JP2014033333A - Image pickup device and image compression method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate an image compression package in a short time (suitably in real time) while also restraining an increase in circuit scale.SOLUTION: A JPEG encoder 23a compresses main image data while processing an effective area in a still picture frame and compresses sub-image data while processing a blanking area in a still picture frame. A CPU 15 writes the main image compressed data derived by compressing the main image data into the work area in a DDR main memory 16 after compression. The CPU 15 writes the sub-image compressed data derived by compressing the sub-image data and prescribed header data while processing a blanking area in the still picture frame to generate a compressed package and then stores the generated package in the DDR main memory 16.

Description

  The present invention relates to an imaging apparatus and an image compression method, and more particularly, to an imaging apparatus and an image compression method suitable for acquiring still image data encoded in real time.

When a still image is taken and filed in a digital camera or digital video camera, the image data is saved as an uncompressed file or saved as compressed data in JPEG (Joint Photographic Experts Group) format, etc. It is common. When making these files, normally, in addition to the main image having a resolution equivalent to that of the image sensor, an index sub-image called a thumbnail (horizontal 160 pixels × vertical 120 pixels) is simultaneously packaged in a file. Accordingly, the sub-image can be displayed as an index image having a small image size when the still image is reproduced, and the user can check the still image and efficiently select it. This is defined in EXIF (Exchangeable Image File Format) which is an image file standard for digital cameras.

Normally, when taking a still image, the image data acquired via the image sensor is stored in the main memory, and after correcting the image quality, it is compressed in a format such as JPEG to generate the main image stream. To do. Further, if necessary, the main memory image is converted into a thumbnail size and compressed in a format such as JPEG to generate a thumbnail stream. Then, by packaging these as EXIF, a general JPEG file is generated. In this series of processing (hereinafter referred to as still image encoding processing),
(1) Processing for writing image data to main memory (2) While reading image data from main memory, encoding processing of read image data to JPEG format (3) Stream of encoded data to main memory Since a large number of accesses to the main memory are generated by the process such as the write process, the memory bus band is compressed. For this reason, it is necessary to increase the memory processing clock frequency or widen the bus width. As a result, there are problems such as an increase in cost and an increase in power consumption.

  Accordingly, the inventor of the present application has invented an imaging device capable of encoding still image data in real time and storing it in a main memory in parallel with moving image shooting (Patent Document 1). In the imaging apparatus, still image data is temporarily stored in the line memory instead of the main memory, and the still image data read from the line memory is compressed. Japanese Patent Application Laid-Open No. 2004-228561 also describes a configuration in which a JPEG encoder for a main image and a JPEG encoder for a sub image are provided and a main image and a thumbnail are compressed in parallel. With this configuration, real-time EXIF file generation is realized.

Japanese Patent Application No. 2011-033978

  As described above, the inventor of the present application includes an imaging device that includes a JPEG encoder for a main image and a JPEG encoder for a sub image, and generates an image compression package (for example, an EXIF package) by compressing the main image and the thumbnail in parallel. Invented. In general, a JPEG encoder is configured by hardware (a so-called circuit). For this reason, the above-described imaging apparatus has a problem that the circuit scale is increased by using two encoders.

  That is, the conventional technique has a problem that an increase in circuit scale is suppressed and an image compression package cannot be generated in a short time (preferably in real time).

Therefore, the present invention provides an image sensor (12), a still image frame acquisition unit that acquires a still image frame from the moving image data acquired by the image sensor (12) at an arbitrary timing, and the still image frame acquisition unit. A main image size conversion unit (21a) that converts the size of the still image frame acquired by the above in real time to generate main image data, and converts the size of the still image frame acquired by the still image frame acquisition unit in real time. A sub-image size converter (21b) for generating sub-image data, a first line memory (22a) for storing the main image data, a second line memory (22b) for storing the sub-image data, A still image compression unit (23a) for compressing data stored in the first or second line memory (22a, 22b), and the still image pressure A CPU (15) that generates a compressed package using the compressed data compressed by the unit (23a), and a main memory (16) that functions as a work area for generating the compressed package and stores various data. The still image compression unit (23a) compresses the main image data during effective area processing in the still image frame, and compresses the sub-image data during blanking area processing in the still image frame. The CPU (15) writes compressed main image data obtained by compressing the main image data into the work area during the effective area processing in the still image frame, and performs blanking area processing in the still image frame. In the compressed package, the sub-image compressed data obtained by compressing the sub-image data and predetermined header data are written. It generates and provides an imaging apparatus (1) for storing the main memory (16).
In the imaging apparatus (1), the CPU (15) compresses the header data and the main image data in parallel with the compression process of the previous sub-image data by the still image compression unit (23a). The compressed data may be written in the work area used for generating the compressed package.
In the imaging apparatus (1), the still image compression unit (23a) includes the main image data and a compression ratio calculated from the main image compression data, a quantization table used for compression of the main image, and the work area. The quantization table used for compression of the sub-image data may be adjusted based on the sub-image area size and the data size of the sub-image data.
In the imaging apparatus (1), the CPU (15) writes the compressed sub-image data in a sub-image area in the work area, and when an empty area is generated, invalid data is written in the empty area. You may write.
The imaging apparatus (1) further includes a moving image compression unit (20) that compresses moving image data stored in the main memory (16), and the moving image compression unit (20) includes the main image data and the The moving image compression rate may be estimated based on the compression rate calculated from the main image compression data and the quantization table used for compression of the main image.
In the imaging apparatus (1), the moving image compression unit (20) moves the moving image based on the main image data, a compression ratio calculated from the main image compressed data, and a quantization table used for compression of the main image. You may adjust the quantization table used for compression.
In the imaging apparatus (1), the sub-image area in the work area may be a fixed size.
One aspect of the image compression method according to the present invention is acquired by a still image frame acquisition step of acquiring a still image frame from moving image data acquired by an image sensor at an arbitrary timing, and the still image frame acquisition step. A main image size converting step for generating main image data by converting the size of the still image frame in real time, and sub image data by converting the size of the still image frame acquired in the still image frame acquiring step in real time. A sub image size conversion step to be generated; a still image compression step for compressing the main image data or the sub image data stored in the first or second line memory; and the compressed data compressed in the still image compression step. Using a package step to generate a compressed package, wherein the still image pressure In the step, the main image data is compressed during the effective area processing in the still image frame, and the sub-image data is compressed in the blanking area processing in the still image frame. In the packaging step, the still image The main image compressed data obtained by compressing the main image data is written into the work area in the main memory during the effective area processing in the frame, and the sub image data is compressed during the blanking area processing in the still image frame. The compressed package is generated by writing the compressed sub-image data and predetermined header data.

  According to the present invention, it is possible to provide an imaging device and an imaging method that suppress an increase in circuit scale and generate an image compression package in a short time (preferably in real time).

1 is a block diagram illustrating a configuration of an imaging apparatus according to a first embodiment. FIG. 3 is a diagram illustrating a basic configuration for realizing real-time recording processing of a still image frame according to the first embodiment; 2 is a block diagram illustrating a configuration of a still image real-time processing unit according to the first embodiment; FIG. 2 is a block diagram illustrating a configuration of a still image real-time processing unit according to the first embodiment; FIG. 2 is a block diagram illustrating a configuration of a still image real-time processing unit according to the first embodiment; FIG. It is a figure which shows an example of the quantization table concerning Embodiment 1. FIG. FIG. 3 is a block diagram showing a configuration of a size conversion unit according to the first exemplary embodiment. 4 is a timing chart illustrating the operation of each processing unit in each period (effective period, blanking period) of the imaging apparatus according to the first embodiment. FIG. 3 is a conceptual diagram illustrating a configuration of a work area of a DDR main memory according to the first embodiment. 3 is a timing chart illustrating the operation of each processing unit during a blanking period of the imaging apparatus according to the first embodiment; 3 is a timing chart illustrating the operation of each processing unit during a blanking period of the imaging apparatus according to the first embodiment; It is a figure which shows an example of the quantization table concerning Embodiment 1. FIG. It is a figure which shows an example of the quantization table concerning Embodiment 1. FIG. It is a figure which shows an example of the quantization table concerning Embodiment 1. FIG. FIG. 3 is a conceptual diagram showing a state of a work area of a DDR main memory according to the first embodiment. FIG. 3 is a conceptual diagram showing a state of a work area of a DDR main memory according to the first embodiment. FIG. 3 is a conceptual diagram showing a state of a work area of a DDR main memory according to the first embodiment.

<Embodiment 1>
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an imaging apparatus according to the present embodiment. The image capturing apparatus 1 according to the present embodiment acquires still image frames from moving image data at an arbitrary timing based on a user instruction while acquiring moving image data via an image sensor, and converts the still image frames into real time. The encoding (compression) processing is performed by Here, real-time encoding processing refers to performing still image frame encoding processing, for example, JPEG encoding processing, at the same frame rate as the input frame rate of moving image data (camera image). Further, in the following description, the still image frame is described as being acquired at an arbitrary timing based on the user's instruction, but for example, a “still image frame automatic acquisition mode” is prepared, A specific target may be automatically detected, and a still image frame may be automatically acquired according to the detection result.

  In order to realize the above-described operation, the imaging device 1 includes an imaging unit including a lens 11 and an imaging element 12 that photoelectrically converts incident light incident through the lens and generates image data. Furthermore, the imaging apparatus 1 includes a DDR (Double-Data-Rate) main memory 16, a moving image codec 20, a line memory 22, and a JPEG codec 23. The DDR main memory 16, the moving image codec 20, the line memory 22, and the JPEG codec 23 are connected via the bus 10.

  In the DDR main memory 16, moving image data acquired by the image sensor 12 is written. The moving image codec 20 functions as a moving image compression unit that compresses moving image data written in the DDR main memory 16. The moving image codec 20 also functions as a moving image expansion unit that expands the compressed image data. The moving image data acquired from the image sensor 12 is temporarily written in the DDR main memory 16 and then the moving image codec 20 Encoded.

  On the other hand, for still images, a still image frame acquisition unit (not shown) acquires a still image frame from the moving image data acquired by the image sensor 12 at an arbitrary timing, and the still image frame is stored in the line memory 22. The still image data that is a part of is stored. For example, when all 60 frames of moving image data consisting of 60 frames per second are acquired as still image data, the moving image data from the camera signal processing unit 13 may be stored in the line memory 22 sequentially. A frame acquisition unit is unnecessary. Further, when a still image frame is acquired at an arbitrary timing in accordance with a user instruction, for example, it is obtained from a predetermined number of still image frames from moving image data based on the timing at which the user presses a shutter button (not shown) of the imaging apparatus 1. It can be configured by a switch or the like that performs a switch operation so that still image data can be input to the line memory 22.

  The JPEG codec 23 functions as a still image compression unit that compresses still image data stored in the line memory 22. The JPEG codec 23 also functions as a decompression unit that decompresses compressed still image data. The JPEG codec 23 encodes still image data in real time in parallel with the writing of moving image data being shot to the DDR main memory 16. At this time, the DDR main memory 16 is written with the moving image data and the encoded data encoded in real time by the JPEG codec 23.

  In the imaging device 1 configured as described above, the still image frame acquired from the moving image data is directly written in real time without being written in the DDR main memory 16 and then written in the DDR main memory 16. The DDR main memory 16 is configured such that a still image frame (hereinafter referred to as uncompressed image data is also referred to as raw data) acquired from the captured image is encoded and then written to the DDR main memory 16 without being written. The load on the bus bandwidth of the bus 10 is reduced. This makes it possible to perform high-speed shooting processing of still image data having a multi-pixel image size at a speed of 60 frames per second.

  Hereinafter, the imaging apparatus 1 according to the present embodiment will be described in more detail. The imaging apparatus 1 further includes a camera signal processing unit 13 and a zoom / focus control unit 14 that controls the zoom magnification and focal length of the lens 11 under the control of the camera signal processing unit 13. In addition, a CPU (Central Processing Unit) 15, an SD card (SD Memory Card) 17, and a USB (Universal Serial Bus) 18 that control each block are included. Furthermore, it has a size conversion unit 19, a size conversion unit 21, a video signal processing unit 24, an HDMI (High-Definition Multimedia Interface) 25, an LCD (Liquid Crystal Display) 26, and the like. Each processing unit is connected via a bus 10.

  The camera signal processing unit 13 includes a synchronization signal generation unit, a Y / C processing unit, and the like (not shown). The synchronization signal generation unit generates a horizontal synchronization signal and a vertical synchronization signal corresponding to the horizontal size and vertical size of the generated image data and synchronized with the internal clock. As image data from the imaging unit, image data synchronized with the horizontal synchronization signal and the vertical synchronization signal is input to the camera signal processing unit 13. The Y / C processing unit sequentially Y / C-processes a plurality of image data generated by the imaging unit. Y / C processing is processing for separating and converting image data into luminance data (Y) and color data (C). That is, the camera signal processing unit 13 outputs (moving) image data obtained by performing a series of camera signal processing such as color separation, white balance adjustment, and Y / C processing from the captured data.

  The size conversion unit 19 converts the size of the moving image data output from the camera signal processing unit 13. This moving image data is once written in the DDR main memory 16.

  As described above, the moving image codec 20 encodes the moving image data once written in the DDR main memory 16 in a format conforming to, for example, the H.264 / AVC standard or the MPEG2 standard. At the time of encoding, the moving image codec 20 performs an encoding process with reference to an internally managed quantization table. The encoded data after encoding is written in the DDR main memory 16 and transferred to an external memory such as the SD card 17 as necessary. Further, at the time of reproduction, a decoding process is performed on encoded moving image data read from an external memory such as the SD card 17 and written in the DDR main memory 16, for example.

  The SD card 17 is a large-capacity external storage medium, and moving image data and still image data are written to the SD card 17 and can be displayed on the LCD 26. The image data stored in the SD card 17 is once written in the DDR main memory 16, decoded by the moving image codec 20, output to the LCD 26 via the video signal processing unit 24, or output via the HDMI 25. Can do. In addition, the imaging device 1 is connected to various peripheral devices via the USB 18.

  The video signal processing unit 24 performs a series of video signal processing for converting the decoded image data into output data in a format corresponding to the HDMI 25 or the LCD 26, and displays an image via the LCD 26 or a television monitor via the HDMI 25. The image data is output to an external monitor device or the like.

<Normal shooting route and high-speed shooting route>
By the way, the imaging apparatus 1 according to the present embodiment acquires a still image frame from raw data or decoded moving image data written in the DDR main memory 16, converts the size by the size conversion unit 21, and performs line memory 22. Via the JPEG codec 23 and writing to the DDR main memory 16.

  That is, the DDR main memory 16 decodes moving image data (first moving image data) acquired by the image sensor 12 or encoded moving image data read from an external memory such as the SD card 17 ( 2nd moving image data) is written. In this case, a still image frame is also acquired for the first moving image data and the second moving image data at an arbitrary timing according to a user instruction or the like, and is output to the size conversion unit 21. Then, the image size of the still image frame is converted by the size conversion unit 21, a part of the still image data is sequentially written in the line memory 22, and the still image data written in the line memory 22 by the JPEG codec 23. The encoded data encoded in the DDR main memory 16 is output. In addition, when acquiring a still image frame from raw data or decoded video data (first and second moving image data) written in the DDR main memory 16, not only one frame at a timing specified by the user, A plurality of neighboring frames may be combined by weighted averaging or the like to obtain one still image frame.

  Here, the DDR main memory 16 of the imaging apparatus 1 according to the first embodiment is used when JPEG encoding is performed from the camera signal processing unit 13 without passing through the DDR main memory 16 (hereinafter also referred to as a high-speed shooting route). It is preferable to use the line memory 22 on three sides. When JPEG encoding is performed via the DDR main memory 16 (hereinafter also referred to as “normal route”), two of the three sides of the line memory 22 are used. May be used. The reason why the line memory 22 in the first embodiment has a three-surface configuration will be described below.

  In the case of the normal route, raw data is transferred from the DDR main memory 16. In the case of the normal route, if the internal processing unit (for example, a memory controller (not shown)) performs the processing in consideration of the timing of the encoding processing, there is no problem even with the two-plane configuration. Further, when it is desired to complete the processing within a predetermined synchronization signal, measures such as increasing the priority of the bus band to secure the bus band or increasing the operating frequency of the system may be taken.

One of the bottlenecks at the time of the high-speed shooting route of the imaging apparatus 1 according to the first embodiment depends on the encoding processing capability of the JPEG codec 23. JPEG codec 23 is usually
The magnitude relationship of input data amount> encode data amount is established, but depending on the complexity of the image, the amount of encoded data increases due to the allocation of Huffman codes and the above equation may be reversed. In that case, the read processing of the image data is instantaneously delayed, and the processing may fail if only two surfaces of the line memory 22 are used, and the line memory 22 needs to have a three-surface configuration. In other words, in the JPEG codec 23,
If the state of the input transfer rate <the output data transfer rate is always maintained, the processing with only the two-surface configuration is possible. However, there is a case where the state of input transfer rate> output data transfer rate occurs instantaneously. In this case, if the line memory 22 has a three-surface configuration, even if the read processing of image data is delayed, it is absorbed. can do.

  In the present embodiment, when still images are simultaneously acquired during moving image shooting, the still image data from the camera signal processing unit 13 is directly encoded and written to the DDR main memory 16 through the high-speed shooting route. Thus, the amount of data can be reduced as compared to the case where raw data is written. As a result, the bus bandwidth of the bus 10 of the DDR main memory 16 can be secured, and encoded still image data such as still image frames acquired 60 frames per second can be written to the DDR main memory 16.

  By providing three line memories, some of the line memories function as a buffer that absorbs fluctuations in the processing rate during real-time encoding processing, and encoded data after encoding processing is written to the DDR main memory 16. It can function as a buffer for adjusting the timing.

<Real-time recording processing of still image frames>
As described above, the imaging apparatus 1 according to the present embodiment encodes and records a still image frame in real time at a high speed in parallel with the recording of a moving image (hereinafter, the still image frame is encoded by a high-speed shooting route). This processing is also referred to as real-time recording processing, and each processing unit that executes still image frame encoding processing in real time is collectively referred to as a still image real-time processing unit. Details of the still image frame real-time recording process will be described.

  FIG. 2 is a diagram showing a basic configuration for realizing real-time recording processing of a still image frame. 2 and FIGS. 3 to 5 described later, the same components as those of the imaging device 1 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. In FIGS. 2 to 5, a part of the imaging apparatus is extracted and illustrated in order to explain the real-time recording process of the still image frame. In addition, there may be a plurality of size conversion units 21 and the like arranged for main images and thumbnails. A more detailed configuration will be described later with reference to FIG.

  As shown in FIG. 2, a path (high-speed shooting route R1) for performing a real-time recording process for a still image frame D1 input together with a moving image, and raw data or a decoded moving image written in the DDR main memory 16 A selector 27 is provided for switching a path (normal route) for encoding the still image frame D2 acquired from the data. Strictly speaking, the high-speed shooting route R1 in the drawing shows the flow of data when the effective area of the still image frame D1 is processed (details will be described with reference to FIGS. 3 and 4).

  When the still image frame acquired from the moving image data acquired from the image sensor 12 is encoded in real time in the high-speed shooting route R1, the still image frame D1 is selected via the selector 27, and this is stored in the line memory 22. Input sequentially. The line memory 22 writes data less than one frame of still image data. Details of the line memory 22 will be described later. The JPEG encoder 23a arranged at the subsequent stage of the line memory 22 encodes the still image data output from the line memory 22 into the JPEG format and outputs the encoded image. This encoded data is written into the DDR main memory 16.

  On the other hand, in the case of the normal route, the moving image data of raw data written in the DDR main memory 16 is used. The moving image data is obtained by writing moving image data acquired through, for example, the lens 11 and the image sensor 12 to the DDR main memory 16. Alternatively, encoded moving image data input from an external memory such as the SD card 17 is once written in the DDR main memory 16, decoded by the moving image codec 20 shown in FIG. 1, and written again in the DDR main memory 16. Is. In either case, it is raw data or uncompressed moving image data that has been decoded.

  Also for these moving image data, a still image frame is acquired at an arbitrary timing based on a user instruction and output to the size conversion unit 21. A route that is encoded by the JPEG encoder 23a from the DDR main memory 16 via the size converter 21 and the line memory 22 is a normal route. The encoded still image data encoded by the JPEG encoder 23a is written into the DDR main memory 16.

<Configuration of still image real-time processing unit>
Next, the configuration of the still image real-time processing unit (detailed configuration in FIG. 2) will be described with reference to FIGS. FIG. 3 is a block diagram showing a data flow when processing the effective area of the still image frame. Details of the effective area will be described later. The still image real-time processing unit converts the size of the still image frame acquired from the moving image data input via the camera signal processing unit 13 in real time to generate main image data and sub-image data, respectively. A conversion unit 21a and a sub-image size conversion unit 21b are included.

  Line memories 22a and 22b are provided corresponding to the main image size conversion unit 21a and the sub image size conversion unit 21b, respectively. The operations of the line memories 22a and 22b are the same as those of the line memory 22.

  The still image real-time processing unit has only one JPEG encoder 23a inside, and does not include a plurality of JPEG encoders. As described above, the JPEG encoder 23a corresponds to the above-described JPEG codec 23 and is generally configured by hardware (circuit).

  The still image real-time processing unit further includes a main image control unit 28a and a sub image control unit 28b. The main image control unit 28a controls the main image size conversion unit 21a, the line memory 22a, and the JPEG encoder 23a and exchanges data with these processing units. Similarly, the sub image control unit 28b controls the sub image size conversion unit 21b, the line memory 22b, and the JPEG encoder 23a, and exchanges data with these processing units. For example, the main image control unit 28a and the sub image control unit 28b manage a flag indicating whether or not the JPEG encoder 23a is processing a valid area (described later) of a still image frame. The main image control unit 28a and the sub image control unit 28b can be configured as one processing unit.

  The selector 27 converts the still image frame D1 acquired from the moving image data from the camera signal processing unit 13 into the main image size by the main image size conversion unit 21a, and the still image frame D1 also converts the sub image size. The sub image size converted by the unit 21b, the raw data written in the DDR main memory 16 or the still image frame D2 obtained from the decoded moving image data, or the raw data of the DDR main memory 16 or Either still image data obtained by converting the size of the still image frame D3 acquired from the decoded moving image data by the size conversion unit 21a or the size conversion unit 21b is selected and output to the line memory 22a or the line memory 22b.

  In this configuration, real-time encoding processing of still image data of the main image size is executed by the size conversion unit 21a, the line memory 22a, and the JPEG codec 23a. The still image frame includes an effective area and a blanking area. For example, when the image size of a still image frame is 1920 (pixels) × 1080 (lines), the vertical synchronization signal is set to be high level at 1125 lines. The time for 45 lines of this difference is called a blanking area. The above-described period during processing of the effective area is referred to as an effective period, and the period during processing of the blanking area is referred to as a blanking period.

  In general, the JPEG codec 23a encodes still image data by dividing an effective area in a frame into blocks and performing a quantization process using a quantization table on each block. The encoded data is written into the DDR main memory 16. The JPEG codec 23a allows the CPU 15 to recognize the end of the processing of the effective area when the processing of the effective area is completed. Specifically, the JPEG codec 23a sets that the processing of the effective area has ended by setting a flag in the main image control unit 28a and the sub image control unit 28b, that is, that the blanking area period has started. To do. The CPU 15 refers to the presence / absence of this flag setting as appropriate.

  In parallel with the real-time encoding process of the still image data of the main image size, the processing of the still image data of the sub image size is executed. That is, the size conversion process of the still image data to the sub image size is executed by the size conversion unit 21b and the line memory 22b. This size conversion process is performed during the effective period. Still image data converted to the sub-image size (that is, uncompressed YUV format data) is stored in the DDR main memory 16.

  FIG. 4 shows the configuration of the still image real-time processing unit (the configuration itself is the same as in FIG. 3), and is a block diagram showing the flow of data during the blanking period of still image data. The JPEG encoder 23a reads from the DDR main memory 16 still image data of the sub image size corresponding to the still image data of the main image size encoded immediately before. The JPEG encoder 23a encodes still image data of the sub-image size acquired via the selector 27 and the line memory 22a, and writes the encoded data to the DDR main memory 16 via the bus 10. Note that the JPEG encoder 23a may acquire still image data of the sub-image size via the line memory 22b instead of the line memory 22a.

  Further, the CPU 15 performs an EXIF package generation process during the blanking period. Specifically, the CPU 15 writes the header of the EXIF package in parallel with the encoding of the still image data of the sub image size by the JPEG encoder 23a. Details of the processing in the blanking period will be described with reference to FIG.

<Detailed configuration of still image real-time processing unit>
FIG. 5 is a block diagram showing the still image real-time processing unit shown in FIGS. 3 and 4 in more detail. In this example, the imaging device 1 has two paths for processing still image frames acquired from moving image data output from the camera signal processing unit 13. One is a path related to still image data serving as a main image (hereinafter referred to as path 1), and the other is a path related to still image data serving as a sub image (thumbnail) (hereinafter referred to as path 2).

  The path 1 includes a first input image selection unit 27a, a main image size conversion unit 21a, and a line memory 22a. Still image data from the line memory 22a is input to the JPEG encoder 23a and is encoded in real time. The path 2 includes a second input image selection unit 27b, a sub image size conversion unit 21b, and a line memory 22b.

  The main image size conversion unit 21a includes a size conversion unit 211a and a scaler buffer 212a, and the sub-image size conversion unit 21b includes a size conversion unit 211b and a scaler buffer 212b. The scaler buffers 212a and 212b are line memories. The main image size conversion unit 21a and the size conversion unit 21b basically convert still image data input from the camera signal processing unit 13 into sizes for main images and thumbnails, respectively. Details of the main image size conversion unit 21a and the sub image size conversion unit 21b will be described later.

  The line memory 22a includes a memory controller 221a and a buffer 222a including an SRAM. The line memory 22b includes a memory controller 221b and a buffer 222b. The buffers 222a and 222b are three-surface and two-surface buffers, respectively. Further, for example, a buffer 231 having a two-side structure is also connected to the JPEG encoder 23a.

  The buffers 222a and 222b are, for example, SRAMs, and their functions will be described later. The memory controllers 221a and 221b control data access to the buffers 222a and 222b in order to make the SRAM function as a line memory, for example. In addition, when the main image size converters 21a and 21b and the JPEG core 23a have different clock frequencies, processing for converting the clock frequency can be performed.

  In the main image size conversion unit 21a and the size conversion unit 21b, still image frames acquired from the moving image data from the camera signal processing unit 13 or the moving image data from the DDR main memory 16 are the sizes for the main image and the thumbnail, respectively. Is converted to

The still image frames subjected to the size conversion in the horizontal direction and the vertical direction are respectively stored in the buffers 222a and 222b controlled by the memory controllers 221a and 221b. The buffers 222a and 222b constituting the line memories 22a and 22b are buffers for 8 lines for storing pixels necessary for 8 × 8 DCT,
Y8 line x 3 surfaces + C8 line x 3 surfaces (in the case of format 4: 2: 2)
Y16 line x 3 planes + C8 line x 3 planes (when image format is 4: 2: 0)
It becomes the composition of. The number of faces is for single port. Three planes are used, as will be described later, in the real-time processing of JPEG encoding processing to be described later, to absorb the processing degradation when the processing load temporarily decreases and the processing rate decreases, and to the subsequent DDR main memory This is to absorb the delay when the writing process to 16a is stagnant. Depending on the system configuration, a two-sided configuration is also possible.

  The JPEG encoder 23 a encodes the main image data or the sub image data, and transfers the stream generated by the encoding to the DDR main memory 16. Here, the JPEG encoder 23a has a quantization table for a main image and a quantization table for a sub image, and performs encoding processing with reference to the quantization table according to the JPEG compression method. FIG. 6 is a conceptual diagram illustrating an example of a quantization table.

  The quantization table is a table in which different coefficients are used to divide the image data in order to omit relatively high frequency components of the image data after discrete cosine transform (DCT) in JPEG. That is, for example, when an image block is represented by 8 pixels × 8 pixels, a table in which 8 × 8 coefficients as shown in FIG. 6 are arranged. If you want to reduce the compression effect, set each coefficient in the quantization table to a relatively small value (small divisor). If you want to increase the compression effect, set each coefficient in the quantization table to be relatively large (large divisor). ) Value. Although details will be described later, the JPEG encoder 23a adjusts the value of each coefficient of the sub-image quantization table in accordance with the compression ratio of the main image data.

  The JPEG encoder 23a compresses the main image data during the effective period, and compresses the sub image data during the blanking period. Details will be described with reference to FIG.

  The buffer 231 can have a SRAM two-plane configuration or the like. The capacity varies depending on the system configuration, and it is only necessary to absorb the delay when the writing process for writing the transfer data to the DDR main memory 16a is stagnant.

  The first input image selection unit 27a and the second input image selection unit 27b have a function of a selector 27 that selects input image data from a plurality of routes.

<Processing of size converter>
Next, the size converter 21 will be described in detail. FIG. 7 is a block diagram showing details of the size converter 21. It has a two-channel configuration according to the acquired still image data. Thus, data can be processed even when two lines (progressive ODD (odd number), EVEN (even number)) are input simultaneously. By using two channels simultaneously, the processing clock rate of camera processing can be lowered.

  The input image is limited to a necessary frequency characteristic by a horizontal filter (ch1) 41 and a horizontal filter (ch2). For example, when the sampling frequency is thinned out from horizontal 1024 pixels × vertical 768 lines of fs to 512 pixels × 384 lines, filtering is performed by setting the cutoff frequency of the filter to be fs / 4. Then, the pixel is thinned to 512 pixels by the horizontal thinning circuit 43 and written to the scaler buffer 212a. When thinning is performed without limiting the frequency characteristics by the horizontal filter circuits 41 and 42, so-called moire (folding distortion) occurs.

  The scaler processing line memory controller 44 adjusts the scale of the image data thinned out by the horizontal thinning circuit 43. Specifically, with respect to the data after thinning, when the sample point is between the sampling points, a value is obtained by calculating according to the distance of the sample after interpolation from two samples of the filtered image signal, and a straight line between the pixels Perform interpolation etc.

  The still image frame after horizontal interpolation is output to the vertical filter circuits 45 and 46. In order to suppress the occurrence of aliasing distortion as in the horizontal direction, the vertical filter circuits 45 and 46 filter the still image data read from the line memory (scaler buffer 212a) in the vertical direction. After filtering, vertical thinning is performed by the vertical thinning circuit 47, and only necessary image data is written into the line memories 222a and 222b via the memory controllers 221a and 221b at the subsequent stages.

Here, the size conversion can be independently performed in parallel on the main image and the thumbnail image. It is also possible to reduce the buffer size by sharing the scaler buffer 212a. For example, consider a case where the main image still image data is set to fs / 4 by frequency characteristic reduction processing in the horizontal filter circuits 41 and 42. In the filter processing in the thumbnail horizontal filter circuits 48 and 49 connected in series in the subsequent stage, the horizontal 160 pixels × vertical 120 lines are used. Therefore,
Size converter 211a only (each independently used): fs / 12.8 processing required Size converter 211a + 211b
Scaler 1 + Scaler 2 (connected in series in the subsequent stage): fs / 6.4 treatment (because fs / 2 → fs / 4 in the previous stage)
The frequency characteristic limit width can be reduced by connecting to the subsequent stage in series. When the limit width is small, the band order efficiency is good and the image quality is merited if the order is the same. On the other hand, if the image quality is comparable, the order can be reduced. As a result, the necessary line memory of the scaler buffer 212b is reduced, and the surplus line memory can be allocated to other resources.

  The thumbnail size converter uses signals between the vertical filter circuits 45 and 46 and the vertical thinning circuit 47. That is, the size conversion of the still image data after the size conversion by the size conversion unit for the main image is performed. The thumbnail size converter also has horizontal filter circuits 48 and 49, a horizontal thinning circuit, a scaler processing line memory controller, a vertical filter circuit, and a vertical thinning circuit, and outputs a still image image whose size has been converted by the same processing. To do.

  The still image data written in the buffers 222a and 222b is transferred to the DDR main memory 16 every time it is written as, for example, 8-line data. The processing on the DDR main memory 16 side varies depending on the system, but it is normal to write a still image route, a moving image route, calculation results for other camera control signals, and the like into the DDR main memory 16. Therefore, a band capable of processing a rate higher than the data rate of the real-time recording process of the still image frame is secured. However, there may be a moment when the bus bandwidth of the bus 10 is occupied by data other than the real-time recording process of the still image frame. Therefore, the imaging apparatus includes the scaler buffers 212a and 212b, the buffers 222a and 222b, the stream buffer 231 and the like in order to absorb the processing delay of the DDR main memory 16.

<Operation of each processing unit in each period (effective period, blanking period)>
Next, operation details in each period (effective period, blanking period) will be described. FIG. 8 is a timing chart showing the operation of each processing unit in each period (effective period, blanking period). A synchronization signal generation unit in the camera signal processing unit 13 supplies a vertical synchronization signal to each processing unit. The image sensor 12 starts processing the effective area of the still image frame at the timing (t11) when the vertical synchronization signal falls (S1).

  Real-time encoding processing of still image data of the main image size is executed by the JPEG encoder 23a from t11 ′, which is the timing after a predetermined line (eight lines in the above example) of the effective area is stored in the line memory 22 (S2). ). Encoding is performed in units of blocks, and the encoded compressed data is written to the DDR main memory 16 as needed. Since the processing by the JPEG encoder 23a and the like is performed after the minimum processing unit line data is stored in the line memory 22, the falling edge of the vertical synchronization signal, the image sensor output start timing (t11), and the start timing of each processing ( There is a slight deviation from t11 ′) as shown in the figure. The difference between the timings t12 and t12 ′ and the difference between the timings t13 and t13 ′ occur for the same reason. As shown in FIG. 8, there is a difference between the strict blanking period (t12 to t13) and the period (t12 ′ to t13 ′) in which the JPEG encoder 23a and the CPU 15 perform processing, but it can be ignored in general processing. In this specification, the terms “effective period” and “blanking period” are used as a concept of time including this deviation.

  Further, the size conversion of the still image data to the sub image size is performed by the sub image size conversion unit 21b and the line memory 22b from timing t11 ′ (S3). Still image data (YUV format) to the sub-image size after size conversion is stored in the DDR main memory 16 (S3).

  The CPU 15 starts generating a predetermined header of EXIF from timing t11 ′ (S4). Further, the CPU 15 appropriately writes the main image stream encoded by the JPEG encoder 23a in a work area (described later) in the DDR main memory 16 (S4). Further, the CPU 15 may transfer the EXIF package generated before the timing t11 ′ to an arbitrary storage medium (for example, a USB memory or SD card 17 that can be attached to and detached from the imaging device 1) (S5).

  The JPEG encoder 23a sets a flag in the main image control unit 28a and the sub image control unit 28b when the encoding process of the effective area of the still image data is completed (timing t12 ′). The image sensor 12 captures and outputs blanking area data from timing t12 (S6). The sub-image control unit 28b controls the selector 27 so that the still image data of the sub-image size that has been subjected to size conversion from the timing t12 ′ is read from the DDR main memory 16 and supplied to the JPEG encoder 23a. The sub-image size still image data acquired by the selector 27 is supplied to the JPEG encoder 23a. The JPEG encoder 23a encodes the still image data of the sub image size and writes it in the DDR main memory 16 (S7).

  The CPU 15 writes the EXIF header and / or the sub-image stream during the blanking period (timing t12 ′) to generate an EXIF package (S8). Details of this processing will be described with reference to FIGS. After the blanking period ends (timing t13 ′), each processing unit performs the processes described in S1 to S5 again for other still image data.

<Work area configuration>
Prior to the description of the blanking period processing (processing at timings t12 ′ to t13 ′ in FIG. 8), a work area used by the CPU 15 to create an EXIF package will be described. FIG. 9 is a conceptual diagram showing a schematic configuration of the working area. The work area is an area in the DDR main memory 16.

  The work area has a header area, a thumbnail area, and a main image area. The header area is an area having a fixed length from a specified address (hereinafter referred to as address A). The thumbnail area is an area having a fixed size from the end address of the header area (hereinafter referred to as address B). The main image area is a variable-length area having the head address as the end address of the thumbnail area (hereinafter referred to as address C). The CPU 15 writes each data in the work area, and generates an EXIF package by packaging after all the areas have been written. The CPU 15 stores the generated EXIF package in the DDR main memory 16.

<Blanking period processing>
Next, processing of the JPEG encoder 23a and the CPU 15 during the blanking period will be described with reference to FIG. FIG. 10 is a timing chart showing the processes of the JPEG encoder 23a and the CPU 15 during the blanking period, and corresponds to the processes at timings t12 ′ to t13 ′ of FIG.

  FIG. 10A is a timing chart showing a first method of blanking period processing. At the start of the blanking period (timing t12 ′), the JPEG encoder 23a starts encoding still image data of the sub image size (S7). The CPU 15 writes an encoded stream as needed from the start address (address C) of the main image area of the work area during the effective period. Then, the CPU 15 writes the header of the EXIF package from the head address (address A) of the header area at the start of the blanking period (timing t12) (S81). Further, the CPU 15 sequentially writes the stream of sub-image data stored in the DDR main memory 16 after the encoding is completed from the address B of the work area (S81).

  The JPEG encoder 23a finishes encoding the still image data of the sub image size at timing t121. At timing t122 slightly delayed from the end of encoding, the CPU 15 finishes writing the header and sub-image data stream to the work area. Thus, at timing t122, data is written in each area in the work area. The CPU 15 starts a process of packaging work area data into a file from timing t122 (S82). The CPU 15 stores the generated EXIF package in the DDR main memory 16.

  FIG. 10B is a timing chart illustrating a second method of blanking period processing. A difference between the processing method illustrated in FIG. 10B and the processing method illustrated in FIG. 10A will be described. In the case of the processing method of FIG. 10B, the CPU 15 does not perform processing until encoding is completed. Then, the CPU 15 starts writing the header and sub-image data stream to the work area from the timing t124 when the encoding is completed (S81). The CPU 15 starts the packaging process (S82) from the timing t125 when the writing to the work area is completed.

  The processing method shown in FIG. 10A is compared with the processing method shown in FIG. 10B. In the processing method shown in FIG. 10A, the encoding process and the writing process to the work area are performed in parallel. As a result, the start and end timing of the packaging process can be accelerated compared to the processing method shown in FIG. 10B. As a result, the process can be completed more reliably until the end of the blanking period.

<Adjustment of quantization table in JPEG encoder 23a>
As described above, the JPEG encoder 23a compresses still image data of the main image size during the effective period, and compresses still image data of the sub image size during the blanking period. That is, the JPEG encoder 23a performs compression in the order of the main image and the sub-image in accordance with certain still image data. Here, the sub image size still image data is data in which only the size of the main image size still image data is changed. Therefore, there is a correlation between both data.

  Here, the thumbnail area in the work area has a fixed length as shown in FIG. If the compressed data after encoding the still image data of the sub-image size exceeds the size of the thumbnail area, the encoding process needs to be performed again, and the packaging process may not be completed within the blanking period. Therefore, the JPEG encoder 23a pays attention to the above-described correlation, and adjusts the quantization table used for compressing the still image data of the sub-image size so that the compressed data size does not exceed the thumbnail area. Details will be described below with reference to FIG. In the following example, the quantization table for the main image and the quantization table for the sub-image are the same for convenience of explanation.

  FIG. 11A is an example of the quantization table used in the effective period. As described above, each coefficient is set according to the size of the image block. The JPEG encoder 23a calculates the compression ratio of the main image from the data size before compression of the main image and the data size after compression. The JPEG encoder 23a multiplies the data size of still image data of the sub-image size before compression by the main image compression rate described above, and estimates the data size after compression. The JPEG encoder 23a compares the estimated data size with the size of the thumbnail area. When the estimated data size is smaller than the size of the thumbnail area, the JPEG encoder 23a changes each coefficient of the quantization table to a small value. When the estimated data size is larger than the size of the thumbnail area, the JPEG encoder 23a changes each coefficient of the quantization table to a large value.

  FIG. 11B is a quantization table obtained by multiplying each coefficient of the quantization table of FIG. 11A by 1/2 to reduce the compression effect. FIG. 11C is a quantization table obtained by doubling each coefficient of the quantization table of FIG. 11A in order to increase the compression effect.

  Note that the JPEG encoder 23a may adjust the quantization table so that the encoded data size of the still image data of the sub-image size is slightly smaller than the size of the thumbnail area. This is because the encoded data size of the still image data of the sub-image size is surely made smaller than the size of the thumbnail area and the encoding is completed once. By adjusting in this way, the package processing within the blanking period can be performed more reliably.

  In the above description, it is assumed that the quantization table for the main image and the quantization table for the sub-image are the same. However, even if both are separate tables, the current sub-image quantum is based on the compression ratio of still image data of the main image size and the size of each coefficient of the quantization table for the main image. It is only necessary to estimate the data size after compression when using the quantization table and adjust the quantization table for the sub-image according to the comparison between the estimated size and the size of the thumbnail area.

  In addition, in the encoding process of a moving image frame, the frame is generally stored in the DDR main memory 16 and then encoded. Therefore, the moving image frame is processed with a delay of several frames from the processing of the still image frame. Since the still image frame is a frame cut out from the moving image frame, there is a correlation between them. Therefore, the moving picture codec 20 may refer to the compression rate when the above-described main image quantization table is used. Thereby, the moving image codec 20 can use the moving image compression rate as reference data for analysis before moving image compression performed in, for example, two-pass encoding. By using it as reference data, it is possible to perform more accurate code amount control with a smaller circuit configuration than the normal configuration. Note that the 2-pass encoding is a processing method in which data analysis and compression are performed separately when compressing moving image data. First, moving image analysis is performed in the first process to calculate features and the like, and compression, which is the second process, is performed based on the calculated value. Two-pass encoding takes nearly twice as much time as one-pass encoding in which analysis and compression are performed in a single process, but is characterized in that a high image quality and compression rate can be obtained.

  Furthermore, the moving image codec 20 may adjust the quantization table used for moving image compression with reference to the quantization table for the main image and the compression rate when the table is used. Here, the adjustment of the quantization table means that the value of each coefficient in the table is changed in order to change the compression rate as described above. Thereby, the data size after moving image compression can be made into a desired size.

  The adjustment of the compression rate can also be realized by adjusting the cutoff frequency of the horizontal filter circuit 41 described above in addition to the adjustment of the quantization table. Therefore, the horizontal filter 41 may adjust the cut-off frequency from the relationship between the compression ratio calculated by the JPEG encoder 23a and the thumbnail area. However, in this method, the timing at which the adjustment of the cutoff frequency is reflected is the processing timing of the next frame. For this reason, it is effective when processing videos with relatively few scene changes, but it is better to adjust the quantization table as described above when processing videos with relatively many scene changes. Good. It is also possible to perform both the adjustment of the cutoff frequency in the horizontal filter circuit 41 and the adjustment of the quantization table.

<Generated package in each frame>
Next, a specific example of package processing by the CPU 15 will be described. FIG. 12 is a conceptual diagram showing the state of the work area immediately before starting the package processing. 12A to 12C show the state of the work area in the DDR main memory 16 before the package of each different frame.

  FIG. 12A shows an example in which a slight empty area is generated in the thumbnail area. The CPU 15 writes “FF”, which is ignorable data (referred to as invalid data in the following description) in the empty area. The CPU 15 adjusts the quantization table as described above to adjust the size of the still image data of the sub image size after encoding to the thumbnail area. However, when such a free area occurs, the CPU 15 writes invalid data without performing re-encoding. As a result, the number of encodings is limited to one, and the package process can be started quickly. Furthermore, writing invalid data does not affect the image quality after the EXIF package processing.

  FIG. 12B shows an example in which there is no empty space in the thumbnail area. In this case, the CPU 15 executes the package process without writing invalid data. FIG. 12C shows an example in which a large empty area is generated in the thumbnail area. In this case, the CPU 15 writes invalid data in all the empty areas as shown in the figure, and performs package processing without performing re-encoding.

  Finally, the effect of the imaging apparatus will be described again. As described above, the JPEG encoder 23a compresses still image data of the main image size during the effective period and compresses still image data of the sub image size during the blanking period. That is, the JPEG encoder 23a is shared by the main image processing and the sub image processing. Further, since the CPU 15 performs the sub-image size encoding process and the package process during the blanking period, the CPU 15 can generate an EXIF package (image compression package) in real time. That is, an EXIF package (image compression package) can be generated in real time with a single JPEG encoder 23a configuration.

  Further, the CPU 15 in the imaging apparatus 1 can execute the encoding of the still image data of the sub-image size and the writing to the work area in parallel during the blanking period (FIG. 10A). As a result, the timing for ending the package processing can be advanced, and as a result, the package processing can be reliably ended within the blanking period.

  Further, the JPEG encoder 23a in the imaging apparatus 1 adjusts the quantization table for the sub image based on the compression ratio of the main image. As a result, it is possible to realize a compression rate that matches the thumbnail area (fixed area of the work area).

  Further, the CPU 15 writes an invalid value in the empty area when the compressed data size of the still image data of the sub-image size is smaller than the thumbnail area. Since only one encoding process is performed and an invalid value that does not affect the image quality is written in the empty area, a high-quality image compression package can be quickly generated.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the embodiments already described, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

DESCRIPTION OF SYMBOLS 1 Image pick-up device 11 Lens 12 Image pick-up element 13 Camera signal processing part 14 Zoom / focus control part 15 CPU
16 DDR main memory 17 SD card 18 USB
19 Size converter 20 Video codec 20a Video encoder 20b Video decoder 21 Size converter 21a Main image size converter 21b Sub-image size converter 22 Line memory 22a Line memory 22b Line memory 23 JPEG codec 23a JPEG encoder 24 Video signal processor 25 HDMI
26 LCD
27 selector 27a first input image selection unit 27b second input image selection unit 28a main image control unit 28b sub image control unit 41 horizontal filter circuit 42 horizontal filter circuit 43 horizontal thinning circuit 44 scaler processing line memory controller 45 vertical filter circuit 46 vertical filter circuit 47 vertical thinning circuit 48 horizontal filter circuit 49 horizontal filter circuit

Claims (8)

An image sensor;
A still image frame acquisition unit that acquires a still image frame from the moving image data acquired by the imaging device at an arbitrary timing;
A main image size conversion unit that converts the size of the still image frame acquired by the still image frame acquisition unit in real time to generate main image data;
A sub-image size conversion unit that converts the size of the still image frame acquired by the still image frame acquisition unit in real time to generate sub-image data;
A first line memory for storing the main image data;
A second line memory for storing the sub-image data;
A still image compression unit for compressing data stored in the first or second line memory;
A CPU that generates a compressed package using the compressed data compressed by the still image compression unit;
A main memory that functions as a work area for generating the compressed package and stores various data;
The still image compression unit compresses the main image data during effective area processing in the still image frame, compresses the sub-image data during blanking area processing in the still image frame,
The CPU writes main image compressed data obtained by compressing the main image data in the work area during the effective area processing in the still image frame, and during the blanking area processing in the still image frame, An imaging apparatus, wherein the compressed package is generated by writing sub-image compressed data obtained by compressing sub-image data and predetermined header data.   The CPU uses the header data and the sub-image compressed data that is the sub-image data that has been compressed for generation of the compression package in parallel with the compression process of the previous sub-image data by the still image compression unit. The imaging apparatus according to claim 1, wherein writing is performed in the work area.   The still image compression unit includes the main image data and a compression ratio calculated from the main image compression data, a quantization table used for compressing the main image, a region size for a sub image in the work area, and the sub image The imaging apparatus according to claim 1, wherein a quantization table used for compression of the sub-image data is adjusted based on a data size of the image data.   4. The CPU according to claim 1, wherein the CPU writes the compressed sub-image data in a sub-image area of the work area, and writes invalid data in the empty area when an empty area occurs. The imaging device according to any one of the above. A moving image compression unit for compressing moving image data stored in the main memory;
The moving image compression unit estimates the moving image compression rate based on the main image data, a compression rate calculated from the main image compression data, and a quantization table used for compression of the main image. The imaging device according to any one of 1 to 4.   The moving image compression unit adjusts a quantization table used for moving image compression based on the compression ratio calculated from the main image data and the main image compression data and the quantization table used for compression of the main image. The imaging apparatus according to claim 5, characterized in that:   The imaging apparatus according to claim 3, wherein a sub-image area in the work area has a fixed size. A still image frame acquisition step of acquiring a still image frame from the moving image data acquired by the image sensor at an arbitrary timing;
A main image size conversion step of generating main image data by converting the size of the still image frame acquired in the still image frame acquisition step in real time;
A sub-image size conversion step of generating sub-image data by converting the size of the still image frame acquired in the still image frame acquisition step in real time;
A still image compression step for compressing the main image data or the sub image data stored in the first or second line memory;
A package step of generating a compressed package using the compressed data compressed in the still image compression step,
In the still image compression step, the main image data is compressed during effective area processing in the still image frame, and the sub-image data is compressed during blanking area processing in the still image frame,
In the packaging step, the main image compressed data obtained by compressing the main image data is written to the work area in the main memory during the effective area processing in the still image frame, and the blanking area processing in the still image frame is being performed. In addition, the compressed package is generated by writing sub-image compressed data obtained by compressing the sub-image data and predetermined header data.

Images