CN100539700C - Method for encoding images and device - Google Patents
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Abstract
The embodiment of the invention relates to a kind of method for encoding images and device, and this method comprises: read the compressed bit stream of original image, the compressed bit stream of described original image is resolved, obtain the resolution of described original image; To carry out entropy decoding, counter-scanning through the compressed bit stream of resolving, obtain original dct coefficient matrix; According to the relation between the resolution of the resolution of described original image and display unit, determine the pattern that abandons of high frequency discrete cosine transform coefficient; Abandon corresponding high frequency discrete cosine transform coefficient according to the described pattern that abandons; Scan abandoning new dct coefficient matrix behind the high frequency discrete cosine transform coefficient, entropy coding, form the conversion code stream of compression, thereby saved memory space, reduced the picture decoding computational complexity, reduced cost and power consumption.
Description
Technical field
The present invention relates to the image coding and decoding field, especially a kind of method for encoding images and device.
Background technology
Development along with multimedia communication technology, people no longer satisfy the transmission of single literal or sound, from the plain old telephone to the visual telephone, from short message (Short Messaging Service, SMS) to enhanced short message (Enhanced Message Service, EMS) (MultimediaMessaging Service, MMS), multimedia technology progresses into huge numbers of families to arrive multimedia short message again.Therefore, how research handles multimedia source efficiently, allows its more convenient stores effectively and transmission is very important.(Joint Photographic Experts Group, JPEG) standard is applicable to the continually varying rest image as an important technology of image compression encoding to JPEG (joint photographic experts group), comprises the continuous variation of tonal gradation and color two aspects.
JPEG comprises two kinds of basic compression methods: a kind of is lossy compression method, is also referred to as discrete cosine transform (Discrete Cosine Transform, DCT) compression method; Another kind is a lossless compress, is also referred to as the prediction compression method.That normal use is the former, and promptly the DCT compression method can also be called baseline order encoding and decoding (Baseline Sequential Codec) method.As shown in Figure 1, in the prior art based on the JPEG of DCT coding schematic flow sheet.At first source image data is divided into the 8X8 block of pixels, is that unit encodes with the 8X8 block of pixels.Through forward discrete cosine transform (Forward DCT, FDCT) after, generates 64 DCT coefficients, these DCT coefficients are arranged according to the Zigzag order from the low frequency to the high frequency, first value is direct current (DC) coefficient, other 63 are interchange (AC) coefficient.High frequency coefficient is positioned at the lower right area of DCT coefficient matrix.Then, use the good quantization table that standardized that each DCT coefficient is quantized.The DC coefficient of last quantification is used to predict current DC coefficient, then its difference is encoded; 63 AC coefficients do not carry out differential coding.At last, the DCT coefficient is carried out entropy coding.The mode of entropy coding has two kinds, a kind of employing Huffman coded system, the another kind of arithmetic coding mode that adopts.Baseline uses the Huffman coding.In the FDCT transform and quantization, the loss that can introduce the precision of images is distortion.Because human eye is insensitive to high fdrequency component, and the high fdrequency component in the image is removed, compressed preferably, can obtain visual high fidelity image simultaneously.
The process and the cataloged procedure of decoding are opposite, as shown in Figure 2, in the prior art based on the JPEG decoding process schematic diagram of DCT.The decoding and displaying flow process of jpeg image comprises three steps, the i.e. demonstration of the decoding of the storage of image, image and image.The storage of image is exactly to utilize serial communication, USB interface or Ethernet data transmission to obtain the jpeg image packed data and deposit data in high-speed memory, as: flash memory (Flash), static random access memory (Static Random Access Memory, SRAM) etc.; The decoding process of image is opposite with above-mentioned coding flow process basically, mainly comprise preliminary treatment, Huffman (Huffman) decoding, inverse quantization, inverse discrete cosine transformation (Inverse Discrete CosineTransform, IDCT); The demonstration of image is that decoded view data is converted to rgb signal, and de-energisation picture tube (CRT) or LCDs (LCD) are finished the demonstration reduction of the display color of original image.
(Digital Photo Frame is a kind of mass consumption electronic product that is used for showing digital photograph DPF) to digital photo frame, is mainly used in the decoding and displaying jpeg image.Jpeg image can pass in the built-in flash memory of digital photo frame (Flash) by WiFi network, USB interface, also can be from the storage medium of extrapolation, include compact flash (Compact Flash, CF), memory stick (Memory Stick, MS), secure digital (Secure Digital, SD) card, multimedia (Multi Media, MMC) card, (Smart Media, SM), portable hard drive popular Flash cards such as (MicroDrive).
The picture size of the JPEG ASCII stream file ASCII of existing its input of DPF is usually much larger than the display resolution of LCDs, typically, the dimension of picture that digital camera is taken pictures out is 1024 * 768 to 4000 * 4000, and the LCDs of DPF is usually about 800 * 480, and low side DPF screen dimensions is lower.Therefore, can waste very big memory space when these cross high-resolution jpeg compressed image file in storage, and follow-up these are crossed can increase unnecessary computational complexity when high-resolution jpeg compressed image file is decoded by standard, thereby increased cost and power consumption.
Summary of the invention
The embodiment of the invention provides a kind of method for encoding images and device, stored the problem of the waste memory space that high-resolution compressed image file causes in order to solution, and the high problem of computational complexity that this image is decoded and caused, realize saving memory space, reduce the computational complexity of decoding, reduce cost and power consumption.
The embodiment of the invention provides a kind of method for encoding images, comprising:
Read the compressed bit stream of original image, the compressed bit stream of described original image is resolved, obtain the resolution of described original image;
To carry out entropy decoding, counter-scanning through the compressed bit stream of resolving, obtain original dct coefficient matrix;
According to the relation between the resolution of the resolution of described original image and display unit, determine the pattern that abandons of high frequency discrete cosine transform coefficient;
Abandon corresponding high frequency discrete cosine transform coefficient according to the described pattern that abandons;
Scan abandoning new dct coefficient matrix behind the high frequency discrete cosine transform coefficient, entropy coding, form the conversion code stream of compression.
The embodiment of the invention provides a kind of picture coding device, comprising:
First decoder module, be used to read the compressed bit stream of original image, the compressed bit stream of described original image is resolved, obtain the resolution of described original image, to carry out entropy decoding, counter-scanning through the compressed bit stream of resolving, obtain original dct coefficient matrix;
Processing module is used for determining the pattern that abandons of high frequency discrete cosine transform coefficient according to the relation between the resolution of the resolution of described original image and display unit, abandons corresponding high frequency discrete cosine transform coefficient according to the described pattern that abandons;
Coding module is used for scanning abandoning new dct coefficient matrix behind the high frequency discrete cosine transform coefficient, entropy coding, forms the conversion code stream of compression.
As shown from the above technical solution, behind the discrete cosine transform coefficient of the high frequency of the compressed bit stream of the embodiment of the invention by abandoning original image in advance, again it is encoded, stored the shared memory space of high-resolution compressed image file thereby saved, and reduced the computational complexity that this image is decoded, reduced cost and power consumption.
Description of drawings
Fig. 1 is based on the JPEG of DCT coding schematic flow sheet in the prior art;
Fig. 2 is based on the JPEG decoding process schematic diagram of DCT in the prior art;
Fig. 3 is the schematic flow sheet of first embodiment of method for encoding images of the present invention;
Fig. 4 is the schematic flow sheet of second embodiment of method for encoding images of the present invention;
Fig. 5 is the schematic flow sheet of the 3rd embodiment of method for encoding images of the present invention;
Fig. 6 is the schematic flow sheet of the 4th embodiment of method for encoding images of the present invention;
Fig. 7 is the structural representation of first embodiment of picture coding device of the present invention;
Fig. 8 is the structural representation of second embodiment of picture coding device of the present invention.
Embodiment
Below in conjunction with accompanying drawing specific embodiments of the invention are described in further detail.
As shown in Figure 3, be the schematic flow sheet of first embodiment of method for encoding images of the present invention.Present embodiment may further comprise the steps:
Behind the discrete cosine transform coefficient of the high frequency of the compressed bit stream of present embodiment by abandoning original image in advance, again it is encoded, stored the shared memory space of high-resolution compressed image file thereby saved, and reduced the computational complexity that this image is decoded, reduced cost and power consumption.
As shown in Figure 4, be the schematic flow sheet of second embodiment of method for encoding images of the present invention.Present embodiment may further comprise the steps:
In this step, DCT coefficient matrix for 8 * 8, can be according to the resolution of the resolution of original JPEG code stream and display unit such as LCD in level, vertical both direction ratio separately, determine level, vertical both direction abandon quantity after, abandon corresponding high frequency discrete cosine transform coefficient for the quantity that abandons according to determined level, vertical both direction.Wherein,
Horizontal direction abandon quantity be high frequency dct coefficient matrix abandon columns, i.e. M '=8-[8 * K/Sx], the span of M ' is [0,7], and is integer;
Vertical direction abandon quantity be high frequency dct coefficient matrix abandon line number, i.e. N '=8-[8 * K/Sy], the span of N ' is [0,7], and is integer;
Wherein, K is for considering the adjustment coefficient of display quality requirement, local memory capacity, decoding processing ability, and its span is [1,2]; Sx is the resolution of described original JPEG compressed bit stream and the resolution ratio in the horizontal direction of described display unit; Sy is the ratio of the resolution of the resolution of described original JPEG compressed bit stream and described display unit in vertical direction;
In this step, can the DCT coefficient matrix be dropped high frequency DCT coefficient be changed to 0 by the pattern of having determined that abandons.
For 8 * 8DCT coefficient matrix, remove to keep this DCT coefficient matrix upper left corner M * N (M=8-M '; N=8-N ') outside the DCT coefficient, abandon all the other coefficients, the M here, N are the positive integer between [1,8].
The pattern identification Mode that abandons in the present embodiment in the step 105 can be definite by following formula:
Abandon pattern identification Mode=N ' * 16+M '.
For example: as Sx, when Sy is 2, K gets 1.3 respectively, can determine that M ', N ' are 3, and promptly M, N are 5, promptly only keeps 5 * 5 the DCT coefficients in the upper left corner, and all the other coefficients then are dropped.It abandons pattern identification Mode is 51, is expressed as 0x33 with hexadecimal digit;
Amended conversion JPEG code stream is deposited in local NAND Flash or the storage card;
Step 108, show request, from local storage medium, read conversion JPEG code stream, the new jpeg file in the conversion JPEG code stream is resolved according to picture;
In the present embodiment, according to abandoning pattern corresponding high frequency DCT coefficient is put after 0, again after the DCT coefficient matrix is encoded, is stored, carry out follow-up decoding again, saved and stored the shared memory space of high-resolution jpeg compressed image file, reduce the operand when decoding once more, reduced cost and power consumption.
As shown in Figure 5, be the schematic flow sheet of the 3rd embodiment of method for encoding images of the present invention.Present embodiment may further comprise the steps:
In this step, DCT coefficient matrix for 8 * 8, can be according to the resolution of the resolution of original JPEG code stream and display unit such as LCD in level, vertical both direction ratio separately, determine level, vertical both direction abandon quantity after, abandon corresponding high frequency discrete cosine transform coefficient for the quantity that abandons according to determined level, vertical both direction.Wherein,
Horizontal direction abandon quantity be high frequency dct coefficient matrix abandon columns, i.e. M '=8-[8 * K/Sx], the span of M ' is [0,7], and is integer;
Vertical direction abandon quantity be high frequency dct coefficient matrix abandon line number, i.e. N '=8-[8 * K/Sy], the span of N ' is [0,7], and is integer;
Wherein, K is for considering the adjustment coefficient of display quality requirement, local memory capacity, decoding processing ability, and its span is [1,2]; Sx is the resolution of described original JPEG compressed bit stream and the resolution ratio in the horizontal direction of described display unit; Sy is the ratio of the resolution of the resolution of described original JPEG compressed bit stream and described display unit in vertical direction;
In this step, can the DCT coefficient matrix be dropped high frequency DCT coefficient be changed to 0 by the pattern of having determined that abandons.
For 8 * 8DCT coefficient matrix, remove to keep this DCT coefficient matrix upper left corner M * N (M=8-M '; N=8-N ') outside the DCT coefficient, abandon all the other coefficients, the M here, N are the positive integer between [1,8].
The pattern identification Mode that abandons in the present embodiment in the step 205 can be definite by following formula:
Abandon pattern identification Mode=N ' * 16+M '.
For example: as Sx, when Sy is 2, K gets 1.3 respectively, can determine that M ', N ' are 3, and promptly M, N are 5, promptly only keeps 5 * 5 the DCT coefficients in the upper left corner, and all the other coefficients then are dropped.It abandons pattern identification Mode is 51, is expressed as 0x33 with hexadecimal digit;
What step 507, storage described conversion JPEG code stream and this conversion JPEG code stream corresponding identification abandoned pattern abandons pattern identification Mode to local storage medium.
The method of wherein related storage has two kinds, a kind of is to describe in the head abandoning the jpeg file that pattern identification Mode adds conversion JPEG code stream to, and the band conversion JPEG ASCII stream file ASCII that abandons pattern identification Mode deposits among the local NAND Flash (or storage card) then; Another kind can be that amended conversion JPEG code stream is deposited among the local NAND Flash (or storage card), and add and to store the conversion code stream file into and abandon in the sign description list abandoning pattern identification Mode, abandon the sign description list at the conversion code stream file, each abandons the corresponding conversion code stream file of pattern identification data item.
Here no longer need the new whole coefficients of DCT coefficient matrix are carried out inverse quantization, IDCT, only need that the coefficient of pattern identification Mode to M * n-quadrant, the upper left corner in the DCT coefficient matrix (promptly remove in 8 * 8 coefficient matrixes do not put 0 high frequency DCT coefficient after residual coefficient) carries out inverse quantization, IDCT gets final product according to abandoning;
In the present embodiment, according to abandoning pattern high frequency DCT coefficient is put after 0, again to after the DCT coefficient matrix is encoded, is stored after revising, carry out follow-up simplification decoding according to the pattern that abandons again, saved and stored the shared memory space of high-resolution jpeg compressed image file, further reduce the follow-up computational complexity that this jpeg image is decoded, reduced cost and power consumption.
As shown in Figure 6, be the schematic flow sheet of the 4th embodiment of method for encoding images of the present invention.Different with the 3rd embodiment of method for encoding images of the present invention is that in the present embodiment, it is not the jpeg algorithm of employing standard that coding and secondary are decoded, and can be user-defined class jpeg algorithm.Present embodiment may further comprise the steps:
In this step, DCT coefficient matrix for 8 * 8, can be according to the resolution of the resolution of original JPEG code stream and display unit such as LCD in level, vertical both direction ratio separately, determine level, vertical both direction abandon quantity after, abandon corresponding high frequency discrete cosine transform coefficient for the quantity that abandons according to determined level, vertical both direction.Wherein,
Horizontal direction abandon quantity be high frequency dct coefficient matrix abandon columns, i.e. M '=8-[8 * K/Sx], the span of M ' is [0,7], and is integer;
Vertical direction abandon quantity be high frequency dct coefficient matrix abandon line number, i.e. N '=8-[8 * K/Sy], the span of N ' is [0,7], and is integer;
Wherein, K is for considering the adjustment coefficient of display quality requirement, local memory capacity, decoding processing ability, and its span is [1,2]; Sx is the resolution of described original JPEG compressed bit stream and the resolution ratio in the horizontal direction of described display unit; Sy is the ratio of the resolution of the resolution of described original JPEG compressed bit stream and described display unit in vertical direction.
For 8 * 8DCT coefficient matrix, remove to keep this DCT coefficient matrix upper left corner M * N (M=8-M '; N=8-N ') outside the DCT coefficient, abandon all the other coefficients, the M here, N are the positive integer between [1,8].
Except that above-mentioned rectangle abandons the pattern, also can abandon high frequency coefficient by the backward of Zig-Zag scanning;
Abandon under the pattern situation at rectangle, with 8 * 8DCT coefficient matrix, become except that M * N (M=8-M '; N=8-N ', M, N are the positive integer between [1,8]) coefficient matrix, the entry of a matrix element of this M * N is 8 * 8DCT coefficient matrix upper left corner M * N DCT coefficient.
The pattern identification Mode that abandons in the present embodiment in the step 305 can be definite by following formula:
Abandon pattern identification Mode=N ' * 16+M '.
For example: as Sx, when Sy is 2, K gets 1.3 respectively, can determine that M ', N ' are 3, and promptly M, N are 5, promptly only keeps 5 * 5 the DCT coefficients in the upper left corner, and all the other coefficients then are dropped.It abandons pattern identification Mode is 51, is expressed as 0x33 with hexadecimal digit;
Here new coefficient matrix size no longer is 8 * 8, but M * N (M, N are the positive integer between [1,8]).The scanning here can be the Zig-Zag scanning of still using in the Joint Photographic Experts Group to 8 * 8 matrixes, just skips the coefficient that has abandoned; Also can use other self-defining scanning algorithm.Here entropy coding can be a huffman coding; Also can use other entropy coding, as arithmetic coding;
What step 607, storage described conversion code stream and this conversion code stream corresponding identification abandoned pattern abandons pattern identification Mode to local storage medium.
The method of wherein related storage has two kinds, and a kind of is to abandon in the description head that pattern identification Mode adds the conversion code stream file to, then band abandon pattern identification Mode the conversion code stream file deposit among the local NAND Flash (or storage card); Another kind can be that amended conversion code stream is deposited among the local NAND Flash (or storage card), and add and to store the conversion code stream file into and abandon in the sign description list abandoning pattern identification Mode, abandon the sign description list at the conversion code stream file, each abandons the corresponding conversion code stream file of pattern identification data item;
Here entropy decoding is the inverse process of entropy coding in the step 306, and the counter-scanning here is the inverse process of scanning in the step 306, and the DCT coefficient matrix of conversion code stream is M * N matrix, M=8-M '; N=8-N ', M ' and N ' are the positive integer between [0,7], and M ' and N ' obtain by abandoning pattern identification Mode;
Abandon columns M ' and abandon line number N ' by abandoning pattern identification Mode acquisition high frequency coefficient, as obtaining M '=3 and N '=3, M=5 by Mode=0x33; N=5; Here only need carry out inverse quantization and IDCT, but the reconstructed image piece of IDCT output is 8 * 8 to 5 * 5 DCT coefficient matrix;
In the present embodiment, abandon after the high frequency DCT coefficient according to the pattern of abandoning, again after residue DCT coefficient matrix being encoded, is stored, carry out follow-up simplification decoding again, saved and stored the shared memory space of high-resolution compressed image, reduce the follow-up computational complexity that this compressed image is decoded, reduced cost and power consumption.
As shown in Figure 7, be the structural representation of first embodiment of picture coding device of the present invention.Present embodiment comprises first decoder module 10, processing module 20 and the coding module 30 that connects in turn.First decoder module 10 is used for receiving or reading from storage card from network the JPEG compressed bit stream of original image, compressed bit stream to original image is resolved, obtain the resolution of described original image, to carrying out Hofmann decoding, counter-scanning, obtain original DCT coefficient matrix through the compressed bit stream of resolving; Processing module 20 is used for according to the relation between the resolution of the resolution of described original image and display unit, determines the pattern that abandons of high frequency DCT coefficient, abandons corresponding high frequency DCT coefficient according to the described pattern that abandons; Coding module 30 is used for scanning abandoning new DCT coefficient matrix behind the high frequency DCT coefficient, entropy coding, forms the conversion code stream of compression.
In the present embodiment, discard module is divided after the corresponding high frequency DCT coefficient according to abandoning the pattern discarded part, again the DCT coefficient matrix is encoded by coding module, stored the shared memory space of high-resolution compressed image thereby saved, reduce the follow-up computational complexity that this compressed image is decoded, thereby reduced cost and power consumption.
Further, processing module 20 can comprise interconnective acquiring unit 21 and discarding unit 22 in the present embodiment.Wherein, acquiring unit 21 is used for according to the relation between the resolution of the resolution of described original image and display unit, determines the pattern that abandons of high frequency discrete cosine transform coefficient; The pattern that abandons that discarding unit 22 is used for obtaining according to described acquiring unit abandons corresponding high frequency discrete cosine transform coefficient.
DCT coefficient matrix for 8 * 8, acquiring unit 21 can be according to the resolution of the resolution of original JPEG code stream and display unit such as LCD in level, vertical both direction ratio separately, determine level, vertical both direction abandon quantity after, abandon corresponding high frequency discrete cosine transform coefficient for discarding unit 22 according to the quantity that abandons of acquiring unit 21 determined levels, vertical both direction.Correspondingly, acquiring unit 21 can comprise that abandoning columns obtains subelement and abandon line number and obtain subelement.Abandon columns and obtain subelement, be used for according to the relation between the horizontal resolution of the horizontal resolution of described original image and display unit, determine high frequency the DCT coefficient matrix abandon columns; Abandon line number and obtain subelement, be used for according to the relation between the vertical resolution of the vertical resolution of described original image and display unit, determine high frequency the DCT coefficient matrix abandon line number.Wherein,
Horizontal direction abandon quantity be high frequency dct coefficient matrix abandon columns, i.e. M '=8-[8 * K/Sx], the span of M ' is [0,7], and is integer;
Vertical direction abandon quantity be high frequency dct coefficient matrix abandon line number, i.e. N '=8-[8 * K/Sy], the span of N ' is [0,7], and is integer;
Wherein, K is for considering the adjustment coefficient of display quality requirement, local memory capacity, decoding processing ability, and its span is [1,2]; Sx is the resolution of described original JPEG compressed bit stream and the resolution ratio in the horizontal direction of described display unit; Sy is the ratio of the resolution of the resolution of described original JPEG compressed bit stream and described display unit in vertical direction.
Discarding unit 22 can be dropped high frequency DCT coefficient to the DCT coefficient matrix and be changed to 0 by the definite pattern that abandons of acquiring unit 21.For 8 * 8DCT coefficient matrix, remove to keep this DCT coefficient matrix upper left corner M * N (M=8-M '; N=8-N ') outside the DCT coefficient, discarding unit 22 abandons all the other coefficients, and the M here, N are the positive integer between [1,8].
The pattern identification Mode that abandons wherein can be definite by following formula:
Abandon pattern identification Mode=N ' * 16+M '.
For example: as Sx, when Sy is 2, K gets 1.3 respectively, can determine that M ', N ' are 3, and promptly M, N are 5, promptly only keeps 5 * 5 the DCT coefficients in the upper left corner, and all the other coefficients then are dropped.It abandons pattern identification Mode is 51, is expressed as 0x33 with hexadecimal digit.
As shown in Figure 8, be the structural representation of second embodiment of picture coding device of the present invention.On the basis of a last embodiment, present embodiment can also comprise memory module 40, second decoder module 50 and display module 60.Memory module 40 is used for the described conversion code stream that memory encoding module 30 is stored; Second decoder module 50 is used for reading the conversion code stream according to picture demonstration request from described memory module, and the described conversion code stream of decoding obtains decipher reestablishment image; Display module 60 is used for described decipher reestablishment image is carried out convergent-divergent and demonstration.
In the present embodiment, discard module is divided after the corresponding high frequency DCT coefficient according to abandoning the pattern discarded part, again the DCT coefficient matrix is encoded by coding module, after memory module is stored it, second decoder module carries out follow-up simplification decoding again, obtains to show behind the decipher reestablishment image, stores the shared memory space of high-resolution compressed image thereby saved, reduce the follow-up computational complexity that this compressed image is decoded, thereby reduced cost and power consumption.
Further, memory module 40 can also be used to store the pattern information that abandons of described conversion code stream correspondence in the present embodiment.
Further, second decoder module 50 can also be used for being abandoned inverse quantization, the inverse discrete cosine transformation that pattern information is simplified described new dct coefficient matrix according to what memory module 40 stored in the present embodiment.
In addition, one of ordinary skill in the art will appreciate that all or part of flow process that realizes in the foregoing description method, be to instruct relevant hardware to finish by program, described program can be stored in the computer read/write memory medium, this program can comprise the flow process as the embodiment of above-mentioned each side method when carrying out.Wherein, described storage medium can be magnetic disc, CD, read-only storage memory body (Read-OnlyMemory, ROM) or at random store memory body (Random Access Memory, RAM) etc.
It should be noted that at last: above embodiment only in order to technical scheme of the present invention to be described, is not intended to limit; Although with reference to previous embodiment the present invention is had been described in detail, those of ordinary skill in the art is to be understood that: it still can be made amendment to the technical scheme that aforementioned each embodiment put down in writing, and perhaps part technical characterictic wherein is equal to replacement; And these modifications or replacement do not make the essence of appropriate technical solution break away from the spirit and scope of various embodiments of the present invention technical scheme.
Claims (13)
1, a kind of method for encoding images is characterized in that comprising:
Read the compressed bit stream of original image, the compressed bit stream of described original image is resolved, obtain the resolution of described original image;
To carry out entropy decoding, counter-scanning through the compressed bit stream of resolving, obtain original dct coefficient matrix;
According to the relation between the resolution of the resolution of described original image and display unit, determine the pattern that abandons of high frequency discrete cosine transform coefficient;
Abandon corresponding high frequency discrete cosine transform coefficient according to the described pattern that abandons;
Scan abandoning new dct coefficient matrix behind the high frequency discrete cosine transform coefficient, entropy coding, form the conversion code stream of compression.
2, method for encoding images according to claim 1 is characterized in that described basis abandons pattern and abandons corresponding high frequency discrete cosine transform coefficient and specifically comprise:
According to the resolution of the resolution of described original image and described display unit ratio separately, determine the quantity that abandons of level, vertical both direction at level, vertical both direction;
The quantity that abandons according to described level, vertical both direction abandons corresponding high frequency discrete cosine transform coefficient.
3, method for encoding images according to claim 2 is characterized in that, when described dct coefficient matrix was 8 * 8 rank, the quantity that abandons of described horizontal direction comprised:
The dct coefficient matrix of high frequency abandon columns M '=8-[8 * K/Sx], M ' is the integer between 0～7, wherein, K is for adjusting coefficient, its span is 1～2; Sx is the resolution ratio in the horizontal direction of the resolution and the described display unit of described original image;
The quantity that abandons of described vertical direction comprises:
The dct coefficient matrix of high frequency abandon line number N '=8-[8 * K/Sy], N ' is the integer between 0～7, wherein, K is for adjusting coefficient, its span is 1～2; Sy is the ratio of the resolution of the resolution of described original image and described display unit in vertical direction.
4, coding method according to claim 1 is characterized in that describedly scanning abandoning new dct coefficient matrix behind the high frequency discrete cosine transform coefficient, entropy coding, also comprises after forming the conversion code stream of compression:
Store described conversion code and flow to local storage medium;
From local storage medium, read the corresponding conversion code stream that has deposited local storage medium in according to picture demonstration request;
The described conversion code stream of decoding obtains decipher reestablishment image;
Described decipher reestablishment image is carried out convergent-divergent and demonstration.
5, method for encoding images according to claim 4 is characterized in that the described conversion code of described storage flows to local storage medium and specifically comprises: that stores described conversion code stream and described conversion code stream correspondence abandons pattern information to local storage medium;
Show that according to picture asking to read the corresponding conversion code stream that has deposited local storage medium in from local storage medium specifically comprises: show according to picture and ask from local storage medium, to read corresponding conversion code stream and the described pattern information that abandons that has deposited local storage medium in;
The described conversion code stream of described decoding obtains decipher reestablishment image and specifically comprises: according to the described pattern information that abandons described conversion code stream is decoded.
6, method for encoding images according to claim 5 is characterized in that the described pattern information that abandons specifically comprises and abandons pattern identification, describedly abandons the function that abandons quantity that abandons quantity and described vertical direction that pattern identification is described horizontal direction.
7,, it is characterized in that the described conversion code stream of described decoding obtains decipher reestablishment image and specifically comprises according to claim 5 or 6 described method for encoding images:
The analytic trnasformation code stream carries out entropy decoding, counter-scanning, obtains new dct coefficient matrix;
Described new dct coefficient matrix is carried out inverse quantization, inverse discrete cosine transformation, obtain decipher reestablishment image.
8, a kind of picture coding device is characterized in that comprising:
First decoder module, be used to read the compressed bit stream of original image, the compressed bit stream of described original image is resolved, obtain the resolution of described original image, to carry out entropy decoding, counter-scanning through the compressed bit stream of resolving, obtain original dct coefficient matrix;
Processing module is used for determining the pattern that abandons of high frequency discrete cosine transform coefficient according to the relation between the resolution of the resolution of described original image and display unit, abandons corresponding high frequency discrete cosine transform coefficient according to the described pattern that abandons;
Coding module is used for scanning abandoning new dct coefficient matrix behind the high frequency discrete cosine transform coefficient, entropy coding, forms the conversion code stream of compression.
9, picture coding device according to claim 8 is characterized in that described processing module comprises:
Acquiring unit is used for determining the pattern that abandons of high frequency discrete cosine transform coefficient according to the relation between the resolution of the resolution of described original image and display unit;
Discarding unit, the pattern that abandons that is used for obtaining according to described acquiring unit abandons corresponding high frequency discrete cosine transform coefficient.
10, picture coding device according to claim 9 is characterized in that, when described dct coefficient matrix was 8 * 8 rank, described acquiring unit comprised:
Abandon columns and obtain subelement, be used for according to the relation between the horizontal resolution of the horizontal resolution of described original image and display unit, determine high frequency dct coefficient matrix abandon columns, the described columns M '=8-[8 * K/Sx that abandons], M ' is the integer between 0～7, wherein, K is for adjusting coefficient, and its span is 1～2; Sx is the resolution ratio in the horizontal direction of the resolution and the described display unit of described original image;
Abandon line number and obtain subelement, be used for according to the relation between the vertical resolution of the vertical resolution of described original image and display unit, determine high frequency dct coefficient matrix abandon line number, the described line number N '=8-[8 * K/Sy that abandons], N ' is the integer between 0～7, wherein, K is for adjusting coefficient, and its span is 1～2; Sy is the ratio of the resolution of the resolution of described original image and described display unit in vertical direction.
11, picture coding device according to claim 8 is characterized in that described picture coding device also comprises:
Memory module is used to store the conversion code stream that described coding module generates;
Second decoder module is used for reading described conversion code stream according to picture demonstration request from described memory module, and the described conversion code stream of decoding obtains decipher reestablishment image;
Display module is used for described decipher reestablishment image is carried out convergent-divergent and demonstration.
12, picture coding device according to claim 11 is characterized in that described memory module also is used to store the pattern information that abandons of described conversion code stream correspondence.
13, picture coding device according to claim 12 is characterized in that described second decoder module also is used for according to the pattern information that abandons that described memory module is stored described new dct coefficient matrix being carried out inverse quantization, inverse discrete cosine transformation.
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| WO2022041206A1 (en) * | 2020-08-31 | 2022-03-03 | 深圳市大疆创新科技有限公司 | Image encoding method and apparatus, image decoding method and apparatus, and storage medium |
| CN112767503B (en) * | 2021-01-15 | 2022-08-12 | 北京航空航天大学 | JPEG compression coding-based digital pathology full-slice image rapid analysis method |
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