CN101742300B - System and method for compressing satellite images with low bit rate - Google Patents
System and method for compressing satellite images with low bit rate Download PDFInfo
- Publication number
- CN101742300B CN101742300B CN 200810226721 CN200810226721A CN101742300B CN 101742300 B CN101742300 B CN 101742300B CN 200810226721 CN200810226721 CN 200810226721 CN 200810226721 A CN200810226721 A CN 200810226721A CN 101742300 B CN101742300 B CN 101742300B
- Authority
- CN
- China
- Prior art keywords
- module
- coefficient
- image
- code stream
- coding
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Compression Or Coding Systems Of Tv Signals (AREA)
- Compression Of Band Width Or Redundancy In Fax (AREA)
Abstract
The invention discloses a system and a method for compressing satellite images with low bit rate. The system comprises a control module, a wavelet transformation module, a CCSDS scanning coding module and a code stream splicing module. In the system and the method, image data are divided into a plurality of 32*32 (or 64*64 and 128*128) small images; then, the small images are transmitted into the wavelet transformation module, the scanning coding module and the code stream splicing module for obtaining compressing code streams. The wavelet transformation module, the scanning coding module and the code stream splicing module are used for line production among image blocks; and the scanning coding module is used for the line production along bit planes. The compressing effect of the system and the method for compressing the images is between JPEG 2000 and EZW; when the compression is carried out at a low bit rate, the compressing effect is equivalent to JPEG2000; a decoding re-synchronization mechanism is adopted for preventing error codes of space data from diffusing in transmission, with low power consumption; and extensively used parallel operation and a line structure increase the processing speed of a chip and meet the macro compressing requirement of the satellite images.
Description
Technical field
The present invention relates to the image compression field, particularly relate to a kind of spaceborne image compression system of low bit rate SPACE APPLICATION, that meet the CCSDS standard and method of being suitable for.
Background technology
In recent years; Fast development along with China's Aerospace Technology; On the star sensing and detecting devices on quantity still is precision all than increasing greatly in the past; The image data amount that satellite obtains in effective observation time section is increasing, and these " magnanimity " view data have brought great pressure for storage and transmission.Because the capacity of memory is limited by the infinitely increase of restriction of aspects such as volume, weight, power consumption on the star; The transmittability of same clock star-ground down link is limited by the limited visual time restriction of transmission bandwidth and ground station, so just become an indispensable link of data processing on the star in the rail image compression.Just become the inevitable choice that solves spatial data storage and transmission problem and develop high performance spaceborne low bit rate image compression system.
Star loaded camera often adopts to push away sweeps the mode images acquired; The bit-depth of pixel is generally 8～16bits; Data transfer rate is big; This just requires spaceborne image compression system processing capability in real time strong, requires system must satisfy requirements such as volume is little, in light weight, low in energy consumption simultaneously, and the number abominable of delivering a letter in space requires the error-resilient performance of compression algorithm high in addition.3 set chained lists that need add use based on the spiht algorithm of wavelet transformation make storage demand big; The spiht algorithm of no chained list has reduced storage demand, has also reduced compression performance simultaneously; And general JPEG2000 is difficult to be applicable to space field because of its algorithm too complicated (each pixel operation times is above 300 times).General algorithm generally is to do convolution with whole frame image data when realizing wavelet transformation, and calculation of complex and memory space that need be a large amount of can't satisfy the spatial image compressing requirement.To this problem, F.W.Wheeler and W.A.Pearlman propose the spiht algorithm that piecemeal independently carries out.(The Consultative Committee forSpace Data Systems, the FIY wavelet transformation and the strip-type JPEG2000 compression algorithm that CCSDS) proposed once are the transition coding based on fixing row view data in consultative committee for space data system.The ICER algorithm of JPL also is conversion of segmentation independence and coding.The spatial image that divides block transform coding to be fit to push-scanning image is handled, and can reduce requirement to memory capacity, help to realize the hardware system of best area-time-power, and can limit the error code diffusion.Can greatly reduce master, the objective quality of reconstructed image yet each piece independently carries out " blocking effect " brought of wavelet transformation (data outside the block boundary are obtained by cycle data continuation in the piece or mirror image continuation), this situation is particularly serious when low bit rate compresses.
Summary of the invention
The object of the invention is; Spaceborne image compression processing system of a kind of low bit rate and method are provided; To solve the high power compression problem of image in the SPACE APPLICATION, develop a kind of bottleneck problem SPACE APPLICATION, that FPGA image compression chip that meet the CCSDS122.0-B-1 standard, that have best area-time-power is stored and transmitted with the solution spatial data that is suitable for.
In order to achieve the above object, the present invention proposes spaceborne image compression processing system of a kind of low bit rate and method.This system and method compresses the small images that original image is divided into 32*32 (perhaps 64*64,128*128); (specifically dividing block size to be decided by concrete application demand) is technological to the bit-plane coding that DC coefficient carries out lossless coding, ac coefficient employing combination entropy coding; Between compression performance and encoder complexity, obtain compromise, be fit to SPACE APPLICATION.
The spaceborne image compression processing system of a kind of low bit rate provided by the invention comprises:
One control module is used to coordinate the running of image block, wavelet transformation, scanning encoding and code stream concatenation module;
One wavelet transformation module is used for the view data of input is carried out band decomposition, does the processing of decorrelation, obtains the coefficient of wavelet decomposition of this view data, and this coefficient of wavelet decomposition is sent into CCSDS scanning encoding module.
One CCSDS scanning encoding module is used for coefficient of wavelet decomposition is scanned and encodes, and coding is sent into the code stream concatenation module.And
One code stream concatenation module, being used for the coding of importing is spliced into the word is the code stream of unit.
Wherein, said control module is divided into view data the small images of 32*32 (perhaps 64*64,128*128) earlier, then this small images is sent into the wavelet transformation module and carries out wavelet transformation.Be the flowing water between image block and the image block between wavelet transformation module and scanning encoding module, the code stream concatenation module; The scanning encoding module is to carry out flowing water between each bit-planes.
Wherein, said control module is at first through judging the synchronous head and the length and width of image, the frame head information of compression multiple, the position No. of computing block first (piece top left corner pixel); Row through the piece interior pixel is set number and row number are judged the progress that image reads then; At last through position No., image first address, ram numbering in the piece, (perhaps 4096,16384) the individual data of exporting 1024 are continuously accomplished the blocking process to view data.The core design of this system is to carry out computing to small images, adopts the heavy synchronization mechanism of decoding can prevent the error code diffusion in the spatial data transmission, low in energy consumption (≤1watt/Msamples/sec); In addition, the processing speed (data processing speed when frequency is 100MHz is 20Mpixels/s) that concurrent operations of adopting in a large number and flowing structure have improved system.
Wherein, said wavelet transformation module adopts foldable structure, utilize two one-dimensional wavelet transforms nuclears successively to the data of input go, rank transformation, finally obtain the 2-d wavelet decomposition coefficient.Be characterized in having reused one-dimensional wavelet transform nuclear, saved logical resource on the sheet,, alleviated the complexity of addressing through adopting two block caches.This framework with go simultaneously, specific rate is slower mutually for the rank transformation framework, but the processing speed of wavelet transformation is not the bottleneck of whole compressibility, it is a kind of rational way that sacrifice speed saves that logical resource takies.Simultaneously, adopt two two-port RAMs, buffer memory MemoryA and buffer memory MemoryB have used free IP core, need not external RAM, have not only optimized design, have improved the speed of service, have also shortened the development time.
Wherein, DC coefficient coding and the parallel processing of ac coefficient coding in the said CCSDS scanning encoding module.
Wherein, said CCSDS scanning encoding module comprises: block scan module and entropy coding module.
The scanning sequency of said block scan inside modules is by first grandson's coefficient, the day after tomorrow subsystem number, last father's coefficient, and single pass obtains the ac coefficient degree of depth of 16 " j-trees "; The escape word of 16 j-trees of parallel computation; Wherein, the memory space buffer memory opened up in addition in the escape word greater than 1 bit;
Said entropy coding module calculation code option time-division two parts parallel processing, first accomplishes the reading of the escape word copy of 0～7 j-tree, and second portion is accomplished reading the escape word copy of 8～15 j-trees.
Wherein, said block scan module is to 16 j-trees and line scanning; Said entropy coding module is in the process of coding, and it is the optimum code option that the code word size that travels through all the encoding options is selected the minimum option of code length, then according to the option coding of tabling look-up.
Wherein, the data among said wavelet transformation module and the block scan module reuse Dwt_ram; DC coefficient code stream that said scanning encoding module produces and ac coefficient encoding code stream get into the code stream concatenation module through the alternative selector; The code stream that original image frame header that transmits via inner buffer FIFO1 and code stream concatenation module obtain gets into inner buffer FIFO2 output through the alternative selector; Wherein, said alternative selector is controlled by control module.
Wherein, said code stream concatenation module is added digit counter in the link of code word splicing and output, if counter has satisfied compression ratio, then stops coding at once.Can save unnecessary work like this, reduce power consumption.
The spaceborne image compress processing method of a kind of low bit rate provided by the invention may further comprise the steps:
(1) control module is sent view data into the wavelet transformation module by the order ground of original image;
(2) the wavelet transformation module is carried out band decomposition to the view data of input, does the processing of decorrelation, obtains the coefficient of wavelet decomposition of this view data, and this coefficient of wavelet decomposition is sent into CCSDS scanning encoding module;
(3) CCSDS scanning encoding module scans coefficient of wavelet decomposition and encodes, and coding is sent into the code stream concatenation module;
(4) to be spliced into the word be the code stream of unit to the coding that will import of code stream concatenation module;
Wherein, said control module is divided into view data the small images of 32*32 (perhaps 64*64,128*128) earlier, then this small images is sent into the wavelet transformation module and carries out wavelet transformation.Be the flowing water between image block and the image block between wavelet transformation module and scanning encoding module, the code stream concatenation module; The scanning encoding module is to carry out flowing water between each bit-planes.
Wherein, said step (1) further comprises: control module is at first through judging the synchronous head and the length and width of image, the frame head information of compression multiple, the position No. of computing block first (piece top left corner pixel); The row number that the piece interior pixel is set then and row number are used to the progress of judging that image reads; At last through piece position No., image first address, ram numbering, (perhaps 4096,16384) the individual data of exporting 1024 continuously are to the step of wavelet transformation module.
Wherein, said step (2) further comprises: the wavelet transformation module adopts foldable structure, utilize two one-dimensional wavelet transforms nuclears successively to the data of input go, rank transformation, finally obtain the step of 2-d wavelet decomposition coefficient.
Wherein, said step (3) further comprises: the step of DC coefficient coding and the parallel processing of ac coefficient coding in the CCSDS scanning encoding module.
Wherein, said step (3) further comprises:
By first grandson's coefficient, the day after tomorrow subsystem number, last father's coefficient, single pass obtains the ac coefficient degree of depth of 16 " j-trees " to the scanning sequency of coefficient of wavelet decomposition; The escape word of 16 j-trees of parallel computation; Wherein, the memory space buffer memory opened up in addition in the escape word greater than 1 bit; The parallel processing of calculation code option time-division two parts, first accomplishes the reading of the escape word copy of 0～7 j-tree, and second portion is accomplished the step that reads to the escape word copy of 8～15 j-trees.
Wherein, said step (3) further comprises: to 16 j-trees and the line scanning of coefficient of wavelet decomposition; In the process of coding, it is the optimum code option that the code word size that travels through all the encoding options is selected the minimum option of code length, then according to the table look-up step of coding of option.
Wherein, said step (2) and (3) further comprise: the data among wavelet transformation module and the block scan module reuse Dwt_ram; DC coefficient code stream that CCSDS scanning encoding module produces and ac coefficient encoding code stream get into the code stream concatenation module through the alternative selector; The code stream that original image frame header that transmits via inner buffer FIFO1 and code stream concatenation module obtain gets into the step of inner buffer FIFO2 output through the alternative selector; Wherein, said alternative selector is controlled by control module.
Wherein, said step (4) further comprises: the code stream concatenation module is added digit counter in the link of code word splicing and output, if counter has satisfied compression ratio, then stops the step of encoding at once.
The invention has the advantages that:
1, image compression processing system provided by the invention and method compression effectiveness are between JPEG2000 and EZW, and effect is suitable with JPEG2000 when low bit rate compression (compression ratio 8:1 and 16:1).
2, the core design of image compression processing system provided by the invention and method is to carry out computing to small images, adopts the heavy synchronization mechanism of decoding can prevent the error code diffusion in the spatial data transmission, low in energy consumption (≤1watt/Msamples/sec).
3, a large amount of concurrent operations of adopting of image compression processing system provided by the invention and method and the flowing structure processing speed (data processing speed when frequency is 100MHz is 20Mpixels/s) that improved chip can satisfy spaceborne image high power compressing requirement.
4, image compression processing system provided by the invention and method are through test and checking, and systematic function can satisfy the AEROSPACE APPLICATION requirement.Algorithm support based on frame (Frame) input picture form (image that the CCD camera produces) and based on the input picture form of band (Strip) (pushing away the image that the transducer of sweeping type produces); The progressive picture compression be can carry out, near-earth observation and deep layer space exploration task are suitable for.
Description of drawings
Fig. 1 is embodiment of the invention image compression processing system and method CCSDS compression algorithm framework;
Fig. 2 is algorithm general frame figure in embodiment of the invention image compression processing system and the method;
Fig. 3 is a method of partition block diagram in embodiment of the invention image compression processing system and the method;
Fig. 4 is a two-dimensional wavelet transformation framework in the embodiment of the invention image compression processing system;
Fig. 5 is a two-dimentional DWT hardware structure diagram in the embodiment of the invention image compression processing system;
Fig. 6 is a wavelet transformation coefficient positions distribution map in embodiment of the invention image compression processing system and the method;
Fig. 7 is bit-planes inner segment coded sequence in embodiment of the invention image compression processing system and the method;
Fig. 8 sweeps table and coding module structure chart in the embodiment of the invention image compression processing system;
Fig. 9 is a code stream concatenation module structured flowchart in the embodiment of the invention image compression processing system.
Embodiment
The present invention is based on the image compression algorithm that CCSDS122.0-B-1 recommends, and according to the increase of the characteristics novelty of SPACE APPLICATION the image block pattern, the view data of input is divided into the small images of some 32*32 (perhaps 64*64,128*128) through control module; View data behind the piecemeal gets into wavelet transformation module, scanning encoding module and code stream concatenation module and obtains compressed bit stream.Wherein the small echo module is used for input picture is carried out band decomposition reaching the purpose of decorrelation, and the wavelet coefficient of bit-plane coding module after to conversion scans and encode.Be the flowing water between image block and the image block between wavelet transformation module and scanning encoding module, the code stream concatenation module; The scanning encoding module is to carry out flowing water between each bit-planes.DC coefficient coding and the parallel processing of ac coefficient coding in the scanning encoding module.The scanning sequency of block scan inside modules guarantees that by first grandson's coefficient, the day after tomorrow subsystem number, last father's coefficient single pass can obtain the ac coefficient degree of depth of 16 " j-trees "; The escape word of 16 j-trees of parallel computation.Because the escape word of single-bit is not encoded, for reducing the reading times speed-up computation, the present invention opens up the memory space buffer memory in addition to the escape word greater than a bit, is referred to as copy.The option time-division two parts parallel processing of entropy coding module calculation code, first accomplishes the reading of the escape word copy of 0～7 j-tree, and second portion is accomplished reading the escape word copy of 8～15 j-trees.The spaceborne image compression chip compression effectiveness that the present invention realized is between JPEG2000 and EZW, and effect is suitable with JPEG2000 when low bit rate compression (compression ratio 8:1 and 16:1).Because the core design of chip is to carry out computing to small images, adopt the heavy synchronization mechanism of decoding can prevent the error code diffusion in the spatial data transmission, low in energy consumption (≤1watt/Msamples/sec); In addition, the processing speed (data processing speed when frequency is 100MHz is 20Mpixels/s) that a large amount of concurrent operations of adopting and flowing structure have improved chip can satisfy spaceborne image high power compressing requirement.Through test and checking, systematic function can satisfy the AEROSPACE APPLICATION requirement.Algorithm support based on frame (Frame) input picture form (image that the CCD camera produces) and based on the input picture form of band (Strip) (pushing away the image that the transducer of sweeping type produces); The progressive picture compression be can carry out, near-earth observation and deep layer space exploration task are suitable for.
CCSDS122.0-b-1 be issue in 2005 for AEROSPACE APPLICATION formulation Standard of image compression, its low bit rate compression effectiveness is better than JPEG2000, code check is adjustable continuously.Algorithm use a kind of transition coding model of extensive use; CCSDS compression algorithm framework is as shown in Figure 1; Wherein the small echo module is used for input picture is carried out band decomposition reaching the purpose of decorrelation, and the wavelet coefficient of bit-plane coding module after to conversion scans and encode.
The compression algorithm general frame
Figure is as shown in Figure 2 for the compression algorithm general frame, according to algorithm characteristic, with the data input-buffer; Wavelet transformation, bit-plane coding (comprises the piece interscan, the ac coefficient entropy coding; Code word splicing) and output buffers be in turn connected to form level Four flowing water; Be the flowing water between image block and the image block between wavelet transformation module and scanning encoding module, the code stream concatenation module, the scanning encoding module is to carry out flowing water between each bit-planes, and the coordination of flowing water intermodule is accomplished by interface control module.Because DC coefficient coding and ac coefficient coding are independent fully; The inner scanning sequency of block scan module (BlockScan) guarantees that by first grandson's coefficient, the day after tomorrow subsystem number, last father's coefficient single pass can obtain the ac coefficient degree of depth of 16 " j-trees "; The escape word of 16 j-trees of parallel computation.Because the escape word of single-bit is not encoded, for reducing the reading times speed-up computation, the present invention opens up the memory space buffer memory in addition to the escape word greater than a bit, is referred to as copy.The option time-division two parts parallel processing of entropy coding module calculation code, first accomplishes the reading of the escape word copy of 0～7 j-tree, and second portion is accomplished reading the escape word copy of 8～15 j-trees.
Utilize the buffer structure of poll can realize view data is sent into buffer memory continuously, wavelet transformation is when handling current image block, and buffer memory receives the image of next piece simultaneously.Each buffer area can be stored an image block separately at least, when one of them carries out wavelet transformation, imports next piece image to another buffer memory, and after all accomplishing, the buffer memory task function works on successively.So reduce the data buffering time, guaranteed the continuous processing of view data.
Input of 8 bit gray level images and method of partition
The method of partition block diagram is as shown in Figure 3.Getting 512*512 size 8bit gray scale image is experimental subjects, adds synchronous head and figure image width, height, compression multiple; After the headers such as valid data number, send into FIFO1, in a single day FIFO1 is non-NULL, and the spacing wave of its FIFO1 will be put low; In a single day input and output and buffer memory control (IO and Ram ctrl) module receive this signal, at first judge whether to have empty external cache (External Ram), if do not have; With abort operation,, will begin reading of data from FIFO1 if having; And judge synchronous head simultaneously, and unsuccessful if synchronous head reads, then abandon data; Continue the interpretation synchronous head,, then send into by fifo2_se1 signal gating FIFO2 and with the header of synchronous head and image if synchronous head reads success; Then, the subsequent images data are sent in the external cache, external cache is (to comprise 2) more than 2 to have the static ram that can store the piece image capacity.Meanwhile; Whether input and output and buffer memory control module detect external cache constantly has the sign that is filled with piece image, in case detect, then sends the send_ready signal; Notice BPE_Ctrl module has been ready to send; And the send_start signal of wait BPE_Ctrl module, in case receive this signal, then with this image block output.Dividing block size is 32*32 (perhaps 64*64,128*128), because divide block size to fix, so can calculate the piece first address, each pixel in the Row Column traversal piece successively again realizes the individual pixel of gapless continuous output 1024 (perhaps 4096,16384).In the time of output pixel, put high Data_in_en, make the wavelet transformation module receive the data of input.
The wavelet transformation framework
Wavelet transformation is an important component part of compression algorithm, and the present invention has adopted the less foldable structure of a kind of resource occupation (as shown in Figure 4) to realize wavelet transformation.This framework utilizes one-dimensional wavelet transform nuclear, goes successively, rank transformation obtains the 2-d wavelet decomposition coefficient, is characterized in having reused one-dimensional wavelet transform nuclear, saved logical resource on the sheet, through adopting two block caches, alleviated the complexity of addressing.This framework with go simultaneously, specific rate is slower mutually for the rank transformation framework, but the processing speed of wavelet transformation is not the bottleneck of whole compressibility, it is a kind of rational way that sacrifice speed saves that logical resource takies.
9/7 integer wavelet transformation is that the non-linear of 9/7 discrete wavelet approached; The operation that rounds in the decorrelation process has brought non-linear to algorithm; This nonlinear transformation is not real wavelet transform strictly speaking, yet but exists strict inversion to bring the realization lossless compress.The mode of algorithm use symmetric extension is handled the border, and its formula is following:
Input image data x
i, calculate high-pass coefficient D according to (1) formula
j, and then according to formula (2) calculating low-pass coefficients C
jCan be found out by the wavelet arithmetic formula, mainly be plus and minus calculation and division arithmetic, and division mainly is the power divided by 2, in hardware, can realize quick computing through simple right-shift operation, and it realizes that statement is following:
Dj<＝Xdj-SHIFT_RIGHT(Xb+Xc+1，1)-SHIFT_RIGHT(Xb+Xc-Xa-Xd，4)；
Cj<＝Xcj+SHIFT_RIGHT(Da+Db-2，2)；
The hardware circuit of two dimension DWT, as shown in Figure 5.Mainly contain two one-dimensional wavelet transform processes in the hardware structure diagram, line translation Prow and rank transformation Pcol; Two two-port RAMs, buffer memory MemoryA and buffer memory MemoryB have used free IP core, need not external RAM, have not only optimized design, have improved the speed of service, have also shortened the development time; Control unit Ctrl Unit controls the process of whole wavelet transformation: the generation of address signal, the progression of wavelet transformation etc.Datain_P1 and Datain_P2 are original image data; Deposit among the MemoryA at first; IN2n and IN2n+1 are stored in after line translation among the MemoryB for two sub-set data after dividing, and Adr_MB_P1 and Adr_MB_P2 are the address signal of MemoryB; Wavelet coefficient after the line translation is stored among the MemoryA behind rank transformation again; Adr_MA_P1 and Adr_MA_P2 are the address signal of MemoryA, and control signal Sol_Prow, Eol_Prow, Sol_Pcol and Eol_Pcol are used to control BORDER PROCESSING, and the wavelet transformation final result is stored among the MemoryA.
Bit-plane coding
Bit-plane coding is a kind of effective progressively-encode method, helps carrying out flexibly Rate Control, realizes the progression transmission and blocks at random.Bit-plane coding mainly comprises three steps: scanning, escape word entropy coding (hereinafter to be referred as entropy coding) and code stream splicing.The scanning encoding module is to carry out flowing water between each bit-planes.DC coefficient coding and the parallel processing of ac coefficient coding in the scanning encoding module.The scanning sequency of block scan inside modules guarantees that by first grandson's coefficient, the day after tomorrow subsystem number, last father's coefficient single pass can obtain the ac coefficient degree of depth of 16 " j-trees "; The escape word of 16 j-trees of parallel computation.Because the escape word of single-bit is not encoded, for minimizing is read
The number of times speed-up computation, the present invention opens up the memory space buffer memory in addition to the escape word greater than a bit, is referred to as copy.The option time-division two parts parallel processing of entropy coding module calculation code, first accomplishes the reading of the escape word copy of 0～7 j-tree, and second portion is accomplished reading the escape word copy of 8～15 j-trees.
According to the algorithm of CCSDS122.0-B-1, the wavelet coefficient to 9/7 wavelet transformation obtains according to decomposing the back in the corresponding position of each frequency band, forms quad-tree structure, and the wavelet conversion coefficient location map is as shown in Figure 6.By this structure, each member (DC coefficient) of LL3 subband, corresponding j-tree ({ father p
i, son C
i, grandson H
I0, H
I1, H
I2, H
I3, i=1,2,3) totally 63 ac coefficients, form a square that comprises 64 coefficients, as a scanning element.Because continuous zone of the corresponding original image of these 64 coefficients is stronger with the intersubband statistic correlation in the subband, so help through scanning further decorrelation.
Before each block scan, at first carry out preliminary treatment, the coefficient of different frequency bands is carried out weighting.Calculate the ac coefficient degree of depth (ACDepth), then the DC coefficient and the ac coefficient degree of depth are quantized, parallel afterwards DC coefficient coding and the ac coefficient depth coding of carrying out.DC coefficient coding and ac coefficient depth coding carry out the Rice coding according to the method for CCSDS agreement.
Ac coefficient is encoded to comprise by bit-planes and is scanned and entropy coding two parts content.When scanning by bit-planes, earlier with each scanning element according to the putting in order of coefficient among the LL3, Row Column scans one by one.Wherein, Scan method such as CCSDS122.0-B-1 to each piece are said, and the present invention is with 16 continuous scanning elements also line scanning simultaneously, for each bit-planes; The escape word correspondence that scanning forms is sent into dual port RAM in 16 sheets; 16 scanning elements form the content of a section (segment), and entropy coding is carried out in unification, and the coding of each bit-planes is uncorrelated mutually.During coding, at first read 16 scanning results among the ram, come the compute optimal option through the traversal the encoding option of tabling look-up, encode according to this option then, the method for specifically tabling look-up is seen CCSDS122.0-B-1.The ac coefficient coding is according to bit-planes scanning successively from high to low, and the top of bit-planes determined that by the ac coefficient degree of depth entropy coding order in the bit-planes in the section is as shown in Figure 7.
Coding between each bit-planes is mutually independently, but in the process of scanning, the scanning result of following one deck and the scanning result of last layer are closely related, and can form flowing structure between bit-planes.At first, scan module scans by bit-planes, and scanning result is sent into dual port RAM; Coding module can be encoded then, and scan module can carry out the scanning on next plane simultaneously.For improving sweep speed, the present invention sweeps table and coding module structure chart to 16 j-trees and line scanning, and is as shown in Figure 8.In the process of coding, it is the optimum code option that the code word size that travels through all the encoding options is selected the minimum option of code length, then according to the option coding of tabling look-up.The specific coding process of bit-planes b is following:
Stage0: b most important bit during the complement code of coding DC coefficient is expressed.
Stage1: paternal number types encodes
b[P], signs
b[P].
Stage2: coding son coefficient
1)tran
B，
2) tran
D, at tran
B≠ 0 and t
Max(B) ≠-1 under the situation
3) types
b[C
i] and signs
b(C
i) each i there is t
Max(D
i) ≠ 0 ,-1.(i＝0，1，2)。
Stage3: coding grandson coefficient
If tran
B=0 or t
Max(B)=-1, then need not carry out the stage3 coding, otherwise:
1)tran
G，
2)
，
3) types
b[H
Ij] and signs
b[H
Ij]; Each i there is t
Max(G
i) ≠ 0 ,-1; Each j there is t
Max(H
Ij) ≠ 0 ,-1
Stage4: the type of coding value is b the bit value of 2 AC, and as far as each j-tree, the bit strings of output is by types value t
bB bit value of ac coefficient (x)=2 formed by following order:
P
i(i＝0，1，2)，
C
i(i＝0，1，2)，
H
ij(i＝0，1，2；j＝0，1，2，3)；
Annotate: P={p
0, p
1, p
2----father's set in the j-tree
B={D
0, D
1, D
2----j-tree offspring set
D
i={ C
i, G
i----offspring's coefficient of i family in the j-tree
Types
bThe binary word that b the bit value of each coefficient x constitutes among the coefficient sets ψ under [ψ]----bit-planes b is so that t
b(x)=0or1.
Signs
bThe binary word that the sign bit of each coefficient x constitutes among the coefficient sets ψ under [ψ]-----bit-planes b is so that t
b(x)=1.
Tword [Λ]----representes Λ={ λ
0, λ
1, Λ λ
1In types value be 0 or 1 λ
iThe binary word that sequence is formed.
The code word splicing
Output code flow is that unit transmits with 16 word among the present invention, and it is the code stream of unit that the scattered avriable length codes exported of therefore must will encoding is spliced into the word.Code stream concatenation module structure is as shown in Figure 9.With scattered at first intercepting significance bit of code word,,, and new remaining bit is moved to right if form new unit code stream then export with residue code stream splicing; If it is be not enough to form new unit code stream, then together temporary after the splicing as remaining bit.Simultaneously, for the compression ratio to lossy compression method is controlled flexibly, requirement can be blocked code stream at any time, just need add the position counting in the link of code word splicing and output, in case counter has satisfied compression ratio, will stop coding work at once.Do like this and can save unnecessary work, reduce power consumption.
Claims (12)
1. spaceborne image compression processing system of low bit rate, said system comprises:
One control module is used to coordinate the running of image block, wavelet transformation, scanning encoding and code stream concatenation module;
One wavelet transformation module is used for the view data of input is carried out band decomposition, does the processing of decorrelation, obtains the coefficient of wavelet decomposition of this view data, and this coefficient of wavelet decomposition is sent into CCSDS scanning encoding module;
One CCSDS scanning encoding module is used for coefficient of wavelet decomposition is scanned and encodes, and coding is sent into the code stream concatenation module; And
One code stream concatenation module, being used for the coding of importing is spliced into the word is the code stream of unit;
It is characterized in that said control module is divided into view data the small images of 32*32 or 64*64,128*128 earlier, then this small images is sent into the wavelet transformation module;
Said wavelet transformation module adopts foldable structure, utilize two one-dimensional wavelet transforms nuclears successively to the data of input go, rank transformation, finally obtain the 2-d wavelet decomposition coefficient;
DC coefficient coding and the parallel processing of ac coefficient coding in the said CCSDS scanning encoding module.
2. image compression processing system according to claim 1 is characterized in that, said control module is at first through judging the synchronous head and the length and width of image, the frame head information of compression multiple, the position No. that computing block is first; Row through the piece interior pixel is set number and row number are judged the progress that image reads then; Through position No., image first address, ram numbering in the piece, accordingly, export 1024 or 4096,16384 data continuously at last, accomplish blocking process view data to the wavelet transformation module.
3. image compression processing system according to claim 1 is characterized in that, said CCSDS scanning encoding module comprises: block scan module and entropy coding module;
The scanning sequency of said block scan inside modules is by first grandson's coefficient, the day after tomorrow subsystem number, last father's coefficient, and single pass obtains the ac coefficient degree of depth of 16 " j-trees "; The escape word of 16 j-trees of parallel computation; Wherein, the memory space buffer memory opened up in addition in the escape word greater than 1 bit;
Said entropy coding module calculation code option time-division two parts parallel processing, first accomplishes the reading of the escape word copy of 0～7 j-tree, and second portion is accomplished reading the escape word copy of 8～15 j-trees;
Wherein, said escape word copy is for being directed against the memory space of opening up in addition greater than the escape word of 1 bit.
4. image compression processing system according to claim 3 is characterized in that, said block scan module is to 16 j-trees and line scanning; Said entropy coding module is in the process of coding, and it is the optimum code option that the code word size that travels through all the encoding options is selected the minimum option of code length, then according to the option coding of tabling look-up.
5. image compression processing system according to claim 3 is characterized in that, said wavelet transformation module and block scan module reuse buffer memory Dwt_ram; DC coefficient code stream that said scanning encoding module produces and ac coefficient encoding code stream get into the code stream concatenation module through the alternative selector; The code stream that original image frame header that transmits via inner buffer FIFO1 and code stream concatenation module obtain gets into inner buffer FIFO2 output through the alternative selector; Wherein, said alternative selector is controlled by control module.
6. image compression processing system according to claim 1 is characterized in that, said code stream concatenation module is added digit counter in the link of code word splicing and output, if counter has satisfied compression ratio, then stops coding at once.
7. spaceborne image compress processing method of low bit rate may further comprise the steps:
(1) control module is sent view data into the wavelet transformation module by the order ground of original image;
(2) the wavelet transformation module is carried out band decomposition to the view data of input, does the processing of decorrelation, obtains the coefficient of wavelet decomposition of this view data, and this coefficient of wavelet decomposition is sent into CCSDS scanning encoding module;
(3) CCSDS scanning encoding module scans coefficient of wavelet decomposition and encodes, and coding is sent into the code stream concatenation module;
(4) to be spliced into the word be the code stream of unit to the coding that will import of code stream concatenation module;
It is characterized in that said control module is divided into view data the small images of 32*32 or 64*64,128*128 earlier, then this small images is sent into the wavelet transformation module and carries out wavelet transformation;
Said step (2) further comprises: the wavelet transformation module adopts foldable structure, utilize two one-dimensional wavelet transforms nuclears successively to the data of input go, rank transformation, finally obtain the step of 2-d wavelet decomposition coefficient;
The step of DC coefficient coding and the parallel processing of ac coefficient coding in the said CCSDS scanning encoding module.
8. image compress processing method according to claim 7 is characterized in that, said step (1) further comprises: control module is at first through judging the synchronous head and the length and width of image, the frame head information of compression multiple, the position No. that computing block is first; Row through the piece interior pixel is set number and row number are judged the progress that image reads then; Through position No., image first address, ram numbering in the piece, export the step of 1024,4096 or 16384 data continuously at last to the wavelet transformation module.
9. image compress processing method according to claim 7; It is characterized in that; Said step (3) further comprises: by first grandson's coefficient, the day after tomorrow subsystem number, last father's coefficient, single pass obtains the ac coefficient degree of depth of 16 " j-trees " to the scanning sequency of coefficient of wavelet decomposition; The escape word of 16 j-trees of parallel computation; Wherein, the memory space buffer memory opened up in addition in the escape word greater than 1 bit; The parallel processing of calculation code option time-division two parts, first accomplishes the reading of the escape word copy of 0～7 j-tree, and second portion is accomplished the step that reads to the escape word copy of 8～15 j-trees; Wherein, said escape word copy is for being directed against the memory space of opening up in addition greater than the escape word of 1 bit.
10. image compress processing method according to claim 9 is characterized in that, said step (3) further comprises: to 16 j-trees and the line scanning of coefficient of wavelet decomposition; In the process of coding, it is the optimum code option that the code word size that travels through all the encoding options is selected the minimum option of code length, then according to the table look-up step of coding of option.
11. image compress processing method according to claim 9 is characterized in that, said step (2) and (3) further comprise: the data among wavelet transformation module and the block scan module reuse buffer memory Dwt_ram; DC coefficient code stream that CCSDS scanning encoding module produces and ac coefficient encoding code stream get into the code stream concatenation module through the alternative selector; The code stream that original image frame header that transmits via inner buffer FIFO1 and code stream concatenation module obtain gets into the step of inner buffer FIFO2 output through the alternative selector; Wherein, said alternative selector is controlled by control module.
12. image compress processing method according to claim 7; It is characterized in that; Said step (4) further comprises: the code stream concatenation module is added digit counter in the link of code word splicing and output, if counter has satisfied compression ratio, then stops the step of encoding at once.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200810226721 CN101742300B (en) | 2008-11-21 | 2008-11-21 | System and method for compressing satellite images with low bit rate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200810226721 CN101742300B (en) | 2008-11-21 | 2008-11-21 | System and method for compressing satellite images with low bit rate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101742300A CN101742300A (en) | 2010-06-16 |
| CN101742300B true CN101742300B (en) | 2012-05-09 |
Family
ID=42465079
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200810226721 Expired - Fee Related CN101742300B (en) | 2008-11-21 | 2008-11-21 | System and method for compressing satellite images with low bit rate |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101742300B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101931809B (en) * | 2010-07-29 | 2012-05-09 | 西安空间无线电技术研究所 | Spacecraft image decomposition and transmission method |
| FI4002842T3 (en) | 2012-06-26 | 2023-11-02 | Lg Electronics Inc | Video decoding method, video encoding method and storage medium storing encoded video information |
| CN103108185B (en) * | 2013-01-31 | 2015-09-02 | 西安电子科技大学 | Meet bit-plane coding hardware configuration and the method for CCSDS standard |
| CN103179396A (en) * | 2013-03-04 | 2013-06-26 | 中国科学院长春光学精密机械与物理研究所 | System and method for controlling CCSDS (consultative committee for space data system) image compressing code in spatial TDICCD (time delayed integration charge coupled device) camera application |
| CN104486640B (en) * | 2014-12-30 | 2017-06-20 | 华中科技大学 | The message sink coding of a kind of anti-error code and packet loss and intelligent coding/decoding method |
| CN107483850B (en) * | 2017-08-11 | 2019-12-17 | 西安电子科技大学 | low-delay high-definition digital image transmission method |
| CN109788298A (en) * | 2019-02-01 | 2019-05-21 | 中国科学院电子学研究所 | Method for compressing image based on FPGA |
| CN111432189B (en) * | 2020-05-07 | 2022-03-11 | 上海航天计算机技术研究所 | Satellite-borne multi-channel image compression and detection integrated device and use method |
| CN112437309A (en) * | 2020-11-12 | 2021-03-02 | 北京深维科技有限公司 | JPEG encoding method and device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6178470B1 (en) * | 1996-10-30 | 2001-01-23 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Chip for CCSDS compatible serial data streams |
| CN1460969A (en) * | 2003-06-30 | 2003-12-10 | 大唐微电子技术有限公司 | Hierarchy tree set partition image coding decoding method based of digital signal processor |
-
2008
- 2008-11-21 CN CN 200810226721 patent/CN101742300B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6178470B1 (en) * | 1996-10-30 | 2001-01-23 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Chip for CCSDS compatible serial data streams |
| CN1460969A (en) * | 2003-06-30 | 2003-12-10 | 大唐微电子技术有限公司 | Hierarchy tree set partition image coding decoding method based of digital signal processor |
Non-Patent Citations (6)
| Title |
|---|
| 吴斌 |
| 孔令波 |
| 孔令波;吴斌;陈瑞清;殷福亮.CCSDS图像数据压缩算法的FPGA实现.<<中国宇航学会深空探测技术专业委员会第三届学术会议论文集>>.2006,182-189. * |
| 殷福亮.CCSDS图像数据压缩算法的FPGA实现.<<中国宇航学会深空探测技术专业委员会第三届学术会议论文集>>.2006,182-189. |
| 陈瑞清 |
| 雷震霖.空间图像CCSDS压缩算法研究与FPGA实现.<<中国优秀硕士学位论文全文数据库>>.2008, * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101742300A (en) | 2010-06-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101742300B (en) | System and method for compressing satellite images with low bit rate | |
| CN101404772B (en) | VLSI image compression encoder based on wavelet transformation | |
| CN101771874A (en) | Satellite image compression method and device for realizing satellite image compression | |
| CN102186076B (en) | Image compression method and image compression device for real-time code rate pre-allocation | |
| US9510008B2 (en) | Video decoder memory bandwidth compression | |
| CN102833546B (en) | High-speed image compression method and device based on wavelet sub-band interleaving optimal quantization | |
| CN101841713B (en) | Video coding method for reducing coding code rate and system | |
| CN101252694A (en) | Address mapping system and frame storage compression of video frequency decoding based on blocks | |
| CN101867809A (en) | High-speed image compression VLSI (very Large Scale integration) encoding method and encoder based on pulse array | |
| CN101267558A (en) | Low storage coder based on code block in JPEG2000 standard and its coding method | |
| CN1725858A (en) | The equipment and the method that are used for the control bit rate | |
| Corsonello et al. | Low bit rate image compression core for onboard space applications | |
| CN112866695B (en) | Video encoder | |
| Huang et al. | Low memory and low complexity VLSI implementation of JPEG2000 codec | |
| CN102547291A (en) | Field programmable gate array (FPGA)-based joint photographic experts group (JPEG) 2000 image decoding device and method | |
| CN102256126A (en) | Method for coding mixed image | |
| CN102333222A (en) | Two-dimensional discrete wavelet transform circuit and image compression method using same | |
| CN101754014B (en) | Information processing apparatus and method | |
| KR102247196B1 (en) | Vc-2 decoding using parallel decoding paths | |
| CN103379349A (en) | Viewpoint composite predictive encoding method, decoding method, corresponding devices and code stream | |
| CN111316645A (en) | Encoder, encoding system and encoding method | |
| Wang et al. | High speed and bi-mode image compression core for onboard space application | |
| Ye et al. | Memory-efficient image codec using line-based backward coding of wavelet trees | |
| EP1652146B1 (en) | Implementation of the jpeg2000 compression algorithm in hardware | |
| Ortega et al. | Implementations of the discrete wavelet transform: complexity, memory, and parallelization issues |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120509 Termination date: 20181121 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |