JP2009135836A - Digital image radio transmitter and its image data processing method, digital image radio receiver, and digital image radio transmitting and receiving system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital image radio transmitter for quick process with less delay time, and to provide its image data processing method. <P>SOLUTION: The digital image radio transmitter compresses image data of a photographed image for digital radio transmission, wherein the digital image radio transmitter comprises: a temporary memory part which has a memory capacity being smaller than the capacity corresponding to a single frame of the image data of photographed image and sequentially and temporarily stores the image data of photographed image in units of minimum unit regions that constitute a portion of the signal frame and can be separately compressed; an image compression process part which sequentially compresses the image data read in units of minimum unit regions from the temporary memory part; a transmission buffer which accumulates the image data that the image compression process part compresses; and a transmission part which sequentially transmits the image data read from the transmission buffer at a fixed transmission rate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a digital image radio transmission apparatus and an image data processing method for digital radio transmission using the digital image radio transmission apparatus.

  Conventionally, in image data processing for compressing moving image data and transmitting it wirelessly, image data processing has been generally performed in units of one or more frames, based on so-called frames corresponding to a single frame.

  In such image data processing, the image data transmission device temporarily stores image data of a captured image of a subject captured from the camera in a frame memory once via an input signal interface.

  In the frame memory, image data is accumulated until image data corresponding to at least one frame is stored. Then, the image data transmitting apparatus sequentially reads out the stored image data corresponding to one frame from the frame memory and performs compression processing of the image data.

  For this reason, in the conventional image data transmission apparatus, the image data of the captured image sequentially read from the camera is temporarily held in the frame memory until the image data corresponding to one frame is accumulated in the frame memory. It was in a state.

  The time for which the image data is temporarily in the frame memory is expected to be approximately 33 milliseconds at maximum if the frame rate is typically 30 frame seconds (fps).

  On the other hand, in an imaging system that captures and displays a current subject image, for example, a vehicular rear confirmation camera or the like as a typical example, rapid camera image transmission is required in real time without delay.

Therefore, it is preferable that the processing time of the image data including the image data storage time corresponding to one frame described above is shortened as much as possible to transmit / receive image data without delay. However, since an amount corresponding to one frame is used as a reference for image processing, there is a limit corresponding to an accumulation time corresponding to one frame for processing without delay. An example of such image data processing is disclosed in Patent Document 1 below.
JP 2007-124409 A

  Accumulating the image data of the captured image captured from the camera in the frame memory until the image data equivalent to one frame is temporarily stored in the frame memory, as in the past, in order to perform further rapid processing It becomes a limit.

  The present invention has been made in view of the above-described viewpoints, and an object of the present invention is to provide a digital image radio transmission apparatus that can perform quick processing with less delay time, an image data processing method thereof, and the like.

  A digital image radio transmission apparatus according to the present invention is a digital image radio transmission apparatus that compresses image data and performs digital radio transmission, and has a storage capacity smaller than the capacity corresponding to one frame of image data, In addition, a temporary storage unit that sequentially stores temporarily for each minimum unit area that can be compressed and that constitutes a part of one frame, and an image compression process that sequentially compresses image data read from the temporary storage unit for each minimum unit area And a transmission buffer that stores image data compressed by the image compression processing unit, and a transmission unit that sequentially transmits image data read from the transmission buffer at a fixed transmission rate.

  In the digital image radio transmission apparatus according to the present invention, it is preferable that the temporary storage unit has a storage capacity for a horizontal line corresponding to the number of pixels of the minimum unit area in the vertical direction in one frame of image data. , A temporary storage unit that sequentially stores image data for each minimum unit region that constitutes a part of one frame, and the image compression processing unit includes pixels in the vertical direction of the minimum unit region stored in the temporary storage unit The image compression processing unit sequentially compresses image data read out for each minimum unit area from image data for horizontal lines corresponding to the number.

  The digital image radio transmission apparatus according to the present invention preferably further includes first and second processing lines each including an image compression processing unit and a transmission buffer, wherein the first and second processing lines are respectively The processing unit is a processing line that processes each of the plurality of luminance blocks of the minimum unit area by half and each of the plurality of color difference blocks of the minimum unit area by half, and the transmission unit is a first processing line and a second processing line. It is a transmission part which transmits the processed data, It is characterized by the above-mentioned.

  In the digital image radio transmission apparatus according to the present invention, more preferably, the transmission unit is a transmission unit that transmits data at a fixed transmission rate determined for transmission of an audio signal.

  An image data processing method according to the present invention is an image data processing method for compressing image data for digital wireless transmission, and is a minimum unit area capable of compression processing constituting a part of one frame of image data Each time, the temporary storage step of storing the image data in the temporary storage unit sequentially, and before the storage amount of the temporary storage unit in the temporary storage step is equivalent to one frame, the image data of the temporary storage unit is sequentially An image compression processing step of reading and compressing the image.

  In the image data processing method for digital wireless transmission according to the present invention, it is preferable that the temporary storage unit corresponds to the horizontal line corresponding to the number of pixels of the minimum unit area in the vertical direction of one frame of the image data. The image compression processing step has storage capacity, and the image data to be read out for each minimum unit region from the image data for the horizontal line corresponding to the number of pixels that the minimum unit region stored in the temporary storage step has in the vertical direction, It is a step of sequentially compressing.

  A digital image wireless transmission / reception system according to the present invention includes a transmission device that compresses image data and transmits digital wirelessly, and a digital image wireless transmission / reception device that includes a reception device that receives and decompresses image data transmitted by the transmission device. The transmission device has a storage capacity for a horizontal line corresponding to the number of pixels of the minimum unit area in the vertical direction in one frame of the image data, and the image data is converted into a part of one frame. For each minimum unit area that can be compressed, a temporary storage unit that temporarily stores sequentially, and image data for a horizontal line corresponding to the number of pixels that the minimum unit region stored in the temporary storage unit has in the vertical direction, An image compression processing unit that sequentially compresses image data to be read for each minimum unit area, and image data compressed by the image compression processing unit First and second processing lines each including a transmission buffer, and a transmission unit that sequentially transmits the image data processed in the first and second processing lines at a fixed transmission rate. The second processing line is a transmission device that is a processing line that processes each of the plurality of luminance blocks of the minimum unit region by half and each of the plurality of color difference blocks of the minimum unit region by half. A reception unit that receives compressed image data transmitted from the transmission device, a reception buffer that stores image data received by the reception unit, and an image expansion processing unit that sequentially expands image data read from the reception buffer Each of the first and second receiving processing lines includes a storage capacity for a horizontal line corresponding to the number of pixels that the minimum unit area has in the vertical direction. A reception-side temporary storage unit that sequentially and temporarily stores the image data processed in the first and second reception-side processing lines for each minimum unit area, and the first and second reception-side processing lines are Further, the receiving apparatus is a processing line that processes each of a plurality of luminance blocks of the minimum unit area by half and processes each of the plurality of color difference blocks of the minimum unit area by half.

  A digital image radio reception apparatus according to the present invention is a digital image radio reception apparatus that receives compressed image data transmitted by digital radio and performs decompression processing. The reception unit receives the image data; and the reception unit A receiving buffer for storing image data to be received by the image processing apparatus, and first and second receiving side processing lines each including an image decompression processing unit for sequentially decompressing image data read from the reception buffer, and one frame of image data Image data processed by the first and second receiving processing lines has a storage capacity corresponding to the number of pixels in the horizontal direction corresponding to the number of pixels in the vertical direction of the minimum unit area that can be decompressed that constitutes a part. A reception-side temporary storage unit that sequentially and temporarily stores each minimum unit area, and the first and second reception-side processing lines include a plurality of minimum unit areas. While each processing time block by half, and wherein the plurality of chrominance blocks included in the minimum unit region is a process line for each process by half.

  According to the present invention, it is possible to provide a digital image radio transmission apparatus and an image data processing method thereof that perform a quicker process with a reduced delay time.

  The digital image wireless transmission apparatus exemplified in this embodiment is a digital image wireless transmission apparatus that wirelessly transmits image data of an image captured by a camera to a remote place after compression processing.

  This digital image radio transmission apparatus reads image data in units of macroblocks from the temporary storage unit before the image data stored in the temporary storage unit included in the transmission processing unit is equivalent to one frame.

  The transmission processing unit of the digital image radio transmission apparatus sequentially starts compression processing for image data in units of macroblocks read from the temporary storage unit before the storage amount is equivalent to one frame.

  For this reason, the temporary storage unit does not necessarily have a storage capacity corresponding to one frame. Further, it is not necessary to wait for the image data in the temporary storage unit while the image data corresponding to one frame is accumulated in the temporary storage unit.

  In other words, the transmission processing unit of this digital image radio transmission apparatus can shorten the period corresponding to the accumulation time of one frame to a shorter period.

  As a result, the image data can be sequentially sequentially transmitted after the image data is compressed. That is, it is possible to realize a digital image radio transmission apparatus that shortens the delay time corresponding to one frame accumulation time in the frame memory.

  Embodiments will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a conceptual block diagram illustrating the transmission processing unit 11 of the digital image radio transmission apparatus 100 according to the first embodiment of the present invention.

  As illustrated in FIG. 1, the digital image wireless transmission device 100 captures image data of a subject image captured by the camera 10 into a transmission processing unit 11 and performs desired image processing or the like suitable for communication by the transmission processing unit 11. Thereafter, the image data is wirelessly transmitted from the transmission unit 17.

  The transmission unit 17 of the digital image radio transmission apparatus 100 is composed of a radio module or the like, and performs digital radio transmission at high speed.

  In addition, the transmission processing unit 11 quickly performs image data transmission processing so that real-time image data of the subject imaged by the camera 10 can be transmitted from the transmission unit 17 without delay.

  The transmission processing unit 11 includes an input signal interface 12 for inputting analog image data output from a camera 10, typically a camera including a CCD or CMOS solid-state imaging device.

  The transmission processing unit 11 takes in analog image data through the input signal interface 12, and the input signal interface 12 performs conversion into digital image data. The transmission processing unit 11 temporarily stores the image data digitally converted by the input signal interface 12 in the temporary storage unit 13. The temporary storage unit 13 corresponds to a storage unit conventionally configured as a frame memory 43 or the like shown in FIG.

  The temporary storage unit 13 has a storage capacity for 8 × 15 macroblocks that constitute a part of one frame of a captured image captured by the camera 10, typically corresponding to 128 lines.

  Here, the captured image has, for example, a configuration of 240 pixels × 240 lines per frame or field. A macroblock is a basic area that is a minimum unit when processing such as image compression is performed. Typically, one macroblock has a configuration of 16 × 16 pixels. That is, typically one macroblock has 16 lines.

  Therefore, if the captured image is 240 pixels × 240 lines per frame, it has 15 × 15 macroblocks per frame. The temporary storage unit 13 of the transmission processing unit 11 has a storage capacity equivalent to 8 × 15 macroblocks corresponding to approximately half of one frame. For this reason, the time required for storing and storing in the temporary storage unit 13 is also approximately halved. In this case, the temporary storage unit 13 stores 15 macroblocks in the horizontal direction as one macroblock row and 8 macroblocks in the vertical direction, that is, 8 macroblock rows (equivalent to 128 lines of pixels). Capacity.

  Next, the transmission processing unit 11 reads the image data temporarily stored in the temporary storage unit 13 and sequentially compresses the image data using the image compression processing unit 14. The image compression processing unit 14 may perform compression processing by a compression method such as Motion JPEG (Joint Photographic Coding Experts Group).

  The image data compressed by the image compression processing unit 14 is temporarily stored in the transmission buffer 15. The transmission buffer 15 has a storage capacity for one frame, but may have a storage capacity less than that for one frame. The transmission buffer 15 can have a storage capacity corresponding to, for example, 20 macroblocks.

  Next, the digital image wireless transmission device 100 wirelessly transmits the image data once stored in the transmission buffer 15 from the transmission unit 17 via the transmission interface 16. The wireless module constituting the transmission unit 17 can correspond to, for example, an inter IC sound (hereinafter referred to as I2S) system.

  The I2S system is constructed with the intention of transmitting audio signals, and has a high transmission rate. The transmission rate of the I2S system is about 1.5 megabits per second per line input. Accordingly, the transmission rate of the I2S system is, for example, about 3.0 megabits per second for transmission from 2-line input, and about 6 megabits per second for transmission from 4-line input.

  The transmission unit 17 has a high transmission rate as described above. Therefore, it is assumed that the transmission interface 16 reads the image data from the transmission buffer 15 at a high reading rate corresponding to the high transmission rate of the transmission unit 17.

  Therefore, when the transmission interface 16 reads the image data from the transmission buffer 15 at a high reading rate, there is a concern that the image data in the transmission buffer 15 is depleted.

  Therefore, in the transmission buffer 15, dummy data may be stored in the transmission buffer 15 so that reading of image data becomes a so-called read overrun and does not overtake writing. By filling the dummy data into the transmission buffer 15, sufficient data is always present in the transmission buffer 15.

  Further, by storing the dummy data in the transmission buffer 15, the transmission buffer 17 stores the image data corresponding to one macroblock in the transmission buffer 15 while maintaining the high transmission rate. 15 can start reading data. Even if the transmission buffer 15 receives the image data from the image compression processing unit 14 at a desired processing speed, the transmission buffer 15 does not run out of data.

  The digital image radio transmission apparatus 100 does not exclude that other devices are provided between the above-described devices or that other operation processes are performed. The digital image radio transmission apparatus 100 can be configured to interpolate or adjust various processing apparatuses and various devices and their operation processes within an obvious range.

  Here, for comparison, a digital image wireless transmission / reception system 400 configured using a frame memory will be briefly described with reference to FIG.

  The digital image wireless transmission / reception system 400 temporarily stores the image data acquired by the camera 40 in the frame memory 43 via the input signal interface 42 provided in the transmission processing unit 41. The image compression processing unit 44 sequentially compresses the images read from the frame memory 43 and outputs them to the transmission buffer 45.

  The transmission interface 46 reads the image data from the transmission buffer 45 and inputs it to the transmission unit 47, and the transmission unit 47 performs wireless transmission.

  The digital image radio transmission / reception system 400 temporarily stores image data corresponding to one frame of an image acquired by the camera 40 in the frame memory 43. By temporarily storing image data corresponding to one frame in the frame memory 43, an appropriate adjustment is made between the processing when performing various image processing and the like and the output fetching of the image data from the camera 40 in the subsequent steps. It can be carried out. In addition, the digital image wireless transmission / reception system 400 includes the frame memory 43, so that various processes and transmission of image data can be smoothly performed when performing various image processes.

  On the other hand, the digital image radio transmission / reception system 400 inevitably spends time required to store one frame worth of image data sequentially read from the camera 40 in the frame memory 43. The time spent by the digital image radio transmission / reception system 400 for one frame is expected to be about 33 milliseconds at the maximum in the case of 30 fps, for example.

  Therefore, the digital image radio transmission apparatus 100 replaces the frame memory 43 with an 8 × 15 macroblock (typical) so that the subject image can be transmitted more quickly than the digital image radio transmission / reception system 400. Is provided with a temporary storage unit 13 corresponding to 128 lines of one frame. In addition, the temporary storage unit 13 can be configured by a RAM or the like whose line memory is a typical example.

  In the digital image radio transmission apparatus 100, the image compression processing unit 14 starts reading image data from the temporary storage unit 13 before image data corresponding to one frame is accumulated in the temporary storage unit 13. Then, the image compression processing unit 14 sequentially compresses the image data read from the temporary storage unit 13.

  In other words, the temporary storage unit 13 sequentially outputs the image data to the image compression processing unit 14 without waiting for the image data corresponding to one frame to be output from the camera 10. For this reason, it is possible to shorten the time corresponding to the time required for storing image data for one frame.

  When the temporary storage unit 13 stores image data equivalent to 8 × 15 macroblocks (typically 128 lines of one frame), which is about half of one frame, the image data is sent to the image compression processing unit 14. When the output starts, the time required for accumulation becomes about half of the accumulation time corresponding to one frame.

  Next, operation processing of the digital image radio transmission apparatus 100 will be described with reference to FIG. FIG. 3 is a conceptual flow chart showing the processing flow of the digital image radio transmission apparatus 100.

(Step S31)
The digital image wireless transmission device 100 determines whether there is an instruction to capture a subject image. For example, when the digital image wireless transmission device 100 is configured as a vehicle rear confirmation camera, the digital image wireless transmission device 100 detects that there is an imaging instruction from the driver of the vehicle or that the vehicle is set to the reverse gear. To determine whether or not imaging is possible.

  When the digital image radio transmission apparatus 100 captures an image, the process proceeds to step S32. On the other hand, if the digital image radio transmission apparatus 100 does not capture an image, the process waits in step S31.

(Step S32)
The power supply of the camera 10 of the digital image radio transmission apparatus 100 is turned on to start up preparation for image capture. The digital image radio transmission apparatus 100 prepares for image acquisition by initializing an initial value setting operation or the like when the camera 10 is initially set.

(Step S33)
The camera 10 of the digital image radio transmission apparatus 100 starts capturing a subject image. For example, when the camera 10 is composed of a solid-state image sensor such as a CCD or a CMOS image sensor, the camera 10 photoelectrically converts incident light from a subject into an electrical signal by the solid-state image sensor.

(Step S34)
The camera 10 sequentially outputs electric signals obtained by photoelectrically converting light from the subject via the input signal interface 12. Typically, the camera 10 outputs image data for each macroblock having 16 × 16 pixels per macroblock.

(Step S35)
The temporary storage unit 13 of the transmission processing unit 11 sequentially stores the image data output from the camera 10 for each macroblock via the input signal interface 12.

(Step S36)
The transmission processing unit 11 of the digital image radio transmission apparatus 100 determines whether or not the image data stored in the temporary storage unit 13 has a predetermined storage capacity. When the storage capacity of the temporary storage unit 13 is equivalent to 8 × 15 macroblocks (typically, 128 lines per frame), whether or not image data equivalent to 8 × 15 macroblocks has been stored. Judging.

  In addition, you may comprise the temporary memory | storage part 13 with a line memory etc., for example. When the temporary storage unit 13 is configured as a line memory, the line memory is configured in two blocks so that writing and reading to the same storage area do not overlap at the same time. Also, a dual port configuration may be used in order to read and write at high speed.

  If image data corresponding to 8 × 15 macroblocks is stored in the temporary storage unit 13, the process proceeds to step S37. If the image data equivalent to 8 × 15 macroblocks is not stored in the temporary storage unit 13, the process returns to step S35.

(Step S37)
The transmission processing unit 11 of the digital image radio transmission apparatus 100 starts transmitting the image data in the temporary storage unit 13 to the image compression processing unit 14. Here, the transmission processing unit 11 sequentially transmits the image data to the image compression processing unit 14 in units of macro blocks even if the image data corresponding to one frame is not stored in the temporary storage unit 13.

  That is, the temporary storage unit 13 sequentially outputs the image data to the image compression processing unit 14 in units of macroblocks before the accumulation time for one frame has elapsed since the start of storage of the image data in step S35. For this reason, the digital image radio transmission apparatus 100 can shorten the time from the start of image data storage in step S35 to the start of image data output in accordance with the time required for accumulation.

(Step S38)
The image compression processing unit 14 sequentially compresses the image data read from the temporary storage unit 13 for each macroblock.

(Step S39)
The transmission processing unit 11 sequentially stores the image data compressed by the image compression processing unit 14 in the transmission buffer 15. The transmission buffer 15 does not necessarily have a storage capacity equivalent to a compressed image corresponding to one frame of a captured image.

  The optimum value of the storage capacity of the transmission buffer 15 can be determined under a balance between the output transmission rate to the transmission unit 17 and the input transmission rate from the image compression processing unit 14. When the transmission unit 17 has an I2S high-speed transmission rate, the transmission buffer 15 can have a storage capacity equivalent to several tens of macroblocks. Typically, the transmission buffer 15 can output image data to the transmission interface 16 when image data corresponding to, for example, about 20 macroblocks is accumulated.

(Step S3a)
The digital image radio transmission apparatus 100 sequentially transmits image data by the transmission unit 17 via the transmission interface 16.

(Step S3b)
The digital image radio transmission apparatus 100 determines whether to end the imaging. The digital image radio transmission apparatus 100 proceeds to step S3c when the imaging is finished. Also, the digital image radio transmission apparatus 100 returns to step S33 if the imaging is not completed.

(Step S3c)
The digital image radio transmission apparatus 100 turns off the power of the camera 10 based on the operation of the driver of the vehicle.

  As described above, the digital image radio transmission apparatus 100 does not require time for storing one frame of image data sequentially read from the camera 10 before image processing such as image compression processing. For this reason, the digital image radio transmission apparatus 100 can perform quick image data transmission processing with reduced delay.

  Next, a digital image wireless transmission / reception system 200 in which the image compression processing steps and the like of the digital image wireless transmission device 100 are parallelized will be described in a second embodiment.

(Second embodiment)
FIG. 2 is a block conceptual diagram showing a configuration of a digital image radio transmission / reception system 200 according to the second embodiment.

  The transmission processing unit 21 of the digital image wireless transmission / reception system 200 includes a temporary storage unit 23 for 16 lines to which image data is input from the input signal interface 22 instead of the frame memory described above. When one frame is composed of 240 × 240 pixels and one macroblock is 16 × 16 pixels, the temporary storage unit 23 has a storage capacity of exactly one macroblock row (15 macroblocks).

  The transmission processing unit 21 of the digital image wireless transmission / reception system 200 includes a first processing line including an image compression processing unit 24, a transmission buffer 25, and a transmission interface 26. The transmission processing unit 21 of the digital image wireless transmission / reception system 200 has a second processing line including an image compression processing unit 28, a transmission buffer 29, and a transmission interface 2a.

  Each of the transmission buffers 25 and 29 typically stores the compressed image data for one frame in order according to the order of transmission from the image compression processing units 24 and 28. Each of the transmission buffers 25 and 29 reads image data via the transmission interfaces 26 and 2a and starts transmission when compressed data for 16 lines is stored.

  The digital image radio transmission / reception system 200 can process the image data corresponding to 16 lines sequentially stored in the temporary storage unit 23 in parallel by the amount corresponding to 8 lines in the first and second processing lines.

  For this reason, the transmission processing unit 21 of the digital image wireless transmission / reception system 200 substantially doubles the processing capability of the image processing step, and thus the processing time per image data amount is approximately halved.

  The allocation of image data to each of the first and second processing lines will be further described in detail using a typical example of a macroblock shown in FIG. FIG. 5A is a diagram illustrating a typical relationship between one frame and a macroblock. FIG. 5B is a diagram for explaining six blocks constituting one macro block.

  As shown in FIG. 5A, one frame (or one field) of a captured image captured by the camera 20 is configured by 240 × 240 pixels, for example. The digital image wireless transmission / reception system 200 performs processing for each macroblock (macroblock intra) corresponding to the minimum area of compression processing in one frame when performing image coding processing such as compression processing. That is, it can be said that the macroblock is the minimum image coding area that can be subjected to image compression processing independently. A typical example is JPEG using DCT (Discrete Cosine Transform).

  As shown in FIG. 5A, the macroblock 51 can be configured as 16 × 16 pixels, for example. In the example shown in FIG. 5A, 15 × 15 macro blocks 51 exist in one frame. The image data is sequentially read in the horizontal direction for each macroblock 51 (right direction in FIG. 5A). When image data corresponding to 15 macroblocks in the horizontal direction, that is, 16 lines in the horizontal direction are sequentially read out, 15 macroblocks in the vertical direction (downward in FIG. 5A) (the second row of macroblocks). Minute) of image data is read sequentially for each macroblock (from left to right in FIG. 5A).

  Further, as shown in FIG. 5B, the macro block 51 includes four luminance (Y) blocks and two color difference blocks. The four luminance blocks included in the macro block 51 are blocks each composed of 8 × 8 pixels, which are described as Y0, Y1, Y2, and Y3. The two color difference (C) blocks included in the macroblock 51 are blocks each composed of 8 × 8 pixels, which are described as Cb52 and Cr53.

  The transmission processing unit 21 of the digital image wireless transmission / reception system 200 is configured so that the deviation of image data is reduced between the first processing line and the second processing line, and the processing data amount is balanced. Allocate image data to each processing run.

  Typically, the transmission processing unit 21 of the digital image radio transmission / reception system 200 causes the first processing line to process Y0 and Y1 luminance data and Cb52 color difference data. Further, the transmission processing unit 21 of the digital image wireless transmission / reception system 200 causes the second processing line to process the luminance data of Y2 and Y3 and the color difference data of Cr53. The blocks to be processed on the first and second processing lines are not limited to this example, and may be set to be arbitrarily assigned.

  As a result, a data configuration suitable for image compression processing of 4: 1: 1 sampled image data can be achieved. Even when there is a considerable amount of data imbalance between the luminance data Y0, Y1, Y2, Y3 and the color difference data Cb52, Cr53, the first processing line and the second processing line The amount of processing data can be almost the same. Note that the amount of image data after the compression process is somewhat different depending on the image data before the compression process, but the first processing line and the second processing line are almost the same processing by the above-described allocation. Can with load.

  Therefore, the image data output from the temporary storage unit 23 for each macroblock 51 is allocated to the first processing line and the second processing line, and the images are quickly and simultaneously processed in each processing line. Desired processing such as compression processing is performed.

  The image compression processing units 24 and 28 can alternately process a luminance (Y) signal (2 blocks) and a color difference (C) signal (1 block) for each macroblock. For this reason, when it is necessary to switch the quantization table, a code for declaring the quantization table to be selected and applied may be added in the head region (so-called header or the like) of the corresponding image data. For example, the quantization table may be appropriately selected from a predetermined quantization table set in advance.

  Also, when the quantization table is enlarged / roughened in response to an increase in the amount of image data depending on the image on the transmission side, a declaration code is assigned to the marker at the beginning of the frame, corresponding to the degree of coarseness. The information of the quantization table can be sent to the receiving side.

  The transmission unit 27 sequentially transmits image data acquired from the transmission interfaces 26 and 2a at a constant high-speed transmission rate of about 3 megabits per second by the I2S method. Therefore, the transmission processing unit 21 of the digital image wireless transmission / reception system 200 can quickly process the image data captured from the camera 20 without temporarily retaining the image data. As described above, the digital image wireless transmission / reception system 200 transmits the compressed image data at a high transmission rate.

  Other configurations, operations, and processes of the transmission processing unit 21 are the same as those already described in the digital image radio transmission apparatus 100, and are therefore omitted.

  Next, the reception processing unit 2c of the digital image wireless transmission / reception system 200 will be briefly described. The reception processing unit 2c sequentially performs a decoding process on the image data received by the reception unit 2b by parallel processing similar to that of the transmission processing unit 21.

  The reception processing unit 2c has a first reception processing line including a reception interface 2d, a reception buffer 2e, and an image expansion processing unit 2f. The reception processing unit 2c includes a second reception processing line including a reception interface 2i, a reception buffer 2j, and an image expansion processing unit 2k.

  The image data sequentially received by the receiving unit 2b is appropriately allocated to the above-described first reception processing line and second reception processing line, and is simultaneously processed in parallel in each reception processing line. That is, the luminance data Y0, Y1 and the color difference data Cb52 processed in the first processing line of the transmission processing unit 21 are subjected to, for example, image expansion processing for each block in the first reception processing line of the reception processing unit 2c. Done. Further, the luminance data Y2, Y3 and the color difference data Cr53 processed in the second processing line of the transmission processing unit 21 are subjected to, for example, image expansion processing for each block in the second reception processing line of the reception processing unit 2c. Done.

  The image data processed in each reception processing line is sequentially stored for each macroblock in the temporary storage unit 2g having a storage capacity for 16 lines. The digital image wireless transmission / reception system 200 performs processing suitable for display on the image data temporarily stored in the temporary storage unit 2g via the display signal interface 2h. Also, the digital image wireless transmission / reception system 200 displays the image data processed through the display signal interface 2h or the like as an image on the display unit 21.

  For this reason, the digital image wireless transmission / reception system 200 performs transmission with reduced delay of image data captured from the camera 20 and realizes display on the display unit 21 with reduced delay. Therefore, the digital image wireless transmission / reception system 200 is suitable for low-delay display of real-time images, and is particularly suitable for a vehicle rear confirmation system and the like.

  Here, for comparison, the reception processing unit 49 of the digital image radio transmission / reception system 400 configured using a frame memory will be briefly described with reference to FIG.

  The reception processing unit 49 of the digital image wireless transmission / reception system 400 temporarily stores the image data received by the reception unit 48 in the reception buffer 4b via the reception interface 4a. The image decompression processing unit 4c decompresses the image data stored in the reception buffer 4b and sequentially transmits it to the frame memory 4d.

  The frame memory 4d continues to store image data until image data corresponding to one frame is stored. The display signal interface 4e sequentially reads image data corresponding to one frame stored in the frame memory 4d and causes the display unit 4f to display an image.

  Therefore, in the digital image radio transmission / reception system 400, the frame memory 4d requires an accumulation time corresponding to one frame. In other words, the digital image radio transmission / reception system 400 performs image compression on the transmission side and image expansion processing on the reception side as processing units of one frame or more (or one field or more). For this reason, a delay corresponding to one frame or more occurs on each side of the transmission side and the reception side.

  On the other hand, even if the accumulation time corresponding to one frame is, for example, about 33 milliseconds, the digital image radio transmission / reception system 200 can perform accumulation quickly because the accumulation time can be about 1 millisecond corresponding to 16 lines. Is possible.

  In addition, the digital image wireless transmission / reception system 200 can maintain a constant latency (delay amount) regardless of the image size, and can perform continuous processing using the temporary storage units 23 and 2g corresponding to 16 lines. Even if the image size is, for example, 400 lines or 480 lines, the same configuration and processing can be achieved.

  In addition, the digital image radio transmission / reception system 200 can realize downsizing and space saving of the transmission processing circuit and the like by reducing the storage capacity. The digital image radio transmission / reception system 200 can also realize cost reduction by reducing the storage capacity.

  In addition, the transmission unit 27 can sequentially transmit image data input simultaneously and in parallel independently from the first and second processing lines by the I2S method. That is, the digital image wireless transmission / reception system 200 does not require image data adjustment by a write arbitration circuit or the like to the transmission buffer 45 while performing parallel processing by the first and second processing lines. Therefore, the digital image radio transmission / reception system 200 can be a simple and low-cost transmission buffer 45 or transmission unit 27.

  In addition, although the digital image wireless transmission / reception system 200 has been described as having two processing lines as parallel processing, the present invention is not limited to this. Three or more parallel processings may be performed by three or more processing lines. In this case, the transmission unit 27 can set a transmission rate that is an integral multiple corresponding to the number of processing lines of 1.5 megabits per second.

  The digital image wireless transmission / reception system 200 can realize a quick image compression process and the like without setting a high clock frequency by parallelizing the compression process and the like. Further, since it is not necessary to set the clock frequency high, it is possible to reduce the influence on the DCT equipped with a multiplier.

  In addition, since the image compression process can be performed quickly even when the clock frequency is kept the same, it is possible to find a time margin sufficient to repeatedly perform the DCT process. For this reason, it is possible to determine whether the image compression is a simple image or a complicated image and perform the quantization process again.

  Further, the digital image wireless transmission device and the like described in the present embodiment have been described as being wireless communication devices, but the present invention is not limited to this and may be applied to wired communication. Further, as described in the digital image wireless transmission / reception system 200, a process of sequentially performing image compression processing and image expansion processing using a temporary storage unit as a 16-line memory may be applied to a wired communication system.

  If the digital image wireless transmission / reception system 200 is applied to a wired communication system, a digital image wireless transmission / reception system in which the number of communication lines is reduced by serial communication can be obtained. Further, in such wired communication, the amount of image data is appropriately reduced by appropriate compression processing, so that even if the original data is a large amount of image data, it can be transmitted at a low transmission rate. In addition, it is preferable to apply the digital image wireless transmission / reception system 200 to wired communication because long-distance communication is possible.

  In addition, the digital image radio transmission apparatus can be used by appropriately changing the configuration, operation, and processing within an obvious range.

  (Additional remark 1) The image data processing method of this invention is an image data processing method for compressing the image data of the picked-up image taken in from a camera, and carrying out digital wireless transmission, Comprising: A part of image data of one frame of a picked-up image is obtained. Temporary storage step for sequentially storing each macroblock in the temporary storage unit, and before the storage amount of the temporary storage unit in the temporary storage step is equivalent to one frame, the image data of the temporary storage unit is stored for each macroblock The temporary storage unit has a storage capacity corresponding to 16 lines in the image data of one frame of the captured image, and the image compression processing step This is a process of sequentially compressing image data to be read for each macro block from image data corresponding to 16 lines stored in the storage process. The processing step includes a first image compression processing step of sequentially compressing two Y blocks and one C block among the four Y blocks and two C blocks included in the macroblock, and the other two Y blocks. A second image processing step of sequentially compressing the block and another one of the C blocks, and the first image compression processing step and the second image compression processing step are processed in parallel. The image data processing method for digital wireless transmission can be obtained.

  (Supplementary Note 2) A digital image wireless transmission / reception system including a transmission device that compresses image data of a captured image captured from a camera and digitally transmits the data, and a reception device that receives and decompresses the image data transmitted by the transmission device The transmission apparatus has a storage capacity corresponding to 16 lines of one frame of image data of the captured image, and temporarily stores the image data of the captured image for each macroblock constituting a part of one frame. A temporary storage unit, an image compression processing unit that sequentially compresses image data to be read for each macroblock from image data corresponding to 16 lines stored in the temporary storage unit, and image data that is compressed by the image compression processing unit And a transmission unit that sequentially transmits image data read from the transmission buffer at a fixed transmission rate. In addition, each of the image compression processing unit and the transmission buffer includes a first image compression processing line and a second image compression processing line each including an image compression processing unit and a transmission buffer so as to perform parallel processing as a set. Of the four Y blocks and two C blocks of the block, two Y blocks and one C block are processed by the first image compression processing line, and the other two Y blocks and the other one C block are processed. A transmission device that processes a block with a second image compression processing line, the reception device receiving a compressed image data transmitted from the transmission device, and storing image data received by the reception unit The reception buffer, the image expansion processing unit that sequentially decompresses the image data read from the reception buffer, and the image data that the image decompression processing unit decompresses Each of the image decompression processing unit and the reception buffer so that the processing in the image decompression processing unit and the reception buffer is set as parallel processing. And a digital image wireless transmission / reception system characterized in that the receiving apparatus includes first and second image expansion processing lines.

It is a block conceptual diagram explaining the transmission processing part concerning a first embodiment. It is a block conceptual diagram which shows the digital image radio | wireless transmission / reception system concerning 2nd embodiment. It is a flow conceptual diagram which shows the processing flow of a digital image radio | wireless transmission apparatus. It is a block conceptual diagram which shows the structural example using a frame memory. It is a figure explaining a macroblock typical example.

Explanation of symbols

10..Camera, 11 .... Transmission processing unit, 12 .... Input signal interface, 13 .... Temporary storage unit, 14 .... Image compression processing unit, 15 .... Transmission buffer, 16 .... Transmission interface, ... Transmission unit 20 .. Camera 21.. Transmission processing unit 23.. Temporary storage unit 24.. Image compression processing unit 25 25 Transmission buffer 26 Transmission interface 27 Transmission unit 28 ..Image compression processing unit 29..Transmission buffer 40..Camera 42..Input signal interface 43..Frame memory 44..Image compression processing unit 45..Transmission buffer 46 .. Transmission interface 47... Transmission unit 48.. Reception unit 49.. Reception processing unit 51.. Macroblock 52.. Cb 53.

Claims (8)

A digital image radio transmission apparatus for compressing image data and digital radio transmission,
A temporary storage unit that has a storage capacity smaller than a capacity corresponding to one frame of the image data, and temporarily stores the image data for each minimum unit area that forms a part of the one frame and that can be compressed; ,
An image compression processing unit that sequentially compresses the image data read from the temporary storage unit for each of the minimum unit areas;
A transmission buffer for storing the image data compressed by the image compression processing unit;
A transmission unit that sequentially transmits the image data read from the transmission buffer at a fixed transmission rate;
A digital image radio transmission apparatus comprising: The digital image radio transmission apparatus according to claim 1.
The temporary storage unit
The minimum unit area having a storage capacity for a horizontal line corresponding to the number of pixels in the vertical direction in the minimum unit area of one frame of the image data, and constituting the image data as a part of the one frame Each is a temporary storage unit for temporarily storing
The image compression processing unit
An image compression processing unit that sequentially compresses image data to be read for each minimum unit region from image data for horizontal lines corresponding to the number of pixels of the minimum unit region in the vertical direction stored in the temporary storage unit A digital image radio transmission apparatus characterized by that. The digital image radio transmission apparatus according to claim 2,
First and second processing lines each including the image compression processing unit and the transmission buffer,
Each of the first and second processing lines is a processing line that processes each of the plurality of luminance blocks included in the minimum unit area by half and processes each of the plurality of color difference blocks included in the minimum unit area by half. ,
The transmission unit is a transmission unit that transmits data processed in the first and second processing lines.
A digital image radio transmission apparatus characterized by the above. The digital image radio transmission apparatus according to any one of claims 1 to 3,
The transmitting unit is a transmitting unit that transmits data at a fixed transmission rate determined for transmission of an audio signal.
A digital image radio transmission apparatus characterized by the above. An image data processing method for compressing image data for digital wireless transmission,
Temporary storage step of sequentially storing in a temporary storage unit for each minimum unit area capable of compression processing constituting a part of one frame of the image data;
An image compression processing step of sequentially reading out and compressing the image data of the temporary storage unit for each of the minimum unit areas before the storage amount of the temporary storage unit in the temporary storage step is equivalent to one frame; ,
An image data processing method for digital wireless transmission characterized by comprising: The image data processing method for digital wireless transmission according to claim 5,
The temporary storage unit
A storage capacity for a horizontal line corresponding to the number of pixels of the minimum unit area in the vertical direction in one frame of the image data,
The image compression processing step includes
The step of sequentially compressing image data to be read for each of the minimum unit areas from the image data of horizontal lines corresponding to the number of pixels of the minimum unit area stored in the vertical direction stored in the temporary storage step. An image data processing method for digital wireless transmission as a feature. A digital image wireless transmission / reception system comprising: a transmission device that compresses image data and transmits digital wirelessly; and a reception device that receives and decompresses image data transmitted by the transmission device,
The transmitter is
The image data has a storage capacity for a horizontal line corresponding to the number of pixels of the minimum unit area in the vertical direction in one frame of the image data, and the image data can be compressed to constitute a part of the one frame A temporary storage unit that sequentially stores temporarily for each minimum unit area,
Image compression processing for sequentially compressing the image data read out for each of the minimum unit areas from image data for horizontal lines corresponding to the number of pixels of the minimum unit area in the vertical direction stored in the temporary storage unit And first and second processing lines each including a transmission buffer for storing the image data compressed by the image compression processing unit,
A transmission unit that sequentially transmits the image data processed in the first and second processing lines at a fixed transmission rate, wherein the first and second processing lines have a plurality of luminances included in the minimum unit area. A transmission device that is a processing line that processes each of the blocks by half and processes each of the plurality of color difference blocks in the minimum unit area by half.
The receiving device is:
A receiving unit for receiving compressed image data transmitted from the transmitting device;
First and second reception processing lines each including a reception buffer for storing the image data received by the reception unit, and an image expansion processing unit for sequentially expanding the image data read from the reception buffer;
The minimum unit area has a storage capacity for a horizontal line corresponding to the number of pixels in the vertical direction, and the image data processed in the first and second receiving processing lines is And the receiving side temporary storage unit for temporarily storing the first and second receiving side processing lines, each processing a plurality of luminance blocks of the minimum unit area by half each, and the minimum unit area Is a receiving device that is a processing line that processes each of a plurality of color difference blocks of each half.
A digital image radio transmission / reception system. A digital image radio receiving apparatus for receiving compressed image data transmitted by digital radio transmission and performing decompression processing,
A receiving unit for receiving the image data;
First and second receiving side processing lines each including a reception buffer for storing the image data received by the reception unit, and an image expansion processing unit for sequentially expanding the image data read from the reception buffer;
The first and second receiving side processing has a storage capacity corresponding to the number of pixels in the horizontal direction corresponding to the number of pixels in the minimum unit area that can be decompressed, constituting a part of one frame of the image data. A reception-side temporary storage unit that sequentially stores the image data processed in a line for each of the minimum unit areas, and the plurality of first and second reception-side processing lines are included in the minimum unit area. A digital image radio receiving apparatus characterized in that a processing line for processing half of each of the luminance blocks and processing each of the plurality of color difference blocks of the minimum unit area by half.

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