CN107888922A - The image pre-processing method and device overflowed for the anti-code stream of JPEG LS lossless compression algorithms - Google Patents
The image pre-processing method and device overflowed for the anti-code stream of JPEG LS lossless compression algorithms Download PDFInfo
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Abstract
The invention discloses a kind of image pre-processing method and device overflowed for the anti-code stream of JPEG LS lossless compression algorithms.Wherein, this method comprises the following steps：Partiting step, judgment step, image preprocessing step, the first lossless compression-encoding step and the second lossless compression-encoding step.The present invention is not only able to preferably solve the code stream overflow problem that JPEG LS lossless compression algorithms are likely to occur in application, and can also retain the relative independentability of JPEG LS lossless compression-encoding modules, is easy to modularized design.
Description
Technical field
The invention belongs to digital image compression field, more particularly to one kind to be used for the anti-code stream of JPEG-LS lossless compression algorithms
The image pre-processing method and device of spilling.
Background technology
As the development and user of satellite remote sensing imaging technique are to ground resolution and the continuous improvement of breadth requirement, remote sensing
The image resolution ratio more and more higher that satellite obtains, to be stored and transmission image data amount is thus caused to sharply increase, to real-time
Data transmission system brings huge pressure, in order to solve the lance between magnanimity high speed data transfer and limited transmission bandwidth
Shield, it is necessary to using data compression technique.Data compression technique is broadly divided into two major classes on current star, Lossless Compression and damages pressure
Contracting.Lossless Compression is that the image after compression is encoded, the view data before can accurately being compressed.Lossless Compression carries
Supply not lose the compress technique of information, be based primarily upon information entropy principle and encoded, it is currently used to have predictive coding, conversion
Coding and hybrid coding etc..Lossless Compression can inerrably recover original image from compressed data, but compression ratio is not high, generally
2:1~5:1.In recent years due to increasingly raising of the user to image quality requirements, domsat employs of good performance successively
Lossless data compression algorithms JPEG-LS, such as ZY-3, KZ-1 satellite.But in certain circumstances, satellite remote sensing system
Data can still can exceed that the upper limit of channel capacity even with JPEG-LS Lossless Compressions, and the phenomenon that code stream overflows occurs, at this moment by
In the loss of bit stream data follow-up view data will be caused not solve, image information is lost, and it is follow-up right to have had a strong impact on
The parsing work of satellite data.Therefore, a kind of method of image procossing is studied to solve the code stream of JPEG-LS Lossless Compressions spilling
Problem has very important realistic meaning.
Code stream overflow problem is not strange in compression of images field, still, the controllable Coding Compression Algorithm of former code check,
If the compression algorithms such as JPEG2000, CCSDS, SPITE are when occurring code stream and overflowing, the detailed information of image can be only lost, but not
The main information of image is lost, the parsing work to subsequent satellites data will not cause to have a strong impact on.And JPEG-LS Lossless Compressions
Algorithm is a kind of quality controllable Coding Compression Algorithm, and code check is uncontrollable, the Progressive transmission of code stream is not supported, in practical application
When, once code stream spillover occurs, since the position that code stream overflows, follow-up image information can all lose, in vision
On can show as reconstruction image end there is the image bad block of default Pixel Information, have a strong impact on subsequently to satellite remote sensing images
Interpretation.At present because JPEG-LS lossless compression algorithms do not widely use on satellite remote sensing system, and code stream spillover
Only it can just occur under indivedual specified conditions, therefore the research of the anti-code stream overflow problem on JPEG-LS lossless compression-encodings
The concern about designer is not obtained also, related Research Literature is also very few.
The content of the invention
Present invention solves the technical problem that it is：Overcome the deficiencies in the prior art, there is provided one kind is used for the lossless pressures of JPEG-LS
The image pre-processing method and device that the anti-code stream of compression algorithm overflows, are not only able to preferably solve JPEG-LS lossless compression algorithms
The code stream overflow problem being likely to occur in application, and the relatively independent of JPEG-LS lossless compression-encoding modules can also be retained
Property, it is easy to modularized design.
The object of the invention is achieved by the following technical programs：According to an aspect of the invention, there is provided a kind of use
In the image pre-processing method that the anti-code stream of JPEG-LS lossless compression algorithms overflows, the described method comprises the following steps：Division step
Suddenly：If image is divided to obtain individual subgraph；Judgment step：Judge whether the value of image pre-processing module transformation parameter is more than
1；Image preprocessing step：If the value of image pre-processing module transformation parameter is more than 1, image preprocessing is carried out to each subgraph,
Image after being converted accordingly；First lossless compression-encoding step：Lossless pressure is carried out according to this to the image after each conversion
Contracting handles and judges whether the code stream of the image after the conversion corresponding to current subgraph has spilling situation, if there is spilling situation,
The transformation parameter of image after conversion corresponding to current subgraph is adjusted；Second lossless compression-encoding step：If image
The value of pretreatment module transformation parameter is equal to 1, carries out Lossless Compression processing according to this to each subgraph and judges the code of current subgraph
Whether stream has spilling situation, if there is spilling situation, the transformation parameter corresponding to current subgraph is adjusted.
In the above-mentioned image pre-processing method overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, in the division step
In rapid, subgraph divides size by the breadth of camera input image, the storage disposal ability of compressed encoding hardware components, and uses
Compression algorithm factor determine.
It is pre- in described image in the above-mentioned image pre-processing method overflowed for the anti-code stream of JPEG-LS lossless compression algorithms
In processing step, the formula of image preprocessing is as follows：In formula, f (i, j) is subgraph, and g (i, j) is change
Image after changing, α are transformation parameter, α>1,For lower floor operation, i is the line number of image picture elements, and j is the row of image picture elements
Number.
In the above-mentioned image pre-processing method overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, the first Lossless Compression
Coding step specifically includes：Carry out Lossless Compression processing according to this to the image after each conversion and to the image after current conversion
Acquired transformation parameter carries out interpretation：If the transformation parameter acquired by image after current conversion is 1, statistics is current total
Output squeezing code flow, and compared with default compressed code flow, if current total output squeezing code flow is more than in advance
If compressed code flow, the transformation parameter acquired by the image after current conversion is adjusted；If after current conversion
Transformation parameter acquired by image is more than 1, counts current total output squeezing code flow, and obtain the total compressed code of a subgraph
Difference between flow and current total output squeezing code flow, then judges whether difference is more than first threshold, if difference
Transformation parameter α acquired by whether being more than the image after first threshold and conversion corresponding to a upper subgraph is equal to current subgraph institute
The transformation parameter that image after corresponding conversion is taken, then stop image preprocessing.
In the above-mentioned image pre-processing method overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, the second Lossless Compression
Coding step specifically includes：If the value of image pre-processing module transformation parameter is equal to 1, Lossless Compression is carried out according to this to each subgraph
Handle and interpretation is carried out to the transformation parameter acquired by current subgraph：If the transformation parameter acquired by current subgraph is equal to 1,
The current total output squeezing code flow of statistics, and compared with default compressed code flow, if current total output squeezing
Code flow is more than default compressed code flow, and the transformation parameter acquired by current subgraph is adjusted；If current subgraph is taken
Transformation parameter be more than 1, the current total output squeezing code flow of statistics, and obtain the total compressed code flow of a subgraph with ought
Difference between preceding total output squeezing code flow, then judges whether difference is more than Second Threshold, if difference is more than second
Transformation parameter acquired by threshold value and a upper subgraph is equal to the transformation parameter that current subgraph is taken, then stops image preprocessing.
In the above-mentioned image pre-processing method overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, the public affairs of first threshold
Formula is as follows：
T=λ * IQ
Wherein, λ is scale factor, 0<λ<1, IQ is the total size of input subgraph.
In the above-mentioned image pre-processing method overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, the public affairs of Second Threshold
Formula is as follows：
T'=λ ' * IQ
Wherein, λ ' is scale factor, 0<λ<1, IQ is the total size of input subgraph.
In the above-mentioned image pre-processing method overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, in first nothing
Damage in compressed encoding step, the transformation parameter of the image after conversion corresponding to current subgraph is adjusted as 2.
In the above-mentioned image pre-processing method overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, in second nothing
Damage in compressed encoding step, the transformation parameter corresponding to current subgraph is adjusted as 2.
According to another aspect of the present invention, a kind of anti-code stream of JPEG-LS lossless compression algorithms that is used for is additionally provided to overflow
Image preprocess apparatus, described device includes：Division module, if for being divided to obtain individual subgraph to image；Image is pre-
Processing module, for judging whether the value of image pre-processing module transformation parameter is more than 1；And if it is used for image pre-processing module
The value of transformation parameter is more than 1, and image preprocessing, the image after being converted accordingly are carried out to each subgraph；Lossless Compression is compiled
Code module, for after carrying out Lossless Compression processing according to this to the image after each conversion and judging the conversion corresponding to current subgraph
The code stream of image whether have spilling situation, if there is spilling situation, the change to the image after the conversion corresponding to current subgraph
Parameter is changed to be adjusted；And if it is equal to 1 for the value of image pre-processing module transformation parameter, nothing is carried out according to this to each subgraph
Damage compression handles and judges whether the code stream of current subgraph has spilling situation, if having spilling situation, to corresponding to current subgraph
Transformation parameter be adjusted.
The present invention has the advantages that compared with prior art：
(1) problem solved by the invention compensate for what JPEG-LS lossless compression algorithms were likely to occur in actual applications
Defect, laid a good foundation for the follow-up algorithm widely using for remote sensing system on star.
(2) open function to image pre-processing module is not only devised in the present invention, and have also been devised image and locate in advance
The closing function of module is managed, can not only carry out the processing of problem in time when code stream spillover occurs, and in exhausted big portion
In the case of sub-bit stream is normal, the handling process that original image carries out JPEG-LS compressed encodings is not intervened, is retained to greatest extent
The information of original image.
(3) image pre-processing method designed in the present invention, it is to solve problem from the angle of image procossing, remains follow-up
The relative independentability of JPEG-LS compressed encoding modules, therefore be convenient for modularized design, be advantageous to carry out quick function embedding
Enter and remove, and be adapted to all compressing and coding systems using JPEG-LS lossless compression algorithms.
(4) what is used in the present invention enters the operation method of line translation to input original subpicture, and it is real to have taken into account follow-up hardware
Existing transition problem, thus when conversion progress hardware is realized, it is convenient and simple, it is easy to accomplish, avoid cumbersome floating-point fortune
Calculate.
(5) control signal of the JPEG-LS lossless compression-encoding module feedbacks used in the present invention, what is utilized is compression
Some values of information commonly used in coded system, design is not only easy and effective, and when progress FPGA is realized, does not increase substantially
The resource utilization of original compressing and coding system.
Brief description of the drawings
By reading the detailed description of hereafter preferred embodiment, it is various other the advantages of and benefit it is common for this area
Technical staff will be clear understanding.Accompanying drawing is only used for showing the purpose of preferred embodiment, and is not considered as to the present invention
Limitation.And in whole accompanying drawing, identical part is denoted by the same reference numerals.In the accompanying drawings：
Fig. 1 is the algorithm block diagram of image pre-processing module provided in an embodiment of the present invention；
The anti-code stream of a JPEG-LS lossless compression-encoding that Fig. 2 is the application present invention provided in an embodiment of the present invention overflows
Realize block diagram；
Fig. 3 is that the hardware of image pre-processing module provided in an embodiment of the present invention realizes the schematic diagram of port definition；
Fig. 4 (a) is the schematic diagram of original input picture provided in an embodiment of the present invention；
Fig. 4 (b) is the schematic diagram that code stream provided in an embodiment of the present invention overflows reconstruction image；
Fig. 4 (c) is the schematic diagram of reconstruction image after image preprocessing provided in an embodiment of the present invention；
Fig. 5 is the control flow chart of image pre-processing module provided in an embodiment of the present invention.
Embodiment
The exemplary embodiment of the disclosure is more fully described below with reference to accompanying drawings.Although the disclosure is shown in accompanying drawing
Exemplary embodiment, it being understood, however, that may be realized in various forms the disclosure without should be by embodiments set forth here
Limited.On the contrary, these embodiments are provided to facilitate a more thoroughly understanding of the present invention, and can be by the scope of the present disclosure
Completely it is communicated to those skilled in the art.It should be noted that in the case where not conflicting, embodiment in the present invention and
Feature in embodiment can be mutually combined.Describe the present invention in detail below with reference to the accompanying drawings and in conjunction with the embodiments.
A kind of image pre-processing method overflowed for the anti-code stream of JPEG-LS lossless compression algorithms is present embodiments provided,
Step is as follows：
(1) in addition to the breadth of image is determined by the parameter of CCD camera, input picture is the remote sensing images of camera input
There is no height limitation, after typically carrying out subgraph division, then input to follow-up unit and handled, this partly belongs to this
Category known in art personnel, is repeated no more here.Therefore the input picture for giving image pre-processing module is ready-portioned
Subgraph, image mentioned herein refer both to the input subgraph.
(2) image pre-processing module first has to judge transformation parameter alfa, transformation parameter when being handled
Alfa initial value is that 1, alfa value has also indicated that the opening and closing state of image pre-processing module simultaneously, works as alfa=1
When show that image pre-processing module is closed, during closed mode, image pre-processing module does not do any to input subgraph
Conversion, the JPEG-LS lossless compression-encodings module being directly fed to below complete Lossless Compression processing；Work as alfa>Show image when 1
Pretreatment module is in opening, and at this moment image pre-processing module will enter line translation to input subgraph, and by the son after conversion
The JPEG-LS lossless compression-encodings module that figure is given below completes Lossless Compression processing；
(3) JPEG-LS lossless compression-encodings module, also will be to current after being compressed and having encoded to current subgraph
Alfa values carry out interpretation：As alfa=1, (4) step is gone to；Work as alfa>When 1, (5) step is gone to；
(4) as alfa=1, JPEG-LS lossless compression-encodings module counts current total output squeezing code flow first
SQ (i), and compared with the compressed code flow OSQ with requiring (not less than 1.3 times compressions), if SQ (i)>OSQ, then put code stream
Overflow control signal overflow_ctrl<=' 1 ', i.e., high level is effective；Otherwise, then code stream overflow control signal is put
overflow_ctrl<=' 0 ', i.e., low level is invalid；
Meanwhile image pre-processing module detects the code stream overflow control signal overflow_ctrl of feedback in real time, works as discovery
When its is effective, the adjustment to transformation parameter alfa is completed, alfa is exactly adjusted to alfa=2 by a specific embodiment,
Can be seen that alfa=2 from the simulation result of above 8 width remote sensing images can be original by the reduced dynamic range of original input picture
The half come, image its compression performance after conversion are obtained for different degrees of raising, can substantially meet channel capacity
Required compression ratio, moreover, the conversion of the image preprocessing can be converted into right-shift operation in hardware realization, realize
Get up very simple, i.e.,：
G (i, j)=f (i, j)>>1
(5) alfa is worked as>When 1, JPEG-LS lossless compression-encodings module equally first counts current total output squeezing code flow
SQ (i), and obtain differences of the total compressed code flow SQ (i-1) of a subgraph between SQ (i), i.e.,：
Δ SQ=SQ (i-1)-SQ (i)
Then judging whether Δ SQ is more than threshold value T, a specific embodiment is exactly to take T=0.2*IQ, wherein, IQ is
It is originally inputted the total size (byte number) of subgraph.The size of each subgraph is equal, and total size here refers to subgraph
Input total amount of data, can be in units of byte.
If Δ SQ>Alfa values α (i-1) is equal to the alfa value a (i) that current subgraph is taken acquired by T and a upper subgraph, then
JPEG-LS lossless compression-encoding modules put code stream normal control signal initial_ctrl<=' 1 ', i.e., high level is effective, no
Then, then code stream normal control signal initial_ctrl is put<=' 0 ', i.e., low level is invalid；
Meanwhile image pre-processing module detects the code stream normal control signal initial_ctrl of feedback in real time, works as discovery
When its is effective, the parameter alfa of image pre-processing module is reinitialized to 1, i.e., image pre-processing module, which is in, closes shape
State；Otherwise, holding parameter alfa value is constant, and image pre-processing module is kept it turned on.
Illustrate the figure overflowed for the anti-code stream of JPEG-LS lossless compression algorithms below in conjunction with accompanying drawing and specific implementation example
As the specific implementation of preprocess method：
Table 1 is different source images using compression ratio during JPEG-LS progress Lossless Compressions, this 8 width image of selection
It is more representational 10 bit remote sensing images, image size is 2048*2048, and NEAR takes fixed value 0, picture material
It is related to mountain range, city, ocean, harbour etc..
The different images content of table 1 carries out the compression ratio of Lossless Compression using JPEG-LS
Different input original images is can be seen that from this table, when NEAR values all take zero, i.e., all realizes the lossless pressure of artwork
During contracting, the code check of output is of different sizes, that is to say, that code check is uncontrollable.To find out its cause, the core algorithm used with JPEG-LS
LOCO-I coding principle is relevant with flow, and JPEG-LS lossless compression algorithms are a kind of quality controlled compression algorithms, are being rebuild
While quality can obtain accurate control, another cost for bringing be exactly compression bit rate of its output be it is uncontrollable,
JPEG-LS lossless compression algorithms why the compression efficiency that can be got well, and be widely used in lossless data compression, be on the one hand
Because employing adaptive prediction, context modeling reaches the mesh for reducing image entropy to remove the correlation between image pixel
, on the other hand it is then to reduce the amount of storage of code stream, to reach entropy reason by using brigade commander's coding and adaptive classification coding
The limit of opinion.It can therefore be seen that different picture materials, the compression performance of JPEG-LS lossless compression algorithms is determined, when defeated
Enter that the correlation of image is stronger, and redundancy is bigger, when the flat region of image is more, the compression effect of JPEG-LS lossless compression algorithms
Rate is higher, and the code check of output is smaller, otherwise when the correlation of input picture is smaller, redundancy is got over hour, and the flat region of image is got over
When few, the compression efficiency of JPEG-LS lossless compression algorithms is lower, and the code check of output is bigger.
The present embodiment additionally provides a kind of image preprocessing dress overflowed for the anti-code stream of JPEG-LS lossless compression algorithms
Put, the device includes：Division module, image pre-processing module and lossless compression-encoding module.Wherein, division module, for pair
If image is divided to obtain individual subgraph.Image pre-processing module, for judging that the value of image pre-processing module transformation parameter is
It is no to be more than 1；If the value for being additionally operable to image pre-processing module transformation parameter is more than 1, image preprocessing is carried out to each subgraph, obtained
Image after corresponding conversion.Lossless compression-encoding module, for being carried out according to this at Lossless Compression to the image after each conversion
Manage and judge whether the code stream of the image after the conversion corresponding to current subgraph has spilling situation, if there is spilling situation, to working as
The transformation parameter of the image after conversion corresponding to preceding subgraph is adjusted；And if it is used for image pre-processing module transformation parameter
Value be equal to 1, carry out Lossless Compression processing according to this to each subgraph and judge whether the code stream of current subgraph has spilling situation, if
There is spilling situation, then the transformation parameter corresponding to current subgraph is adjusted.
Fig. 2 is to realize block diagram using what the anti-code stream of a JPEG-LS lossless compression-encoding of the present invention overflowed, with reference to
The block diagram, by taking the JPEG-LS lossless compression-encodings that the bit image of remote sensing 10 is carried out not less than 1.3 times as an example, image is discussed in detail
The specific implementation of pretreatment module.
First, the handling process of image pre-processing module
If the image being originally inputted is f (i, j), g (i, j) is processing image after image preprocessing, its algorithm frame
Figure is as shown in Figure 1.
The process that image preprocessing is carried out to original input picture f (i, j) is to complete following conversion：
In formula, α is Dynamic gene, α>1,For lower floor operation.
We take α=1.5 and 2 two kinds of values respectively below, and above-mentioned 8 representative remote sensing images are located in advance
The situation of change of reason, the then compression performance of the front and rear image completion JPEG-LS lossless compression-encodings of contrast images pretreatment：
Compression performance contrasts before and after the image preprocessing of table 2
Dynamic range contrasts before and after the image preprocessing of table 3
As can be seen from the above table, after being pre-processed respectively to original image, image completes JPEG-LS Lossless Compressions
Compression ratio be improved, and when α it is bigger, the compression ratio of Lossless Compression is higher, from the angle of information theory it is recognised that this is exactly
Because after image preprocessing, reducing the categorical measure (as shown in table 3) of information word, effectively reducing image entropy, so that
The compression performance for obtaining compression algorithm is improved, and the compressed code flow of output greatly reduces, so as to solve code stream spilling
Problem.
2nd, the control flow of image pre-processing module
Image pre-processing module is mainly to complete to enter line translation to the pixel value for inputting subgraph, and by the pixel value after conversion
Give follow-up compressed encoding module and carry out JPEG-LS Lossless Compressions, meanwhile, JPEG-LS lossless compression-encodings module is by working as
The compression performance (compression ratio) of preceding subgraph produces code stream overflow control signal overflow_ctrl and code stream normal control signal
Initial_ctrl, to adjust the transformation parameter alfa of image pre-processing module in real time, complete the unlatching of image pre-processing module
And closing.
Fig. 3 is port definition when image pre-processing module is realized with FPGA, wherein, datain is current input subgraph
Pixel value, synin are input data datain synchronizing signal, and overflow_ctrl is JPEG_LS compressed encoding module feedbacks
Code stream overflow control signal, initial_ctrl be JPEG-LS compressed encoding module feedbacks code stream normal control signal,
Dataout is the pixel value entered to datain after line translation of image pre-processing module output, and synout is data dataout's
Synchronizing signal, alfa are currently employed parameter a (i).
Fig. 4 uses the image pre-processing method of the above, and anti-code stream is carried out to the 10 bit remote sensing images of a width 1024*1024
The result of Overflow handling, original camera input picture are Fig. 4 (a), when the image is done directly JPEG-LS lossless compression-encodings its
Compression ratio is 1.2036 times, passes the 1.3 times of compressions of required channel capacity down in real time less than satellite, therefore code stream occur and overflow now
As the code stream beyond part can not reach ground down, therefore cause occur image bad block in the reconstruction image of ground, such as Fig. 4 (b) institutes
Show, original input picture is subjected to image preprocessing and then carries out JPEG-LS compressed encodings, image compression rate can improve
To 1.3731 times, fully meet satellite and pass the 1.3 times of compressions of required channel capacity, the compressed bit stream of image after processing down in real time
It is able to completely be passed down, reconstruction image completely without bad block, as shown in Fig. 4 (c), unlike original input picture, is schemed
Reconstruction image brightness after picture pretreatment decreases, and this is just because of the changing image dynamic range contracting after image preprocessing
The small half for original image, but picture material reservation is perfect, does not influence ground interpretation.
The image that the embodiment of the present invention is overflowed with the anti-code stream of remote sensing images JPEG-LS lossless compression algorithms is pre-
Exemplified by processing method, but the use range of the present invention is not limited to remote sensing images field.
Embodiment described above is the present invention more preferably embodiment, and those skilled in the art is in this hair
The usual variations and alternatives carried out in the range of bright technical scheme should all include within the scope of the present invention.
Claims (10)
- A kind of 1. image pre-processing method overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, it is characterised in that the side Method comprises the following steps：Partiting step：If image is divided to obtain individual subgraph；Judgment step：Judge whether the value of image pre-processing module transformation parameter is more than 1；Image preprocessing step：If the value of image pre-processing module transformation parameter is more than 1, image is carried out to each subgraph and located in advance Reason, the image after being converted accordingly；First lossless compression-encoding step：Carry out Lossless Compression processing according to this to the image after each conversion and judge current subgraph Whether the code stream of the image after corresponding conversion has spilling situation, if there is spilling situation, to the change corresponding to current subgraph The transformation parameter of image after changing is adjusted；Second lossless compression-encoding step：If the value of image pre-processing module transformation parameter is equal to 1, each subgraph is carried out according to this Lossless Compression handles and judges whether the code stream of current subgraph has spilling situation, if there is spilling situation, to current subgraph, institute is right The transformation parameter answered is adjusted.
- 2. the image pre-processing method according to claim 1 overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, its It is characterised by：In the partiting step, subgraph divides size by the breadth of camera input image, compressed encoding hardware components Disposal ability is stored, and the compression algorithm factor used determines.
- 3. the image pre-processing method according to claim 1 overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, its It is characterised by：In described image pre-treatment step, the formula of image preprocessing is as follows：In formula, f (i, j) is subgraph, and g (i, j) is the image after conversion, and α is transformation parameter, α>1,For lower floor operation, i is The line number of image picture elements, j are the row number of image picture elements.
- 4. the image pre-processing method according to claim 1 overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, its It is characterised by：First lossless compression-encoding step specifically includes：Lossless Compression processing is carried out according to this to the image after each conversion And interpretation is carried out to the transformation parameter acquired by the image after current conversion：If the change acquired by image after current conversion It is 1 to change parameter, the current total output squeezing code flow of statistics, and compared with default compressed code flow, if current total Output squeezing code flow be more than default compressed code flow, to acquired by the image after current conversion transformation parameter carry out Adjustment；If the transformation parameter acquired by image after current conversion is more than 1, current total output squeezing code flow is counted, and The difference between the total compressed code flow of a subgraph and current total output squeezing code flow is obtained, then whether judges difference More than first threshold, become if whether difference is acquired more than the image after the conversion corresponding to first threshold and a upper subgraph Parameter alpha is changed equal to the transformation parameter that the image after the conversion corresponding to current subgraph is taken, then stops image preprocessing.
- 5. the image pre-processing method according to claim 1 overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, its It is characterised by：Second lossless compression-encoding step specifically includes：If the value of image pre-processing module transformation parameter is equal to 1, to every Individual subgraph carries out Lossless Compression processing and carries out interpretation to the transformation parameter acquired by current subgraph according to this：If current subgraph Acquired transformation parameter is equal to 1, counts current total output squeezing code flow, and compared with default compressed code flow Compared with if current total output squeezing code flow is more than default compressed code flow, to the transformation parameter acquired by current subgraph It is adjusted；If the transformation parameter acquired by current subgraph is more than 1, current total output squeezing code flow is counted, and obtain Difference between the total compressed code flow of one subgraph and current total output squeezing code flow, then judge difference whether more than the Two threshold values, if difference is more than transformation parameter acquired by Second Threshold and a upper subgraph and is equal to the conversion ginseng that current subgraph is taken Number, then stop image preprocessing.
- 6. the image pre-processing method according to claim 4 overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, its It is characterised by：The formula of first threshold is as follows：T=λ * IQWherein, λ is scale factor, 0<λ<1, IQ is the total size of input subgraph.
- 7. the image pre-processing method according to claim 5 overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, its It is characterised by：The formula of Second Threshold is as follows：T'=λ ' * IQWherein, λ ' is scale factor, 0<λ<1, IQ is the total size of input subgraph.
- 8. the image pre-processing method according to claim 1 overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, its It is characterised by：In the first lossless compression-encoding step, the transformation parameter of the image after conversion corresponding to current subgraph It is adjusted as 2.
- 9. the image pre-processing method according to claim 1 overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, its It is characterised by：In the second lossless compression-encoding step, the transformation parameter corresponding to current subgraph is adjusted as 2.
- 10. a kind of image preprocess apparatus overflowed for the anti-code stream of JPEG-LS lossless compression algorithms, it is characterised in that described Device includes：Division module, if for being divided to obtain individual subgraph to image；Image pre-processing module, for judging whether the value of image pre-processing module transformation parameter is more than 1；And if it is used for image The value of pretreatment module transformation parameter is more than 1, and image preprocessing, the image after being converted accordingly are carried out to each subgraph；Lossless compression-encoding module, for carrying out Lossless Compression processing according to this to the image after each conversion and judging current subgraph Whether the code stream of the image after corresponding conversion has spilling situation, if there is spilling situation, to the change corresponding to current subgraph The transformation parameter of image after changing is adjusted；And if it is equal to 1 for the value of image pre-processing module transformation parameter, to each Subgraph carries out Lossless Compression processing and judges whether the code stream of current subgraph has spilling situation according to this, right if there is spilling situation Transformation parameter corresponding to current subgraph is adjusted.
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