CN101588497A - Frame buffering data compression and decompression method and circuit for LCD overdrive - Google Patents

Abstract

The invention provides a frame buffering data compression method flow chart for LCD overdrive, including the following steps: executing 2X2 partitioning for the video image, calculating the gradient of the R, G and B color components of the present block in the partitioned video image in the horizontal direction and in the perpendicular direction, obtaining the maximum value of the gradient in horizontal direction and in the perpendicular direction; judging that the gradient of the present block is in the greyscale slow change according to the maximum value of the gradient in horizontal direction and in the perpendicular direction, and executing the gradient increment encoding for the present block according to the gradient. The invention solves the problem in the prior art that the larger block is needed for obtaining over three times of compression ratio, however the larger block size causes the decrease of the compressibility, further the glitter, the step and the like can appear when the bigger anamorphic former frame decompression data is used to execute OverDrive, the movement at the speed being not equal to one half of the block size exists.

Description

Be used for the compression of frame buffered data, decompression method and circuit that LCD overdrives

Technical field

The present invention relates to image processing field, the compression of frame buffered data, decompression method and the circuit of overdriving in particular to a kind of LCD of being used for.

Background technology

Because LCD (Liquid Crystal Display, LCD) sampling keeps principle and liquid crystal molecule itself than CRT (Cathode Ray Tube, cathode ray tube) slow-response characteristic makes LCD when showing motion video image, motion blur can occur.

For reducing motion blur, generally adopt response time to LCD to compensate that (Response Time Compensation is RTC) as the method for removing motion blur.Wherein, (Over Drive) technology of overdriving is a kind of comparatively simple and highly effective technology, and its principle is to overdrive according to the view data of adjacent two frames to table look-up.Therefore OverDrive needs the outer RAM of sheet to store at least one two field picture packed data, for reducing the outer RAM capacity of sheet and to the demand of bandwidth, need carry out the encoding compression storage to the view data of present frame, also need the code stream of former frame is decompressed at Over Drive end.In order to reduce the ram in slice storage overhead, common way is that image is divided into 2*4,1*4, and the asymmetric fritter of length and width such as 1*8 carries out compressed encoding respectively to each piece then.For requirement of real time, the compression algorithm that is adopted all is based on lower piecemeal cut position coding (the Block Truncation Coding of complexity basically, BTC), or each component of RGB carried out compressed encoding respectively, or earlier the RGB component is transformed into the YUV territory, then the YUV component is carried out compression coding and decoding respectively according to different weights.

In realizing process of the present invention, the inventor finds in the prior art in order to obtain compression ratio higher more than 3 times, just need bigger piecemeal, yet bigger block size, cause the decline of compression performance, when the former frame decompressed data that adopts big distortion is carried out OverDrive, exist in the video be not equal to block size half/during the speed motion of frame, phenomenons such as flicker, step can appear.

Summary of the invention

The present invention aims to provide the compression of frame buffered data, decompression method and the circuit that a kind of LCD of being used for overdrives, can solve in the prior art in order to obtain compression ratio higher more than 3 times, just need bigger piecemeal, yet bigger block size, cause the decline of compression performance, when the former frame decompressed data that adopts big distortion is carried out OverDrive, exist in the video be not equal to block size half/during the speed motion of frame, flicker, the problem of phenomenons such as step can appear.

In an embodiment of the present invention, the frame buffered data compression method that provides a kind of LCD of being used for to overdrive may further comprise the steps:

Video image is carried out 2 * 2 piecemeals;

R, G, the B color component that calculates the current block of piecemeal rear video image in the horizontal direction with the gradient of vertical direction, obtain the maximum of the gradient of horizontal direction and vertical direction;

When the maximum according to the gradient of horizontal direction and vertical direction, the gradient of judging current block is gray scale when gradual, according to gradient current block is carried out the gradient incremental encoding.

Preferably, in above-mentioned frame buffered data compression method, R, G, the B color component that calculates the current block of piecemeal rear video image in the horizontal direction with the gradient of vertical direction, the maximum that obtains the gradient of horizontal direction and vertical direction specifically comprises:

Calculate current block gradient in the horizontal direction:

$\mathrm{\ΔR}\_x=\left\{\begin{array}{c}|R_{11}-R_{12}|\\ |R_{21}-R_{22}|\end{array}\right\},$ $\mathrm{\ΔG}\_x=\left\{\begin{array}{c}{|G}_{11}-G_{12}|\\ |G_{21}-G_{22}|\end{array}\right\},$ $\mathrm{\ΔB}\_x=\left\{\begin{array}{c}|B_{11}-B_{12}|\\ |B_{21}-B_{22}|\end{array}\right\};$

Calculate the gradient of current block in vertical direction:

$\mathrm{\ΔR}\_y=\left\{\begin{array}{c}|R_{11}-R_{21}|\\ |R_{12}-R_{22}|\end{array}\right\},$ $\mathrm{\ΔG}\_y=\left\{\begin{array}{c}{|G}_{11}-G_{21}|\\ |G_{12}-G_{22}|\end{array}\right\},$ $\mathrm{\ΔB}\_y=\left\{\begin{array}{c}|B_{11}-B_{21}|\\ |B_{12}-B_{22}|\end{array}\right\};$

According to current block in the horizontal direction with the gradient of vertical direction, obtain current block in the horizontal direction with the maximum of the gradient of vertical direction:

$\left\{\begin{array}{c}\mathrm{\Δ}\_x\_\max =\max \{\mathrm{\ΔR}\_x,\mathrm{\ΔG}\_x,\mathrm{\ΔB}\_x\}\\ \mathrm{\Δ}\_y\_\max =\max \{\mathrm{\ΔR}\_y,\mathrm{\ΔG}\_y,\mathrm{\ΔB}\_y\}\end{array}\right.;$

Wherein, current block is expressed as $\left[\begin{array}{cc}{X}_{11}(R_{11},G_{11},B_{11})& X_{12}(R_{12},G_{12},B_{12})\\ X_{21}(R_{21},G_{21},B_{21})& X_{22}(R_{22},G_{22},B_{22})\end{array}\right],$ Horizontal direction is the x direction of principal axis, and vertical direction is the y direction of principal axis.

Preferably, in above-mentioned frame buffered data compression method, whether the gradient of judging current block is that the formula of the gradual gradient of gray scale is:

$\left\{\begin{array}{ccc}\mathrm{EncodeType}=1,\mathrm{if}& 0<\mathrm{\&Delta;}\_x\_\max \&le;7,\mathrm{or}& 0<\mathrm{\&Delta;}\_y\_\max \&le;7\\ \mathrm{EncodeType}=0,& \mathrm{others}& \end{array}\right.;$

Wherein, EncodeType=1 represents that the gradient of current block is the gradual gradient of gray scale, and EncodeType=0 represents that the gradient of current block is not the gradual gradient of gray scale.

Preferably, in above-mentioned frame buffered data compression method, the judgment formula of the gradient direction of current block is:

$\left\{\begin{array}{cc}\mathrm{Grad}\_\mathrm{dir}=0,\mathrm{if}& \mathrm{\&Delta;}\_x\_\max \&GreaterEqual;\mathrm{\&Delta;}\_y\_\max \\ \mathrm{Grad}\_\mathrm{dir}=1,\mathrm{if}& \mathrm{\&Delta;}\_x\_\max <\mathrm{\&Delta;}\_y\_\max \end{array}\right.;$

Wherein, Grad_dir=0 represents that the gradient direction of current block is the x axle, and Grad_dir=1 represents that the gradient direction of current block is the y direction of principal axis.

Preferably, in above-mentioned frame buffered data compression method, when the maximum according to the gradient of horizontal direction and vertical direction, the gradient of judging current block is gray scale when gradual, according to gradient current block is carried out the gradient incremental encoding and specifically comprises:

Adopt the 32bit code stream that current block is carried out the gradient incremental encoding, wherein, the 32bit code stream comprises: 1bit type of coding EncodeType, 22bit piecemeal priming color C ₁₁(R ₁₁G ₁₁B ₁₁), 1bit gradient direction flag bit Grad_dir, 3bit RGB compensation flag bit rgb_compflag[2:0], 3bit gradient increase and decrease symbol position rgb_delta_sign[2:0] and 2bit gradient data position delta[1:0];

Wherein, EncodeType represents the coding method adopted, and the ColorBTC coding method is adopted in ' 0 ' expression, and gradient incremental encoding method is adopted in ' 1 ' expression; Piecemeal priming color X ₁₁(R ₁₁G ₁₁B ₁₁) represent R with 7bit, 8bit and 7bit respectively ₁₁, G ₁₁, B ₁₁Grad_dir be 0 expression level to gradient, be 1 the expression vertically to gradient; Rgb_compflag[2:0] represent whether R, G, three components of B exist gradient; Rgb_delta_sign[2:0] the gradient increment sign of expression R, G, three components of B; Delta[1:0] be gradient numerical value, scope is 0-3.

Preferably, in above-mentioned frame buffered data compression method, when gradient direction when the x direction of principal axis is Grad_dir=0, gradient increase and decrease symbol position rgb_delta_sign[2:0] the generation formula be:

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=0& \mathrm{if}& \mathrm{\&Delta;R}\_x<\mathrm{\&Delta;}\_x\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=1& \mathrm{if}& \mathrm{\&Delta;R}\_x>=\mathrm{\&Delta;}\_x\_\max /2\end{array}\right.;$

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=0& \mathrm{if}& \mathrm{\&Delta;G}\_x<\mathrm{\&Delta;}\_x\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=1& \mathrm{if}& \mathrm{\&Delta;G}\_x>=\mathrm{\&Delta;}\_x\_\max /2\end{array}\right.;$

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=0& \mathrm{if}& \mathrm{\&Delta;B}\_x<\mathrm{\&Delta;}\_x\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=1& \mathrm{if}& \mathrm{\&Delta;B}\_x>=\mathrm{\&Delta;}\_x\_\max /2\end{array}\right..$

When gradient direction when the x direction of principal axis is Grad_dir=0, gradient increase and decrease symbol position rgb_delta_sign[2:0] the generation formula be:

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=0& \mathrm{if}& \mathrm{\&Delta;R}\_y<\mathrm{\&Delta;}\_y\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=1& \mathrm{if}& \mathrm{\&Delta;R}\_y>=\mathrm{\&Delta;}\_y\_\max /2\end{array}\right.;$

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=0& \mathrm{if}& \mathrm{\&Delta;G}\_y<\mathrm{\&Delta;}\_y\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=1& \mathrm{if}& \mathrm{\&Delta;G}\_y>=\mathrm{\&Delta;}\_y\_\max /2\end{array}\right.;$

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=0& \mathrm{if}& \mathrm{\&Delta;B}\_y<\mathrm{\&Delta;}\_y\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=1& \mathrm{if}& \mathrm{\&Delta;B}\_y>=\mathrm{\&Delta;}\_y\_\max /2\end{array}\right..$

Preferably, in above-mentioned frame buffered data compression method, further comprising the steps of:

When the maximum according to the gradient of horizontal direction and vertical direction, the gradient of judging current block is not gray scale when gradual, according to gradient current block is carried out Color BTC coding.

In an embodiment of the present invention, the frame buffered data decompression method that also provides a kind of LCD of being used for to overdrive may further comprise the steps:

Obtain type of coding EncodeType according to block code stream;

When EncodeType=1 ' b1, from code stream, obtain the initial point X of 2*2 piecemeal ₁₁(R ₁₁G ₁₁B ₁₁) gradient direction Grad_dir, increment sign rgb_delta_sign[2:0], increment numerical value delta[1:0] and three color components compensation of R, G, B flag bit rgb_compflag[2:0], to initial point X ₁₁(R ₁₁G ₁₁B ₁₁) rebuild:

$\left\{\begin{array}{c}\mathrm{red}\_\mathrm{delta}=(!\mathrm{rgb}\_\mathrm{delta}\_\mathrm{sign}[2\left]\right)?\mathrm{delta}:-\mathrm{delta}\\ \mathrm{gre}\_\mathrm{delta}=(!\mathrm{rgb}\_\mathrm{delta}\_\mathrm{sign}[1\left]\right)?\mathrm{delta}:-\mathrm{delta}\\ \mathrm{blu}\_\mathrm{delta}=(!\mathrm{rgb}\_\mathrm{delta}\_\mathrm{sign}[0\left]\right)?\mathrm{delta}:-\mathrm{delta}\end{array}\right.;$

When gradient direction is that the x direction of principal axis is when being Grad_dir==1 ' b0, to other data point X in the code stream block ₁₂(R ₁₂G ₁₂B ₁₂), X ₂₁(R ₂₁G ₂₁B ₂₁) and X ₂₂(R ₂₂G ₂₂B ₂₂) rebuild respectively:

$\left\{\begin{array}{c}{R}_{12}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{12}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0)\\ B_{12}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right.;$

$\left\{\begin{array}{c}{R}_{21}=R_{11}\\ G_{21}=G_{11}\\ B_{21}=B_{11}\end{array}\right.;$

$\left\{\begin{array}{c}{R}_{22}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{22}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0)\\ B_{22}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right.;$

When gradient direction is that the y direction of principal axis is to being Grad_dir==1 ' b1, to other data point X in the code stream block ₁₂(R ₁₂G ₁₂B ₁₂), X ₂₁(R ₂₁G ₂₁B ₂₁) and X ₂₂(R ₂₂G ₂₂B ₂₂) rebuild respectively:

$\left\{\begin{array}{c}{R}_{12}=R_{11}\\ G_{12}=G_{11}\\ B_{12}=B_{11}\end{array}\right.;$

$\left\{\begin{array}{c}{R}_{21}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{21}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0)\\ B_{21}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right.;$

$\left\{\begin{array}{c}{R}_{22}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{22}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0)\\ B_{22}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right..$

Preferably, in above-mentioned frame buffered data decompression method, further comprising the steps of:

When EncodeType=1 ' b0, from code stream, obtain the 4bit classified information of two classification look C0, C1 and the corresponding piecemeal of code stream;

Code stream is carried out Color BTC decoding, obtain the decoded data of piecemeal.

In an embodiment of the present invention, the circuit that also provides a kind of LCD of being used for to overdrive comprises: compression module, sheet external memory module, decompression module, judge module and look-up table means, wherein

Compression module is used for the current block of current frame video image is compressed, and stores compressed code flow into sheet external memory module;

Decompression module, the block code that is used for the corresponding former frame video image of decompress(ion) and current block flows;

Judge module is used for current block code stream and former frame corresponding blocks code stream are compared, and then judges whether current block is static block;

Look-up table means is overdrived to the current block data and the corresponding former frame decompression block data of non-static block.

In the above-described embodiments, by video image is adopted the 2*2 piecemeal, no matter great movement velocity, also no matter the direction of motion how, all the integral multiple of piece size half (1 pixel) on the numerical value, therefore scintillation can not appear, overcome in the prior art in order to obtain compression ratio higher more than 3 times, just need bigger piecemeal, yet bigger block size causes the decline of compression performance, when the former frame decompressed data that adopts big distortion is carried out OverDrive, exist in the video be not equal to block size half/during the speed motion of frame, scintillation can appear, problems such as step.

Description of drawings

Accompanying drawing described herein is used to provide further understanding of the present invention, constitutes the application's a part, and illustrative examples of the present invention and explanation thereof are used to explain the present invention, do not constitute improper qualification of the present invention.In the accompanying drawings:

Fig. 1 shows and is used for the frame buffered data compression method flow chart that LCD overdrives according to an embodiment of the invention;

Fig. 2 shows and is used for the frame buffered data decompression method flow chart that LCD overdrives according to an embodiment of the invention;

Fig. 3 shows and is used for the circuit module figure that LCD overdrives according to an embodiment of the invention;

Fig. 4 shows the frame buffer compression overdrive circuit schematic diagram that is used for LCD in accordance with a preferred embodiment of the present invention.

Embodiment

Below with reference to the accompanying drawings and in conjunction with the embodiments, describe the present invention in detail.

Fig. 1 shows and is used for the frame buffered data compression method flow chart that LCD overdrives according to an embodiment of the invention, may further comprise the steps:

S102 carries out 2 * 2 piecemeals to video image;

S104, R, G, the B color component that calculates the current block of piecemeal rear video image in the horizontal direction with the gradient of vertical direction, obtain the maximum of the gradient of horizontal direction and vertical direction;

S106, when the maximum according to the gradient of horizontal direction and vertical direction, the gradient of judging current block is gray scale when gradual, according to above-mentioned gradient current block is carried out the gradient incremental encoding.

In the present embodiment, by video image is adopted the 2*2 piecemeal, no matter great movement velocity, also no matter the direction of motion how, all the integral multiple of piece size half (1 pixel) on the numerical value, therefore scintillation can not appear, overcome in the prior art in order to obtain 3 times with first-class higher compression ratio, just need bigger piecemeal, yet bigger block size causes the decline of compression performance, when the former frame decompressed data that adopts big distortion is carried out OverDrive, exist in the video be not equal to block size half/during the speed motion of frame, flicker can appear, the problem of phenomenons such as step.

Simultaneously, adopt the gradient incremental encoding can adapt to the required precision of gradual gradient image or close grain image preferably.

The data block of 2*2 $\left[\begin{array}{cc}{X}_{11}(R_{11},G_{11},B_{11})& X_{12}(R_{12},G_{12},G_{12})\\ X_{21}(R_{21},G_{21},B_{21})& X_{22}(R_{22},G_{22},B_{22})\end{array}\right]$ The gradient that may exist has the gradient combination of following one or more color components:

Level to: $\left\{\begin{array}{c}{R}_{11}\&RightArrow;R_{12}\\ R_{21}\&RightArrow;R_{22}\end{array}\right\},$ $\left\{\begin{array}{c}{G}_{11}\&RightArrow;G_{12}\\ G_{21}\&RightArrow;G_{22}\end{array}\right\},$ $\left\{\begin{array}{c}{B}_{11}\&RightArrow;B_{12}\\ B_{21}\&RightArrow;B_{22}\end{array}\right\};$

Vertically to: $\left\{\begin{array}{c}{R}_{11}\&RightArrow;R_{12}\\ R_{12}\&RightArrow;R_{22}\end{array}\right\},$ $\left\{\begin{array}{c}{G}_{11}\&RightArrow;G_{21}\\ G_{12}\&RightArrow;G_{22}\end{array}\right\},$ $\left\{\begin{array}{c}{B}_{11}\&RightArrow;B_{21}\\ B_{12}\&RightArrow;B_{22}\end{array}\right\}.$

Preferably, in above-mentioned frame buffered data compression method, R, G, the B color component that calculates the current block of piecemeal rear video image in the horizontal direction with the gradient of vertical direction, the maximum that obtains the gradient of horizontal direction and vertical direction specifically comprises:

Calculate current block gradient in the horizontal direction:

$\mathrm{\&Delta;R}\_x=\left\{\begin{array}{c}{|R}_{11}-R_{12}|\\ {|R}_{21}-R_{22}|\end{array}\right\},$ $\mathrm{\&Delta;G}\_x=\left\{\begin{array}{c}|G_{11}-G_{12}|\\ {|G}_{21}-G_{22}|\end{array}\right\},$ $\mathrm{\&Delta;B}\_x=\left\{\begin{array}{c}|B_{11}-B_{12}|\\ |B_{21}-B_{22}|\end{array}\right\};$

Calculate the gradient of current block in vertical direction:

$\mathrm{\&Delta;R}\_y=\left\{\begin{array}{c}|R_{11}-R_{21}|\\ |R_{12}-R_{22}|\end{array}\right\},$ $\mathrm{\&Delta;G}\_y=\left\{\begin{array}{c}|G_{11}-G_{21}|\\ {|G}_{21}-G_{22}|\end{array}\right\},$ $\mathrm{\&Delta;B}\_y=\left\{\begin{array}{c}|B_{11}-B_{21}|\\ |B_{12}-B_{22}|\end{array}\right\};$

According to current block in the horizontal direction with the gradient of vertical direction, obtain current block in the horizontal direction with the maximum of the gradient of vertical direction:

$\left\{\begin{array}{c}\mathrm{\&Delta;}\_x\_\max =\max \{\mathrm{\&Delta;R}\_x,\mathrm{\&Delta;G}\_x,\mathrm{\&Delta;B}\_x\}\\ \mathrm{\&Delta;}\_y\_\max =\max \{\mathrm{\&Delta;R}\_y,\mathrm{\&Delta;G}\_y,\mathrm{\&Delta;B}\_y\}\end{array}\right.;$

Wherein, current block is expressed as $\left[\begin{array}{cc}{X}_{11}(R_{11},G_{11},B_{11})& X_{12}(R_{12},G_{12},B_{12})\\ X_{21}(R_{21},G_{21},B_{21})& X_{22}(R_{22},G_{22},B_{22})\end{array}\right],$ Horizontal direction is the x direction of principal axis, and vertical direction is the y direction of principal axis.

Preferably, in above-mentioned frame buffered data compression method, whether the gradient of judging current block is that the formula of the gradual gradient of gray scale is:

$\left\{\begin{array}{ccc}\mathrm{EncodeTyp}=1,\mathrm{if}& 0<\mathrm{\&Delta;}\_x\_\max \&le;7,\mathrm{or}& 0<\mathrm{\&Delta;}\_y\_\max \&le;7\\ \mathrm{EncodeType}=0,& \mathrm{others}& \end{array}\right.;$

Wherein, EncodeType=1 represents that the gradient of current block is the gradual gradient of gray scale, and EncodeType=0 represents that the gradient of current block is not the gradual gradient of gray scale.

Preferably, in above-mentioned frame buffered data compression method, the judgment formula of the gradient direction of current block is:

$\left\{\begin{array}{cc}\mathrm{Grad}\_\mathrm{dir}=0,\mathrm{if}& \mathrm{\&Delta;}\_x\_\max \&GreaterEqual;\mathrm{\&Delta;}\_y\_\max \\ \mathrm{Grad}\_\mathrm{dir}=1,\mathrm{if}& \mathrm{\&Delta;}\_x\_\max <\mathrm{\&Delta;}\_y\_\max \end{array}\right.;$

Wherein, Grad_dir=0 represents that the gradient direction of current block is the x axle, and Grad_dir=1 represents that the gradient direction of current block is the y direction of principal axis.

Preferably, in above-mentioned frame buffered data compression method, when the maximum according to the gradient of horizontal direction and vertical direction, the gradient of judging current block is gray scale when gradual, according to gradient current block is carried out the gradient incremental encoding and specifically comprises:

Adopt the 32bit code stream that current block is carried out the gradient incremental encoding, wherein, the 32bit code stream comprises: 1bit type of coding EncodeType, 22bit piecemeal priming color C ₁₁(R ₁₁G ₁₁B ₁₁), 1bit gradient direction flag bit Grad_dir, 3bit RGB compensation flag bit rgb_compflag[2:0], 3bit gradient increase and decrease symbol position rgb_delta_sign[2:0] and 2bit gradient data position delta[1:0];

Wherein, EncodeType represents the coding method adopted, and the ColorBTC coding method is adopted in ' 0 ' expression, and gradient incremental encoding method is adopted in ' 1 ' expression; Piecemeal priming color X ₁₁(R ₁₁G ₁₁B ₁₁) represent R with 7bit, 8bit and 7bit respectively ₁₁, G ₁₁, B ₁₁Grad_dir be 0 expression level to gradient, be 1 the expression vertically to gradient; Rgb_compflag[2:0] represent whether R, G, three components of B exist gradient; Rgb_delta_sign[2:0] the gradient increment sign of expression R, G, three components of B; Delta[1:0] be gradient numerical value, scope is 0-3.

Preferably, in above-mentioned frame buffered data compression method, when gradient direction when the x direction of principal axis is Grad_dir=0, gradient increase and decrease symbol position rgb_delta_sign[2:0] the generation formula be:

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=0& \mathrm{if}& \mathrm{\&Delta;R}\_x<\mathrm{\&Delta;}\_x\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=1& \mathrm{if}& \mathrm{\&Delta;R}\_x>=\mathrm{\&Delta;}\_x\_\max /2\end{array}\right.;$

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=0& \mathrm{if}& \mathrm{\&Delta;G}\_x<\mathrm{\&Delta;}\_x\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=1& \mathrm{if}& \mathrm{\&Delta;G}\_x>=\mathrm{\&Delta;}\_x\_\max /2\end{array}\right.;$

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=0& \mathrm{if}& \mathrm{\&Delta;B}\_x<\mathrm{\&Delta;}\_x\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=1& \mathrm{if}& \mathrm{\&Delta;B}\_x>=\mathrm{\&Delta;}\_x\_\max /2\end{array}\right..$

When gradient direction when the x direction of principal axis is Grad_dir=0, gradient increase and decrease symbol position rgb_delta_sign[2:0] the generation formula be:

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=0& \mathrm{if}& \mathrm{\&Delta;R}\_y<\mathrm{\&Delta;}\_y\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=1& \mathrm{if}& \mathrm{\&Delta;R}\_y>=\mathrm{\&Delta;}\_y\_\max /2\end{array}\right.;$

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=0& \mathrm{if}& \mathrm{\&Delta;G}\_y<\mathrm{\&Delta;}\_y\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=1& \mathrm{if}& \mathrm{\&Delta;G}\_y>=\mathrm{\&Delta;}\_y\_\max /2\end{array}\right.;$

$\left\{\begin{array}{ccc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=0& \mathrm{if}& \mathrm{\&Delta;B}\_y<\mathrm{\&Delta;}\_y\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=1& \mathrm{if}& \mathrm{\&Delta;B}\_y>=\mathrm{\&Delta;}\_y\_\max /2\end{array}\right..$

Preferably, in above-mentioned frame buffered data compression method, further comprising the steps of:

When the maximum according to the gradient of horizontal direction and vertical direction, the gradient of judging current block is not gray scale when gradual, according to gradient current block is carried out Color BTC coding.

Color BTC encoding-decoding process is as follows:

By R, G, B color component the pixel in the vedio data current block is divided into two classes;

Write down two classes classification look C0 (R0, G0, BO) and C1 (R1, G1, B1), and the affiliated classified information of pixel.

Preferably, in above-mentioned Color BTC video encoding method, two classes classification look C0 (R0, G0, BO) and C1 (R1, G1 B1) make the interior error in classification minimum of vedio data piecemeal.

Preferably, in above-mentioned Color BTC video encoding method, vedio data is carried out piecemeal specifically comprises:

Vedio data is carried out 2 * 2 piecemeals, obtain four pixel X in the vedio data piecemeal ₁₁(R ₁₁, G ₁₁, B ₁₁), X ₁₂(R ₁₂, G ₁₂, B ₁₂), X ₂₁(R ₂₁, G ₂₁, B ₂₁) and X ₂₂(R ₂₂, G ₂₂, B ₂₂).

Preferably, in above-mentioned Color BTC video encoding method, the pixel in the vedio data piecemeal is divided into two classes specifically comprises by R, G, B color component:

Four pixels are divided into A, B two classes;

The classification look of sorted pixel is replaced with center of mass point in the class of classification, is specially:

A(X ₁₁)，B(X ₁₂，X ₂₁，X ₂₂)，X _{A_1}＝X ₁₁， $X_{B\_1}=\frac{X_{12}+X_{21}+X_{22}}{3};$

A(X ₁₂)，B(X ₁₁，X ₂₁，X ₂₂)，X _{A_2}＝X ₁₂， $X_{B\_2}=\frac{X_{11}+X_{21}+X_{22}}{3};$

A(X ₂₁)，B(X ₁₁，X ₁₂，X ₂₂)，X _{A_3}＝X ₂₁， $X_{B\_3}=\frac{X_{11}+X_{12}+X_{22}}{3};$

A(X ₂₂)，B(X ₁₁，X ₁₂，X ₂₁)，X _{A_4}＝X ₂₂， $X_{B\_4}=\frac{X_{11}+X_{12}+X_{21}}{3};$

A(X ₁₁，X ₁₂)，B(X ₂₁，X ₂₂)， $X_{A\_5}=\frac{X_{11}+X_{12}}{2},$ $X_{B\_5}=\frac{X_{21}+X_{22}}{2};$

A(X ₁₁，X ₂₁)，B(X ₁₂，X ₂₂)， $X_{A\_6}=\frac{X_{11}+X_{21}}{2},$ $X_{B\_6}=\frac{X_{12}+X_{22}}{2};$

A(X ₁₁，X ₂₂)，B(X ₁₂，X ₂₂)， $X_{A\_7}=\frac{X_{11}+X_{22}}{2},$ $X_{B\_7}=\frac{X_{12}+X_{22}}{2}.$

Preferably, in above-mentioned Color BTC video encoding method, write down two classes classification look C0 (R0, G0, BO) and C1 (B1), and the affiliated classified information of pixel specifically comprises for R1, G1:

Calculate distance in the class of classification back pixel, the classification look C0 of the minimum classification of distance in the record class (R0, G0, BO) and C 1 (R1, G1, B1) and the classification code stream Blockclass_bit[3:0 of four pixels].

Preferably, in above-mentioned Color BTC video encoding method, distance is 1 norm distance in the class, i.e. 2 the X (R in color space _X, G _X, B _X) and Y (R _Y, G _Y, B _Y) distance be:

|X-Y|＝|R _X-R _Y|+|G _X-G _Y|+|B _X-B _Y|。

In an embodiment of the present invention, also provide a kind of Color BTC video image decoding method, may further comprise the steps:

Obtain the classified information of vedio data piecemeal and the color classification information of the interior pixel of vedio data piecemeal;

Color value according to the color classification information reconstruction video view data of the classified information of vedio data piecemeal and pixel.

Preferably, in above-mentioned Color BTC video image decoding method, when the vedio data piecemeal is 2 * 2 piecemeal, specifically comprise according to the color value of the color classification information reconstruction video view data of the classification color of vedio data piecemeal and pixel:

According to two kinds of vedio data piecemeal classification color C0 (R0, G0, B0) and C1 (B1), and the color classification information of four pixels of vedio data piecemeal obtains the reconstruction color value of four pixels for R1, G1.

In the above-described embodiments, though what adopt is the 2*2 piecemeal, but the Color BTC algorithm synthesis that adopts during compression has been considered space level and vertical direction and R, G, correlation between three color components of B, if do not contain the sharp keen color that surpasses more than 2 kinds in this 2*2 piecemeal, just can utilize Color BTC algorithm to obtain more carefully expression by classification, overcome the compressed encoding that in the prior art YUV component is carried out different weights, can occur the problem of tangible colour cast to some sharp keen polychrome pattern.

In the above-described embodiments, owing to adopted 1bit to come the presentation code type, therefore, when judging that this 2*2 piecemeal is not gradual gradient type, when adopting Color BTC encoding and decoding, just can only represent two kinds of classification colors of this 2*2 piece with 27bit, available 4bit, 5bit, 4bit and 5bit, 5bit, 4bit represent R, G, the B component of two kinds of representative colors of this 2*2 piecemeal.

Fig. 2 shows and is used for the frame buffered data decompression method flow chart that LCD overdrives according to an embodiment of the invention, may further comprise the steps:

S202 obtains type of coding EncodeType according to block code stream;

S204 when EncodeType=1 ' b1, rebuilds above-mentioned code stream: the initial point X that obtains the 2*2 piecemeal from code stream ₁₁(R ₁₁G ₁₁B ₁₁) gradient direction Grad_dir, increment sign rgb_delta_sign[2:0], increment numerical value delta[1:0] and three color components compensation of R, G, B flag bit rgb_compflag[2:0], to initial point X ₁₁(R ₁₁G ₁₁B ₁₁) rebuild:

$\left\{\begin{array}{c}\mathrm{red}\_\mathrm{delta}=(!\mathrm{rgb}\_\mathrm{delta}\_\mathrm{sign}[2\left]\right)?\mathrm{delta}:-\mathrm{delta}\\ \mathrm{gre}\_\mathrm{delta}=(!\mathrm{rgb}\_\mathrm{delta}\_\mathrm{sign}[1\left]\right)?\mathrm{delta}:-\mathrm{delta}\\ \mathrm{blu}\_\mathrm{delta}=(!\mathrm{rgb}\_\mathrm{delta}\_\mathrm{sign}[0\left]\right)?\mathrm{delta}:-\mathrm{delta}\end{array}\right.;$

When gradient direction is that the x direction of principal axis is when being Grad_dir==1 ' b0, to other data point X in the code stream block ₁₂(R ₁₂G ₁₂B ₁₂), X ₂₁(R ₂₁G ₂₁B ₂₁) and X ₂₂(R ₂₂G ₂₂B ₂₂) rebuild respectively:

$\left\{\begin{array}{c}{R}_{12}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{12}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0)\\ B_{12}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right.;$

$\left\{\begin{array}{c}{R}_{21}=R_{11}\\ G_{21}=G_{11}\\ B_{21}=B_{11}\end{array}\right.;$

$\left\{\begin{array}{c}{R}_{22}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{22}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0)\\ B_{22}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right.;$

When gradient direction is that the y direction of principal axis is to being Grad_dir==1 ' b1, to other data point X in the code stream block ₁₂(R ₁₂G ₁₂B ₁₂), X ₂₁(R ₂₁G ₂₁B ₂₁) and X ₂₂(R ₂₂G ₂₂B ₂₂) rebuild respectively:

$\left\{\begin{array}{c}{R}_{12}=R_{11}\\ G_{12}=G_{11}\\ B_{12}=B_{11}\end{array}\right.;$

$\left\{\begin{array}{c}{R}_{21}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{21}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0)\\ B_{21}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right.;$

$\left\{\begin{array}{c}{R}_{22}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{22}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0)\\ B_{22}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right..$

In the present embodiment, the code stream of the corresponding piecemeal of former frame that the code stream of the current block of present frame and RAM outside sheet are read back compares, if code stream is identical, just think static block, do not carry out Over Drive, directly export present frame corresponding blocks data, otherwise think moving mass, output Over Drive strengthens data, because what adopt is the 2*2 piecemeal, therefore, no matter great movement velocity, also no matter the direction of motion how, all be the integral multiple of piece size half (1 pixel) on the numerical value, therefore scintillation can not occur, overcome in the prior art in order to obtain 3 times with first-class higher compression ratio, just need bigger piecemeal, yet bigger block size causes the decline of compression performance, when the former frame decompressed data that adopts big distortion is carried out OverDrive, exist in the video be not equal to block size half/during the speed motion of frame, the problem of scintillation can appear.

Preferably, in above-mentioned frame buffered data decompression method, further comprising the steps of:

When EncodeType=1 ' b0, from code stream, obtain the 4bit classified information of two classification look C0, C1 and the corresponding piecemeal of code stream;

Code stream is carried out Color BTC decoding, obtain the decoded data of piecemeal.

For Color BTC coding method, with (4,5,4), (5,5,4) represent this piece two kinds of classification look C0 (R0, G0, B0) and C1 (R1, G1 B1), represent the classified information of 4 data points in the piecemeal with 4bits.

Therefore, no matter which kind of method of employing is 32bit in the encoding code stream of assurance for the coloured image piece of 2*2, also be compression ratio 3.0.

Fig. 3 shows and is used for the circuit module figure that LCD overdrives according to an embodiment of the invention, comprising: compression module 10, sheet external memory module 20, decompression module 30, judge module 40 and look-up table means 50, wherein

Compression module 10 is used for the current block of current frame video image is compressed, and stores compressed code flow into sheet external memory module 20;

Decompression module 30, the block code that is used for the corresponding former frame video image of decompress(ion) and current block flows;

Judge module 40 is used for the block code stream of current block and the block code stream of the former frame video image of correspondence are carried out comparison, and then judges whether current block is static block;

Look-up table means 50 is used for the current block data and the corresponding former frame decompression block data of non-static block are overdrived.

In the present embodiment, current block to present frame is encoded, and compare with the code stream of the former frame corresponding blocks of reading back from sheet external memory module, if code stream is identical, just think static block, do not carry out Over Drive, directly export present frame corresponding blocks data and get final product, otherwise think moving mass, output Over Drive strengthens data.

Fig. 4 shows the frame buffer compression overdrive circuit schematic diagram that is used for LCD in accordance with a preferred embodiment of the present invention, as shown in Figure 4, the compression module that comprises current frame data, the decompression module of former frame data, the sheet external memory DDR scheduler module of packed data and decompressed data, the code stream comparison module that static block is judged, Over Drive LUT look-up table means.In (Blocki), In-1 (Blocki) are respectively the decompressed data of current frame video image corresponding blocks data and former frame corresponding blocks; The data that Iod (Blocki) obtains for OverDrive LUT, I ' is final output video data (Blocki); Coden (Blocki), Coden-1 (Blocki) are respectively the compressed bit stream of the compressed bit stream of present frame corresponding blocks and the former frame corresponding blocks that RAM reads outside sheet

Obviously, those skilled in the art should be understood that, above-mentioned each module of the present invention or each step can realize with the general calculation device, they can concentrate on the single calculation element, perhaps be distributed on the network that a plurality of calculation element forms, alternatively, they can be realized with the executable program code of calculation element, thereby, they can be stored in the storage device and carry out by calculation element, perhaps they are made into each integrated circuit modules respectively, perhaps a plurality of modules in them or step are made into the single integrated circuit module and realize.Like this, the present invention is not restricted to any specific hardware and software combination.

The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (10)

1. one kind is used for the frame buffered data compression method that LCD overdrives, it is characterized in that,

May further comprise the steps:

Video image is carried out 2 * 2 piecemeals;

R, G, the B component that calculates current block in described 2 * 2 piecemeals in the horizontal direction with the gradient of vertical direction, obtain the maximum of the gradient of described horizontal direction and vertical direction;

According to the maximum of the gradient of described horizontal direction and vertical direction, the gradient of judging described current block is that gray scale is gradual;

According to described gradient described current block is carried out the gradient incremental encoding.

2. frame buffered data compression method according to claim 1, it is characterized in that, R, G, the B color component that calculates the current block of described video image behind the piecemeal in the horizontal direction with the gradient of vertical direction, the maximum that obtains the gradient of described horizontal direction and vertical direction specifically comprises:

Calculate described current block gradient in the horizontal direction:

$\mathrm{\&Delta;R}\_x=\left\{\begin{array}{c}|R_{11}-R_{12}|\\ |R_{21}-R_{22}|\end{array}\right\},$ $\mathrm{\&Delta;G}\_x=\left\{\begin{array}{c}|G_{11}-G_{12}|\\ |G_{21}-G_{22}|\end{array}\right\},$ $\mathrm{\&Delta;B}\_x=\left\{\begin{array}{c}|B_{11}-B_{12}|\\ |B_{21}-B_{22}|\end{array}\right\};$

Calculate the gradient of described current block in vertical direction:

$\mathrm{\&Delta;R}\_y=\left\{\begin{array}{c}|R_{11}-R_{21}|\\ |R_{12}-R_{22}|\end{array}\right\},$ $\mathrm{\&Delta;G}\_y=\left\{\begin{array}{c}|G_{11}-G_{21}|\\ |G_{12}-G_{22}|\end{array}\right\},$ $\mathrm{\&Delta;B}\_y=\left\{\begin{array}{c}|B_{11}-B_{21}|\\ |B_{12}-B_{22}|\end{array}\right\};$

According to described current block in the horizontal direction with the gradient of vertical direction, obtain described current block in the horizontal direction with the maximum of the gradient of vertical direction:

$\left\{\begin{array}{c}\mathrm{\&Delta;}\_x-\max =\max \{\mathrm{\&Delta;R}\_x,\mathrm{\&Delta;G}\_x,\mathrm{\&Delta;B}\_x\}\\ \mathrm{\&Delta;}\_y\_\max =\max \{\mathrm{\&Delta;R}\_y,\mathrm{\&Delta;G}\_y,\mathrm{\&Delta;B}\_y\}\end{array}\right.;$

Wherein, described current block is expressed as $\left[\begin{array}{cc}{X}_{11}(R_{11},G_{11},B_{11})& X_{12}(R_{12},G_{12},B_{12})\\ X_{21}(R_{21},G_{21},B_{21})& X_{22}(R_{22},G_{22},B_{22})\end{array}\right],$ Horizontal direction is the x direction of principal axis, and vertical direction is the y direction of principal axis.

3. frame buffered data compression method according to claim 2 is characterized in that, whether the gradient of judging described current block is that the formula of the gradual gradient of gray scale is:

$\left\{\begin{array}{cc}\mathrm{EncodeType}=1,\mathrm{if}& 0<\mathrm{\&Delta;}\_x\_\max \&le;7,\mathrm{or}0<\mathrm{\&Delta;}\_y\_\max \&le;7\\ \mathrm{EncodeType}=0,& \mathrm{others}\end{array}\right.;$

Wherein, EncodeType=1 represents that the gradient of described current block is the gradual gradient of gray scale, adopts the gradient incremental encoding, and EncodeType=0 represents that the gradient of described current block is not the gradual gradient of gray scale, adopts Color BTC coding.

4. frame buffered data compression method according to claim 3 is characterized in that the judgment formula of the gradient direction of described current block is:

$\left\{\begin{array}{cc}\mathrm{Grad}\_\mathrm{dir}=0,\mathrm{if}& \mathrm{\&Delta;}\_x\_\max \&GreaterEqual;\mathrm{\&Delta;}\_y\_\max \\ \mathrm{Grad}\_\mathrm{dir}=1,\mathrm{if}& \mathrm{\&Delta;}\_x\_\max <\mathrm{\&Delta;}\_y\_\max \end{array}\right.;$

Wherein, Grad_dir=0 represents that the gradient direction of described current block is the x axle, and Grad_dir=1 represents that the gradient direction of described current block is the y direction of principal axis.

5. frame buffered data compression method according to claim 4, it is characterized in that, when the maximum according to the gradient of described horizontal direction and vertical direction, the gradient of judging described current block is gray scale when gradual, according to described gradient described current block is carried out the gradient incremental encoding and specifically comprises:

Adopt the 32bit code stream that described current block is carried out the gradient incremental encoding, wherein, described 32bit code stream comprises: 1bit type of coding EncodeType, 22bit piecemeal priming color C ₁₁(R ₁₁G ₁₁B ₁₁), 1bit gradient direction flag bit Grad_dir, 3bit RGB compensation flag bit rgb_compflag[2:0], 3bit gradient increase and decrease symbol position rgb_delta_sign[2:0] and 2bit gradient data position delta[1:0];

Wherein, EncodeType represents the coding method adopted, and the ColorBTC coding method is adopted in ' 0 ' expression, and gradient incremental encoding method is adopted in ' 1 ' expression; Piecemeal priming color X ₁₁(R ₁₁G ₁₁B ₁₁) represent R with 7bit, 8bit and 7bit respectively ₁₁, G ₁₁, B ₁₁Grad_dir be 0 expression level to gradient, be 1 the expression vertically to gradient; Rgb_compflag[2:0] represent whether R, G, three components of B exist gradient; Rgb-delta_sign[2:0] the gradient increment sign of expression R, G, three components of B; Delta[1:0] be gradient numerical value, scope is 0-3.

6. frame buffered data compression method according to claim 5 is characterized in that,

When described gradient direction when the x direction of principal axis is Grad_dir=0, described gradient increase and decrease symbol position rgb_delta_sign[2:0] the generation formula be:

$\left\{\begin{array}{cc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=0& \mathrm{if\&Delta;R}\_x<\mathrm{\&Delta;}\_x\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=1& \mathrm{if\&Delta;R}\_x>=\mathrm{\&Delta;}\_x\_\max /2\end{array}\right.;$

$\left\{\begin{array}{cc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=0& \mathrm{if\&Delta;G}\_x<\mathrm{\&Delta;}\_x\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=1& \mathrm{if\&Delta;G}\_x>=\mathrm{\&Delta;}\_x\_\max /2\end{array}\right.;$

$\left\{\begin{array}{cc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=0& \mathrm{if\&Delta;B}\_x<\mathrm{\&Delta;}\_x\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=1& \mathrm{if\&Delta;B}\_x>=\mathrm{\&Delta;}\_x\_\max /2\end{array}.\right.$

When described gradient direction when the x direction of principal axis is Grad_dir=0, described gradient increase and decrease symbol position rgb_delta_sign[2:0] the generation formula be:

$\left\{\begin{array}{cc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=0& \mathrm{if\&Delta;R}\_y<\mathrm{\&Delta;}\_y\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[2\right]=1& \mathrm{if\&Delta;R}\_y>=\mathrm{\&Delta;}\_y\_\max /2\end{array}\right.;$

$\left\{\begin{array}{cc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=0& \mathrm{if\&Delta;G}\_y<\mathrm{\&Delta;}\_y\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[1\right]=1& \mathrm{if\&Delta;G}\_y>=\mathrm{\&Delta;}\_y\_\max /2\end{array}\right.;$

$\left\{\begin{array}{cc}\mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=0& \mathrm{if\&Delta;B}\_y<\mathrm{\&Delta;}\_y\_\max /2\\ \mathrm{RGB}\_\mathrm{Comp}\_\mathrm{Flag}\left[0\right]=1& \mathrm{if\&Delta;B}\_y>=\mathrm{\&Delta;}\_y\_\max /2\end{array}.\right.$

7. frame buffered data compression method according to claim 1 is characterized in that, and is further comprising the steps of:

When the maximum according to the gradient of described horizontal direction and vertical direction, the gradient of judging described current block is not gray scale when gradual, according to described gradient described current block is carried out Color BTC coding.

8. one kind is used for the frame buffered data decompression method that LCD overdrives, and it is characterized in that, may further comprise the steps:

Obtain type of coding EncodeType according to block code stream;

When EncodeType=1 ' b1, from described code stream, obtain the initial point X of 2*2 piecemeal ₁₁(R ₁₁G ₁₁B ₁₁) gradient direction Grad_dir, increment sign rgb_delta_sign[2:0], increment numerical value delta[1:0] and three color components compensation of R, G, B flag bit rgb_compflag[2:0], to described initial point X ₁₁(R ₁₁G ₁₁B ₁₁) rebuild:

$\left\{\begin{array}{c}\mathrm{red}\_\mathrm{delta}=(!\mathrm{rgb}\_\mathrm{delta}\_\mathrm{sign}[2\left]\right)?\mathrm{delta}:-\mathrm{delta}\\ \mathrm{gre}\_\mathrm{delta}=(!\mathrm{rgb}\_\mathrm{delta}\_\mathrm{sign}[1\left]\right)?\mathrm{delta}:-\mathrm{delta}\\ \mathrm{blu}\_\mathrm{delta}=(!\mathrm{rgb}\_\mathrm{delta}\_\mathrm{sign}[0\left]\right)?\mathrm{delta}:-\mathrm{delta}\end{array}\right.;$

When described gradient direction is that the x direction of principal axis is when being Grad_dir==1 ' b0, to other data point X in the described code stream block ₁₂(R ₁₂G ₁₂B ₁₂), X ₂₁(R ₂₁G ₂₁B ₂₁) and X ₂₂(R ₂₂G ₂₂B ₂₂) rebuild respectively:

$\left\{\begin{array}{c}{R}_{12}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{12}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0);\\ B_{12}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right.$

$\left\{\begin{array}{c}{R}_{21}=R_{11}\\ G_{21}=G_{11}\\ B_{21}=B_{11}\end{array}\right.;$

$\left\{\begin{array}{c}{R}_{22}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{22}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0);\\ B_{22}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right.$

When described gradient direction is that the y direction of principal axis is to being Grad_dir==1 ' b1, to other data point X in the described code stream block ₁₂(R ₁₂G ₁₂B ₁₂), X ₂₁(R ₂₁G ₂₁B ₂₁) and X ₂₂(R ₂₂G ₂₂B ₂₂) rebuild respectively:

$\left\{\begin{array}{c}{R}_{12}=R_{11}\\ G_{12}=G_{11}\\ B_{12}=B_{11}\end{array}\right.;$

$\left\{\begin{array}{c}{R}_{21}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{21}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0);\\ B_{21}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right.$

$\left\{\begin{array}{c}{R}_{22}=R_{11}+(\mathrm{rgb}\_\mathrm{compflag}[2]?\mathrm{red}\_\mathrm{delta}:0)\\ G_{22}=G_{11}+(\mathrm{rgb}\_\mathrm{compflag}[1]?\mathrm{gre}\_\mathrm{delta}:0).\\ B_{22}=B_{11}+(\mathrm{rgb}\_\mathrm{compflag}[0]?\mathrm{blu}\_\mathrm{delta}:0)\end{array}\right.$

9. frame buffered data decompression method according to claim 8 is characterized in that, and is further comprising the steps of:

When EncodeType=1 ' b0, from described code stream, obtain the 4bit classified information of two classification look C0, C1 and the corresponding piecemeal of described code stream;

Described code stream is carried out Color BTC decoding, obtain the decoded data of described piecemeal.

10. one kind is used for the circuit that LCD overdrives, and it is characterized in that, comprising: compression module, sheet external memory module, decompression module, judge module and look-up table means, wherein

Described compression module is used for the current block of current frame video image is compressed, and stores compressed code flow into described external memory module;

Decompression module, the block code that is used for decompress(ion) and the corresponding former frame video image of described current block flows;

Described judge module is used for the block code stream of described current block and the block code stream of the described former frame video image of correspondence are carried out comparison, and then judges whether described current block is static block;

Described look-up table means is used for the described current block data and the corresponding described former frame decompression block data of non-static block are overdrived.

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