encoded at multiple recording rates, comparison display on the same screen cannot be performed, and the user intuitively grasps the difference in image quality depending on the recording rate. It was difficult.

  The present invention has been made in view of such problems, and it is an object of the present invention to enable a user to easily check a difference in image quality at a plurality of recording rates before shooting and to easily set a recording rate. To do.

The imaging device of the present invention that solves the above-described problems is
Imaging means for photographing a subject and generating an image for encoding;
A quantized image generating means for generating a quantized image by performing orthogonal transformation and quantization on the image for encoding;
Local decoded image generation means for generating a local decoded image by performing inverse quantization and inverse orthogonal transformation on the quantized image;
A setting means for setting a parameter for controlling a quantization step when generating the quantized image;
Display means,
The setting means divides the image for encoding into a plurality of regions, sets the parameters so that the quantization step is different for each region,
The display means displays the local decoded image generated from a quantized image generated using a parameter set for each region.

  According to the present invention, in the imaging apparatus, the user can easily confirm the difference in image quality at a plurality of recording rates before shooting, and the recording rate can be easily set.

1 is a block diagram illustrating a configuration example of an imaging device corresponding to an embodiment. 6 is a flowchart of an operation example of the imaging apparatus corresponding to the embodiment. The figure which shows the example of the local decoding image displayed at the time of a recording rate setting. 10 is a flowchart of an operation example of the imaging apparatus corresponding to the second embodiment. FIG. 10 is a diagram illustrating an example of a local decoded image corresponding to the second embodiment. 10 is a flowchart of an operation example of an imaging apparatus corresponding to the third embodiment. FIG. 10 is a diagram illustrating an example of a local decoded image corresponding to the third embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]
FIG. 1 shows an imaging apparatus according to Embodiment 1 of the present invention. 1 captures an input image obtained by photographing a subject with the imaging unit 10 as an H.264 image. This is an apparatus that encodes by an H.264 / AVC (Advanced Video Coding) system and outputs the encoded image to a recording medium 118 or a transmission path.

  In the imaging apparatus 100, the imaging unit 10 captures an object using an imaging element such as a CCD or a CMOS. An image for encoding obtained by imaging is input to the adder 101 in units of macro blocks described later. The control unit 116 is a CPU or the like, and governs the overall operation of the imaging apparatus 100 by executing a control program. The operation unit 115 receives an operation input from the user, and the setting of the imaging apparatus 100 is performed according to the received operation input. The operation unit 115 includes a shooting start button, a recording rate setting mode selection button, a cursor movement button for selecting an area corresponding to a desired shooting mode from the local decoded image displayed on the display unit 114, and the like. For example, the recording rate selected and determined by the user using the operation unit 115 is input to the control unit 116, and the encoding parameter of the code amount control unit 105 is encoded so that the control unit 116 performs encoding at the selected recording rate. (Quantization parameter) is set. In addition, a control signal for determining a signal output from the selection unit 113 according to intra prediction and inter prediction is output.

  An operation at the time of encoding using the imaging apparatus 100 will be described. In the imaging apparatus 100, encoding is performed using data of horizontal 16 pixels and vertical 16 pixels constituting a macroblock (hereinafter referred to as MB) as encoding units. The input MB data is input to the adder 101. Here, H. The H.264 encoding is roughly divided into two encoding schemes. First, intra coding is performed using only image data in the same frame. The second is inter coding that performs coding using correlation with other frames. In the case of intra coding, the adder 101 receives the input MB data and the prediction image generated by the intra prediction unit 112. On the other hand, in the case of inter prediction, a prediction image generated by the motion compensation unit 111 is input. The adder 101 takes the difference between the input MB data and the predicted image and outputs the difference to the orthogonal transform unit 102.

  In the orthogonal transform unit 102, the orthogonally transformed image is input to the quantization unit 103, and a quantized image is generated based on the quantization parameter for controlling the quantization step input from the code amount control unit 105. . The generated quantized image is input to the entropy encoding unit 104 and the inverse quantization unit 106, respectively. The entropy encoding unit 104 performs variable length encoding on the input quantized image and outputs the result to the recording medium 118 or another transmission path. At the same time, the generated code amount is output to the code amount control unit 105. The code amount control unit 105 determines the quantization parameter of the next image based on the input generated code amount, and outputs it to the quantization unit 103. The recording medium 118 is a non-volatile recording medium such as a flash memory (registered trademark), and is detachably attached to the imaging apparatus 100.

  The inverse quantization unit 106 inversely quantizes the quantized image output from the quantization unit 103 to restore image data before quantization (image data after orthogonal transformation), and outputs the restored image data to the inverse orthogonal transformation unit 107. The inverse orthogonal transform unit 107 performs inverse orthogonal transform to restore image data (predicted image) before orthogonal transform. This image data is image data to be a reference image at the time of inter coding, and is called a locally decoded image or a local decoded image. In the present embodiment, local decoding image generation is performed by the inverse quantization unit 106 and the inverse orthogonal transform unit 107. This local decoded image is input to the loop filter 109. The loop filter 109 performs deblocking processing to remove block distortion on the local decoded image, and inputs it to the frame memory 110. However, in the case of intra prediction, it is input to the frame memory 110 without performing the deblocking process.

  The motion compensation unit 111 is used in the case of inter prediction. A motion vector for the reference image is detected using the input image and the reference image read from the frame memory 110. An inter prediction image is generated using the detected motion vector and the reference image, and is output to the selection unit 113. The intra prediction unit 112 performs an intra-frame prediction process using the image data recorded in the frame memory 110, generates an intra prediction image, and outputs the intra prediction image to the selection unit 113. The selection unit 113 selects a predicted image to be output based on a selection signal from the control unit 116. In the case of intra prediction, the intra prediction image generated by the intra prediction unit is output to the adder 101. In the case of inter prediction, the inter prediction image generated by the motion compensation unit 111 is output to the adder 101.

  Next, the operation when setting the recording rate will be described. When the recording rate is set, it means that the user sets the recording rate before imaging. The image capturing apparatus 100 has a recording rate of high image quality mode (recording rate with the lowest compression rate), standard mode (recording rate between the high image quality mode and low image quality mode), and low image quality mode ( The recording rate with the highest compression rate). Here, it is assumed that the resolution of the entire image is full HD (1920 × 1080 pixels).

  When moving to a mode for setting a recording rate using the operation unit 115 (hereinafter referred to as a recording rate setting mode), the imaging apparatus 100 starts an encoding process as described above. At that time, the control unit 116 is set so as not to output the recording medium 118 of the entropy encoding unit 104 or another transmission path. In addition, after detecting the shift to the recording rate setting mode, the area calculation unit 117 is activated. The area calculation unit 117 counts the number of input MBs. Since the number of recording rates is 3, the number of horizontal MBs is 120 MB, and the number of vertical MBs is 68 MB (the size of the image at the time of encoding is 1920 × 1088), the number of MBs input from the start of recording is 39 MB. At that time, the code amount control unit 105 is instructed to perform encoding in the high image quality mode. When the number of MBs is 40 to 79, the code amount control unit 105 is instructed to perform encoding in the standard mode. When the number of MBs is 80 to 119, the code amount control unit 105 is instructed to perform encoding in the low image quality mode. Of course, the number of MBs from 0 to 39 may be the low image quality mode, the image quality from 40 to 79 may be the high image quality mode, and the image quality from 80 to 119 may be the standard mode.

  The area calculation unit 117 counts the number of MBs up to 119, resets the number of counts to 0, and counts from 0 the next MB line that has advanced one step in the vertical scanning direction. That is, the code amount control unit 105 is instructed to encode an image area in which the number of MBs in the horizontal scanning direction is 0 to 39 and the number of MBs in the vertical scanning direction is 0 to 67 in the high image quality mode. Similarly, the code amount control unit 105 is instructed to encode, in the standard mode, an image area in which the number of MBs in the horizontal scanning direction is 40 to 79 and the number of MBs in the vertical scanning direction is 0 to 67. Further, the code amount control unit 105 is instructed to encode an image area having the number of MBs in the horizontal scanning direction from 80 to 119 and the number of MBs in the vertical scanning direction from 0 to 67 in the low image quality mode.

  In response to the instruction from the area calculation unit 117, the code amount control unit 105 reduces the quantization parameter output to the quantization unit 103 (decreases the quantization step) in the high-quality mode region, and the quantization unit 103 Reduce image quality degradation. On the other hand, in the low image quality mode region, the quantization parameter output to the quantization unit 103 is increased (the quantization step is increased) so that the quantization unit 103 can reduce much information. In the standard mode area, a quantization parameter having a value between the high image quality mode and the low image quality mode is output to the quantization unit 103.

  The image data quantized by the quantization unit 103 is input to the inverse quantization unit 106. In the recording rate setting mode, it is not output to the entropy encoding unit 104. The control unit 116 controls the entropy encoding unit 104 so that the quantized image data is not input by switching a switch (not shown). The processing after being input to the inverse quantization unit 106 is the same as that at the time of encoding, and the local decoded image is held in the frame memory 110.

  As described above, in the recording rate setting mode, the encoded image is not recorded on the recording medium 118, and the local decoded image of the frame memory 110 is displayed on the display unit 114.

  FIG. 2 is a diagram for explaining the operation from the power-on to the power-off of the image pickup apparatus. In particular, FIG. 2 is a diagram for explaining in detail the operation in the recording rate setting mode. The operation timing of each block in FIG. I will explain.

  In S201, the control unit 116 determines whether or not to enter the recording rate setting mode. This determination is made by the user based on an operation input from the operation unit 115. If the recording rate setting mode is ON, the process proceeds to S202. If the recording rate setting mode is OFF, the process proceeds to S208. In S202, the control unit 116 activates the area calculation unit 117 in response to the recording rate setting mode being turned on. Further, a switch (not shown) is switched so that the output data of the quantization unit 103 is not input to the entropy encoding unit 104.

  In S203, each block operates to perform an encoding process, and a local decoded image is displayed on the display unit 114. In the encoding process of S203, no data is input to the entropy encoding unit 104. Therefore, nothing is recorded on the recording medium 118 even if encoding is performed. When encoding is started, a local decoded image is held in the frame memory 110, and the display unit 114 displays the local decoding. As described above, the local decoded image is an image having different quantization parameters for each region, and the display image has a different image quality depending on the region. The display unit 114 also displays the local decoded image so as to be selectable for each region having a different quantization parameter.

  In S204, the operation unit 115 accepts selection of an image quality mode from the user. The user selects an image quality mode while viewing local decoded images having different image quality for each region. If the user selects “high image quality mode”, the process proceeds to S205, if “standard mode”, the process proceeds to S206, and if “low image quality mode”, the process proceeds to S207. In S205, the quantization parameter value (QP1) input from the code amount control unit 105 to the quantization unit 103 is set small, and the encoding process is performed in the high image quality mode. Here, the control unit 116 notifies the code amount control unit 105 that the “high image quality mode” has been selected.

  In S206, the quantization parameter value (QP2) input from the code amount control unit 105 to the quantization unit 103 is set to a value corresponding to the standard mode, and the encoding process is performed in the standard mode. Here, the control unit 116 notifies the code amount control unit 105 that “standard mode” has been selected. In S207, the quantization parameter value (QP3) input from the code amount control unit 105 to the quantization unit 103 is set to a large value corresponding to the low image quality mode, and the encoding process is performed in the low image quality mode. Here, the control unit 116 notifies the code amount control unit 105 that the “low image quality mode” has been selected. In the code amount control unit 105, the relationship between the quantization parameters QP1, QP2, and QP3 is QP3> QP2> QP1.

  In step S208, the control unit 116 determines whether an instruction to start shooting is received. When the user operates the shooting start button of the operation unit 115 to give a shooting start instruction (“YES” in S208), the process proceeds to S209. In S209, shooting is started in the image quality mode set in any of S205 to S207, and encoding processing and recording on the recording medium 118 are performed. In the encoding process performed at this time, quantized data is supplied to the entropy encoding unit 104, and the entropy encoding result is also stored in the recording medium 118. Encoding and recording are continued until a photographing end operation is performed in S210.

  If the photographing end is selected in S210, the process proceeds to S211. If the photographing end is not selected, the encoding and recording in S209 are continued. In S211, when the imaging apparatus 100 is powered off, the imaging apparatus 100 is powered off and the process is terminated. If the power cannot be turned off, the process returns to S201.

  Next, an example of a local decoded image displayed on the display unit 114 in S203 will be described with reference to FIG. FIG. 3A illustrates an example of a pre-encoding image (RAW image data) output from the image sensor included in the image capturing apparatus 100. FIG. 3B shows an example of a local decoded image displayed on the display unit 114 in S202.

  In FIG. 3B, an area 301 indicates an image area encoded in the high image quality mode. An area 302 indicates an image area encoded in the standard mode. An area 303 indicates an image area encoded in the low image quality mode. As described above, the image is divided into regions according to the number of image quality modes (recording rates) included in the image capturing apparatus 100, and each region is encoded and displayed with a parameter corresponding to the image quality mode. Can be easily communicated.

  The frame 304 functions as a selection acceptance cursor for accepting selection of the shooting mode from the user. The user can move the frame 304 left and right using the operation unit 115. The frame 304 is displayed so as to overlap the region 301, the region 302, or the region 303. When the operation unit 115 is operated left and right, the frame 304 moves to the left and right. When the user selects an area using the operation unit 115, a shooting mode corresponding to the image area where the frame 304 overlaps is set. For example, in the case of FIG. 3, since the frame 304 overlaps the area 301 of the high image quality rate, the high image quality rate is set. Next, when the user performs a recording start operation by operating the photographing button or the like, encoding and recording are started at the recording rate set above.

  In the above embodiment, the case where the area calculation unit 117 divides the image into three in the horizontal scanning direction has been described. However, the number of area divisions is not limited to three as long as it is two or more. Further, the division does not need to be strictly equal, and it is sufficient if a region having substantially the same area can be secured. The number of divisions only needs to match the number of types of recording rates. Further, the dividing direction is not limited to the horizontal scanning direction, and the dividing direction may be divided in the vertical scanning direction. In this case, the area calculation unit 117 encodes an image area in which the number of MBs in the horizontal scanning direction is 0 to 119 and the number of MBs in the vertical scanning direction is 0 to 22 in the high image quality mode. An instruction is issued to 105. Similarly, the code amount control unit 105 is instructed to encode an image area in which the number of MBs in the horizontal scanning direction is 0 to 119 and the number of MBs in the vertical scanning direction is 23 to 44 in the standard mode. Further, the code amount control unit 105 is instructed to encode an image area in which the number of MBs in the horizontal scanning direction is 0 to 119 and the number of MBs in the vertical scanning direction is 45 to 67 in the low image quality mode.

  As described above, in the present embodiment, in the imaging apparatus 100 capable of moving image shooting in a plurality of shooting modes, a local decoded image for each shooting mode can be included in one image and provided to the user. Therefore, the user can easily determine the difference in recording rate corresponding to the shooting mode while viewing one image, so that the shooting mode can be selected without performing a complicated operation.

[Embodiment 2]
In the present embodiment, the entire local decoded image is once displayed, and thereafter an enlargement operation can be received from the user. When the enlargement operation is accepted, the local decoding image is newly generated by recalculating the area for each photographing mode based on the size and position of the designated area.

  With reference to FIG. 4, the operation of the imaging apparatus 100 according to the second embodiment will be described. FIG. 4 shows processing corresponding to this embodiment added to the flowchart of FIG. In this embodiment, S401 to S403 are executed between S203 and S204.

  In step S <b> 401, the control unit 116 determines whether designation of a predetermined enlargement area has been received from the local decoded image displayed on the display unit 114 by a user operation. If it is accepted (“YES” in S401), the process proceeds to S402, and the area is recalculated. On the other hand, when the enlargement function is not activated (“NO” in S401), the process proceeds to S204.

  In S402, the control unit 116 activates the region calculation unit 117 and recalculates the region. The recalculation of this area is performed based on the size and position of the enlarged area received in S401. For example, as shown in FIG. 5A, it is assumed that an area including 30 MB having 45 to 74 MBs is designated as an enlarged area in the horizontal scanning direction. At this time, 30 MB is divided into three, and 10 MB is assigned to each locally decoded image in each shooting mode. Accordingly, the area calculation unit 117 sets the 0 to 54th input MBs as the “high quality mode”, the 55 to 64 as the “standard mode”, and the 65 to 119 as the “low quality mode” for one horizontal scanning period. " In this way, the area calculation unit 117 recalculates the area so that the local decoded images of each mode are uniformly included in the enlarged area. However, strict equality is not required for the division.

  In S403, the recording rate is controlled in accordance with the area subdivided by recalculation, encoding processing is performed, and the enlarged local decoded image is displayed on the display unit 114. At this time, the area calculation unit 117 issues a recording rate instruction to the code amount control unit 105 based on the area subdivided in S402. For example, in the above example, when the number of MBs input from the start of encoding is 0 to 54, the code amount control unit 105 is instructed to perform encoding in the high image quality mode. When the number of MBs is 55 to 64, the code amount control unit 105 is instructed to perform encoding in the standard mode. When the number of MBs is 65 to 119, the code amount control unit 105 is instructed to perform encoding in the low image quality mode. Thus, the areas encoded in the high image quality mode and the low image quality mode occupy 45% of the left and right of the image, respectively. 10% of the center of the remaining image is encoded in the standard mode. The code amount control unit 105 resets the quantization parameter in accordance with the instruction.

  The display unit 114 displays an image corresponding to the designated area among the newly generated local decoded images as an enlarged local decoded image. The display unit 114 does not read the entire local decoded image from the frame memory 110 but reads only the designated area. The control unit 116 manages the addresses of the local decoded images held in the frame memory 110, and the control unit 116 calculates and reads out the enlarged image reading position. At this time, the ratios at which the high image quality mode, the standard mode, and the low image quality mode are displayed are equal. The display unit 114 displays the read local decoded image in an enlarged manner so that a part of the image to be captured is enlarged and the difference in recording rate can be seen. Thereby, the difference of the recording rate of a more detailed part can be shown to a user.

  FIG. 5 is a diagram illustrating an image displayed on the display unit 114 when the enlargement function is turned on. An image 510 in FIG. 5A shows areas with different recording rates in the image for encoding. Compared with FIG. 3B, it can be seen that in FIG. 5A, the areas to which the recording rate is assigned differ due to the re-division of the areas. The image is composed of 120 MBs in the horizontal scanning direction. The 0th to 54th areas 501 are the high image quality mode, the 55th to 64th areas 502 are the standard mode, and the 65th to 119th areas 503. Are encoded in the low image quality mode. In the enlarged area 504, 45th to 74th MBs are designated.

  An image 520 in FIG. 5B shows an enlarged local decoded image when the enlarged area 504 is enlarged and displayed on the display unit 114. An area 506 is an area encoded in the high image quality mode, an area 507 is an area encoded in the standard mode, and an area 508 is an area encoded in the low image quality mode. A frame 505 is a cursor for selecting a recording rate.

  According to the above embodiment, when it is desired to enlarge and display a part of an image to check the image quality, the local image for each recording rate divided evenly for the area arbitrarily designated by the user is displayed. Can do. Thereby, the difference in recording rate can be determined in more detail and easily, so that the recording rate can be determined without performing a complicated operation. However, the division of the designated area does not have to be strictly equal, and it is sufficient if a region having an almost equal area can be secured.

  In the above description of the second embodiment, the user can arbitrarily designate the enlargement area. However, the enlargement area is fixed to a predetermined area in advance, and only the presence / absence of enlargement may be selected by the user. good. Alternatively, a feature extraction process may be performed from the image, and an area of a predetermined size including the feature area may be designated as the enlarged area. In the feature extraction process, an area having a large color change by color detection or an area having a large number of colors may be used as the feature area. Further, high-pass filter processing may be performed to extract a region containing many wide-area components as a feature amount region.

[Embodiment 3]
In the present embodiment, the presence of a human face in an image is detected, and an enlarged region that includes the face is set based on the position information of the face. After that, based on the size and position of the enlarged area, the area for each photographing mode is recalculated to generate a local decoded image again.

  The imaging apparatus according to the present embodiment is characterized in that the face detection unit 120 indicated by a dotted line in the configuration illustrated in FIG. The face detection unit 120 performs face detection using an image input from the imaging unit 10 or an image encoded in any imaging mode, and outputs position information in the detected face image. The face detection algorithm may use a template, or may be detected by detecting the contours of the face, the corner of the eye, the eyes, the nose and the mouth by edge detection. Since face detection itself can use a known algorithm, detailed description is omitted.

  The face detection unit 120 outputs the detected face position information to the region calculation unit 117. The region calculation unit 117 performs region calculation based on the face position information, counts the number of MBs, and notifies the code amount control unit 105 of regions to be encoded in the high image quality mode, the standard mode, and the low image quality mode. Here, the area is calculated so that the entire face is displayed in the enlarged local decoded image. For example, first, the number of MBs included in the left and right ends of the face is calculated using the face position information input from the face detection unit 120. That is, the number of MBs in the horizontal scanning direction of the face area is counted. The MB number is divided by the recording rate number, and the boundary of the area to be encoded at each recording rate is calculated. When the number of MBs obtained by the calculation is counted and the number of MBs is counted up to the boundary in the same manner as the area calculation unit 117 described above, an instruction is issued to the code amount control unit 105. The control unit 116 calculates an address so that the face is displayed in an enlarged manner, reads a local decoded image from the frame memory, and causes the display unit 114 to display it.

  With reference to FIG. 6, the operation of the imaging apparatus 100 according to the third embodiment will be described. FIG. 6 shows processing corresponding to this embodiment added to the flowchart of FIG. In this embodiment, S601 to S604 are executed between S203 and S204.

  In step S601, the face detection unit 120 detects a face area from the captured image. If a face is detected (“YES” in S601), the process proceeds to S602. In step S602, the face detection unit 120 calculates the face position in the image and generates face position information. The face position information is specified by the MB number in the horizontal scanning direction. For example, when the face is included in the 40th to 87th MBs, the face position information is (40, 87).

  In step S <b> 603, the control unit 116 activates the region calculation unit 117 and recalculates the region. The recalculation of this area is performed based on the face position information generated in S502. For example, as shown in FIG. 7, it is assumed that an area including 48 MB with the number of MBs ranging from 40 to 87 in the horizontal scanning direction is designated as a face area. At this time, 48 MB is equally divided into three, and 16 MB is assigned to each locally decoded image in each shooting mode. Here, the MB size that can be divided into three is described as an example, but the division of the region does not have to be strictly equal, and it is sufficient if a region having substantially the same area can be secured. The area calculation unit 117 sets the 0 to 55th input MBs as the “high quality mode”, the 56 to 71 as the “standard mode”, and the 72 to 119 as the “low quality mode” for one horizontal scanning period. To do. In this way, the area calculation unit 117 recalculates the area so that the local decoded images of each mode are uniformly included in the enlarged area.

  If the face area cannot be divided equally, the area may be expanded.

  In S604, the encoding process is performed by controlling the recording rate according to the recalculated area, and the enlarged local decoded image is displayed on the display unit 114. At this time, the area calculation unit 117 issues a recording rate instruction to the code amount control unit 105 based on the area recalculated in S603. For example, in the above example, when the number of MBs input from the start of encoding is 0 to 55, the code amount control unit 105 is instructed to perform encoding in the high image quality mode. When the number of MBs is 56 to 71, the code amount control unit 105 is instructed to perform encoding in the standard mode. When the number of MBs is 72 to 119, the code amount control unit 105 is instructed to perform encoding in the low image quality mode.

  FIG. 7 is a diagram illustrating a case where the face area is enlarged and displayed on the display unit 114. An image 710 shows areas with different recording rates in the image for encoding. The image is composed of 120 MBs in the horizontal scanning direction. The 0 to 55th area 701 is the high image quality mode, the 56th to 71st area 702 is the standard mode, and the 72th to 119th area 703. Are encoded in the low image quality mode. In the face detection area 704, 40th to 87th MBs are designated.

  An image 720 shows an enlarged local decoded image when the face detection area 704 is enlarged and displayed on the display unit 114. An area 706 is an area encoded in the high image quality mode, an area 707 is an area encoded in the standard mode, and an area 708 is an area encoded in the low image quality mode. A frame 705 is a cursor for selecting a recording rate.

  FIG. 7 shows the case where only one face exists in the image. However, if there are a plurality of faces in the image, one of them is detected based on the size of the face, the degree of focus, and the like. And display. That is, the detected face area is the largest, or the face area having the highest degree of focus is detected. Since the method for determining the degree of focus is well known, it will be omitted individually. Note that the user may select a face to be enlarged. For example, a region in which a face is detected in the photographed image is displayed by surrounding it with a frame, and the user can select one of the frames using the operation unit 115 and specify a face for which enlargement display is desired. If it is desired to perform an enlarged display for another face, the same local selection image may be repeated to display the enlarged local decoded image in the same manner. In addition, the user himself / herself may designate the position of the face in the image using the operation unit 115 without using the face detection unit 120. In that case, the same process as described above may be performed for the area designated by the user.

  According to the present embodiment, it is possible to easily determine in detail the image after encoding of the face area for which it is desired to suppress the difference in the recording rate and the deterioration of the image quality, and the recording rate can be set without performing a complicated operation. .

[Other Embodiments]
In the second embodiment, a case where the user designates an enlarged area and displays an enlarged local decoded image, respectively, and in the third embodiment, a case where an enlarged local decoded image is displayed for the face area detected by the face detection unit 120 is individually described. did. However, the display processing of these enlarged local decoded images may be integrated. That is, when the face detection unit 120 detects a face and detects a face, an enlarged local decoded image including the face detection area is displayed. On the other hand, when a face is not detected, the user can specify an enlarged area and display an enlarged local decoded image. In addition, the user may be able to select whether to perform face detection or the user arbitrarily specifies an enlarged region, and processing may be performed according to the user's selection result. In the integration of the embodiments, instead of the user selecting an enlarged region, an embodiment in which a predetermined region or a feature region determined by feature extraction processing is used as an enlarged region may be integrated.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (10)

Imaging means for photographing a subject and generating an image for encoding;
A quantized image generating means for generating a quantized image by performing orthogonal transformation and quantization on the image for encoding;
Local decoded image generation means for generating a local decoded image by performing inverse quantization and inverse orthogonal transformation on the quantized image;
A setting means for setting a parameter for controlling a quantization step when generating the quantized image;
Display means,
The setting means divides the image for encoding into a plurality of regions, sets the parameters so that the quantization step is different for each region,
The image display apparatus, wherein the display unit displays the local decoded image generated from a quantized image generated using a parameter set for each region. The display means displays the local decoded image so as to be selectable for each different area of the parameter,
The imaging apparatus further includes selection accepting means for accepting selection of any region in the local decoded image from a user,
The setting unit sets the parameter corresponding to the area in which the selection receiving unit has received a selection,
The imaging apparatus according to claim 1, wherein the quantized image generating unit generates the quantized image using the set parameter. Encoding means for entropy encoding the quantized image;
The quantized image generated by the quantized image generating unit using the parameter set corresponding to the region for which the selection has been received is entropy-encoded by the encoding unit, and is attached to or detached from the imaging device. Stored in a recording medium that can be mounted,
The quantized image generated by the quantized image generating unit using different parameters for each region in order to receive the selection of the region by the selection receiving unit is not entropy encoded by the encoding unit, and The imaging apparatus according to claim 2, wherein the imaging apparatus is not stored in the recording medium. It further comprises an operation means for accepting an operation from the user,
The operation means accepts designation of an area to be enlarged in the local decoded image displayed by the display means,
The setting means subdivides the image for encoding into a plurality of regions so that the region designated as the region to be enlarged is divided approximately evenly, and the quantization step is different for each region. Reset the parameter to
The display means enlarges and displays an image of a region designated as the region to be enlarged among the local decoded images generated from the quantized image generated using the parameters reset for each region. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is an image pickup apparatus. It further comprises an operation means for accepting an operation from the user,
The operation means receives an instruction to enlarge and display the local decoded image displayed by the display means;
The setting means subdivides the encoding image into a plurality of regions so that a predetermined region in the local decoded image for enlarged display is divided approximately evenly, and the quantization step includes regions. Reset the parameters to be different for each
The display means enlarges and displays an image of the predetermined region among the local decoded images generated from quantization generated using parameters reset for each region. Item 4. The imaging device according to any one of Items 1 to 3. Further comprising face detection means for detecting the position of a human face included in the encoding image;
When the face detection unit detects the position of the face, the setting unit converts the image for encoding into a plurality of regions so that the region including the face is divided approximately evenly according to the position of the face. And re-set the parameters so that the quantization step is different for each region,
The display means enlarges and displays an image of a region including the face among the local decoded images generated from a quantized image generated using parameters reset for each region. The imaging device according to any one of claims 1 to 5. Further comprising designation means for designating a position of a human face included in the image for encoding,
When the position of the face is specified by the specifying unit, the setting unit sets the image for encoding to a plurality of regions so that a region including the face is divided approximately evenly according to the position of the face. And re-set the parameters so that the quantization step is different for each region,
The display means enlarges and displays an image of a region including the face among the local decoded images generated from a quantized image generated using parameters reset for each region. The imaging device according to any one of claims 1 to 5.   The imaging apparatus according to claim 1, wherein the setting unit divides the image for encoding in a horizontal scanning direction or a vertical scanning direction. Imaging means for photographing a subject and generating an image for encoding;
A quantized image generating means for generating a quantized image by performing orthogonal transformation and quantization on the image for encoding;
Local decoded image generation means for generating a local decoded image by performing inverse quantization and inverse orthogonal transformation on the quantized image;
A setting means for setting a parameter for controlling a quantization step when generating the quantized image;
An image pickup apparatus control method comprising display means,
The setting means dividing the image for encoding into a plurality of regions, and setting the parameters such that the quantization step is different for each region;
And a step of displaying the local decoded image generated from a quantized image generated using a parameter set for each region.   A computer program for causing a computer to function as each unit of the imaging apparatus according to any one of claims 1 to 8.