CN2583731Y - Image data compression device - Google Patents

Abstract

The utility model relates to an image data compression device. The image data compression device comprises a first data buffer, a first coder and a second coder, wherein, the first data buffer is connected with an image picking up device in a signal mode and stores a first data byte and a second data byte which are sent out by the image picking up device; the first coder is connected with the first data buffer in the signal mode; the first coder carries out comparison operation of the second data byte and the first data byte, obtains a difference value which is signified by m bits and outputs the difference value; the second coder is connected with the first coder and a frame buffer in the signal mode; the second coder codes the difference value to obtain a data code which is used for reducing and outputs the data code to the frame buffer to be stored. The utility model is capable of rapidly completing the actions of compression and decompression without additional complicated circuits and is very suitable for being applied for a system structure with the real time compression and the decompression.

Description

The image data compression set

Technical field

The utility model relates to a kind of image data compression set, and finger is applied to the image data compression set in the computer system especially.

Background technology

See also Fig. 1, be personal computer architecture synoptic diagram commonly used at present, its core partly mainly is made of with South Bridge chip 12 microprocessor 10, north bridge chips 11, and Installed System Memory 13 utilizes a rambus to be connected to north bridge chips 11, sees through a perimeter component connecting interface bus (PCI) or draws as for 14 of video cards and quicken port (AGP) bus and be connected with north bridge chips 11.Wherein video card 14 consists predominantly of a drawing chip 141 and a region memory (local memory) 142.

The region memory that video card 14 is comprised (local memory) 142 uses as frame buffer (framebuffer) usually, when the image data output unit, for example the simulating signal that produced of TV frequency variator 15 (TV tuner) is sent into video card 14, sending into drawing chip 141 after the analog to digital converter 143 on it converts a digital image data to handles, and drawing chip 141 just writes this digital image data in the frame buffer (frame buffer) that is defined in the region memory (local memory) 142, so that these image datas can be read and play.Or, system also can with digital image data with an internal memory direct access move (DMA) write direct and deposit in the Installed System Memory 13, change into archives and deposit in order to further will be stored in the Installed System Memory 13 digital image data to a non-volatile memory unit (for example hard disk among the figure 16).

But because the image data amount is all very huge usually, therefore carrying out above-mentioned image capture action or image playback action, need take the frequency range of a large amount of memory headrooms and access frequency range thereof, perimeter component connecting interface bus or the acceleration port bus of drawing, or even the storage area of non-volatile memory unit.So, cross the decline that the big data quantity transmission will cause the personal computer overall efficiency.

See also Fig. 2, it is one to have contract personal computer system's block diagram of function of data compression/decompression, and this computer system consists predominantly of microprocessor 20, north bridge chips 21, South Bridge chip 22, Installed System Memory 23, image capture unit 243 and image player 244. and when an image capture unit 243 (such as the TV signal decoder (TV decoder) that the anolog TV signals such as NTSC or PAL is converted to a data signal (for example YUV422)) acquisition one digital image data and when sending into the drawing chip 241 that is arranged on the video card 24 and processing; Be located at the digital image data that the data compression device in the drawing chip 241 2411 is exported this image capture unit 243 in the native system (for example YUV422) and compress and obtain compressing image data and be stored in the one frame buffer, and this frame buffer is defined in the region memory 242 that is arranged on the video card 24. When needs were play immediately, data decompression compression apparatus 2412 just decompressed stored these compressing image data of this frame buffer and returns back to this digital image data, transferred to this image player 244 again and played back on a display 27.

In addition, when system's desire will be stored in compressing image data storing in the frame buffer when becoming image archives, just can utilize internal memory direct access action that these compressing image data are write direct in this Installed System Memory 23, and then unloading is to hard disk 26.Therefore, when system desires to carry out the playback action of these image archives, just from hard disk 26 with this image archives unloading to Installed System Memory 23, utilize this internal memory direct access action that these compressing image data are moved in this frame buffer subsequently, and data decompression compression apparatus 2412 just can decompress these compressing image data and return back to this digital image data, and then further offers image player 244 and play back in display 27.

But, static image compress technique commonly used and being not suitable for is applied in the system architecture that above-mentioned needs reach Real Time Compression and decompression, dynamic image compress technique commonly used then can increase the complexity of circuit, and how to develop the compression/de-compression technology that a suitable said system structure, be fundamental purpose of the present utility model.

Summary of the invention

The purpose of this utility model is for a kind of image data compression set is provided,

The purpose of this utility model can realize by following measure:

A kind of image data compression set, be arranged in the image accelerator, this image accelerator includes an image capture unit and one frame buffer, this data compression device comprises: one first data buffer, signal is connected in this image capture unit, and it will be stored by one first data byte and one second data byte that this image capture unit is sent; One first scrambler, signal are connected in this first data buffer, and it compares computing with this second data byte and this first data byte and obtains a difference of representing with m bit and exported; One second scrambler, signal is connected in this first scrambler and this frame buffer, it is encoded to this difference and obtains a reduction and export to numeric data code and to deposit in this frame buffer, wherein when the absolute value of this difference during less than one first threshold value, then utilize a variable length code method this difference is encoded and to convert to this reduction of representing less than m bit numeric data code, and when the absolute value of this difference more than or equal to this first threshold value during smaller or equal to one second threshold value, then utilize a fixed-length code (FLC) method that this difference is encoded and convert this reduction of representing with m bit numeric data code to, and, then directly this second data byte is compressed into this reduction numeric data code when the absolute value of this difference during greater than this second threshold value.

Described data byte is represented the brightness value or the chroma value of two adjacent pixels.

Described image data compression set also comprises an image data decompressing device, and its signal is connected to this frame buffer, and this image data decompressing device comprises: one second data buffer, and it stores this first data byte of having finished reconstruction; One code translator, signal is connected in this frame buffer and this second data buffer, its this reduction that this frame buffer is exported is deciphered with numeric data code and is obtained this difference, wherein when this reduction meets a first condition with the Q-character in the numeric data code, utilize a variable length code table of comparisons to reduce and be reduced into a difference with numeric data code, and with this difference and this finished the first data byte addition of reconstruction and decompress(ion) is withdrawn one second data byte and this second data buffer of Hui Cunzhi, and when this Q-character met a second condition, this reduction of part that directly will remove this Q-character was with numeric data code decompress(ion) withdraw this second data byte and this second data buffer of Hui Cunzhi.

This first condition is 1 for this Q-character.

This second condition is 0 for this Q-character.

Be divided by two and insert this Q-character that meets this second condition with this difference with the action of numeric data code directly in the said apparatus with being compressed into reduction in this second data byte.

This first scrambler is a differentiated pulse coding modulator in the said apparatus.

This second scrambler is a variable length coder in the said apparatus.

Description of drawings

Fig. 1 is a personal computer architecture synoptic diagram commonly used at present.

Fig. 2 has contract personal computer system's block diagram of function of data compression/decompression.

Fig. 3 is a preferred embodiment block diagram of data compression device of the present utility model.

Fig. 4 is the variable length code table of comparisons of preferred embodiment of the present utility model.

Fig. 5 is another preferred embodiment block schematic diagram of data decompression compression apparatus of the present utility model.

Fig. 6 (a) is (b): the modes of emplacement synoptic diagram that is respectively the compressing image data in conventional means and the utility model preferred embodiment.

Embodiment

See also Fig. 3, it has contract this data compression device 2411 among the personal computer system of function of data compression/decompression and develops the preferred embodiment block diagram that at above-mentioned for the utility model, for convenience of description, below with the brightness value Y in the YUV422 form be example (certainly, chroma value U, the also available same way as of V is carried out), Y (i) wherein, 8 continuous 2 brightness values of same row in Y (i+1) image that to be representative exported by image capture unit 243, it is placed in earlier in first data buffer 30, pass through the processing of first scrambler of being finished by differentiated pulse coding modulator 31, and then draw Y (i), the difference of Y (i+1), second scrambler of being finished via variable length coder 32 is again encoded subsequently, and then reaches the purpose of compression.

And relevant variable length decoding method can be with reference to the table of comparisons listed among the figure 4, and wherein D (i) represents the absolute value of Y (i), 2 differences of Y (i+1), promptly D (i)=| Y (i+1)-Y (i) |.Yet, the back is found by statistics, usually the color-values (comprising brightness value and chroma value) of neighbor pixel is neither has a too violent variation, so D (i) value that differentiated pulse coding modulator 31 is produced drops on the less part of numerical value mostly, therefore, for reaching the figure place that reduces after encoding, to become reduction numeric data code (wherein last position s represents sign) less than D (i) the value code conversion of one first threshold value (this example is 8) less than 8 positions, and during less than one second threshold value (this example is 15), then only can convert the reduction numeric data code of 8 positions more than or equal to this first threshold value (this example is 8) to when D (i) value.As for when D (i) value during, then directly 7 higher among the Y (i+1) bit data right shifts are inserted 0 (being about to Y (i+1) divided by two) to 7 lower bit data and in most significant digit, and then form the reduction numeric data code greater than this second threshold value.

In sum, because D (i) value that differentiated pulse coding modulator 31 is produced drops on the less part of numerical value mostly, so the utility model will represent with numeric data code with the reduction of less figure place less than 8 D (i) value, and then reach the purpose of data compression.Then represent with numeric data code less than 15 D (i) value more than or equal to 8 with the reduction of identical figure place.As for when producing, then directly Y (i+1) is encoded divided by 2 greater than 15 D (i) value.See through the formed reduction of above-mentioned compression step and can be stored into numeric data code in the frame buffer 33 that is defined in the region memory, just can reach data compression thus and reduce the purpose that takies a large amount of memory headrooms and access frequency range thereof.

In addition, when system's desire will be stored in compressing image data storing in the frame buffer when becoming image archives, can utilize internal memory direct access action that these compressing image data are write direct in this Installed System Memory equally, and then unloading is to hard disk.Therefore, when system desires to carry out the playback action of these image archives, just from hard disk with this image archives unloading to Installed System Memory, utilize this internal memory direct access action that these compressing image data are moved in this frame buffer subsequently, and data decompression compression apparatus 2412 just can decompress these compressing image data and return back to this digital image data, and then further offers image player and play back in display.

And when needs are play, data decompression compression apparatus 2412 as shown in Figure 5 just can decompress these frame buffer 33 stored these reduction and revert back to this digital image data with numeric data code, and then transfers to this image player again and play back on a display.Wherein this data decompression compression apparatus 2412 mainly is made of one second data buffer 50 and a code translator 51.This second data buffer 50 in order to deposit decompress the institute rebuild time Y (i) ', and code translator 51 is judged with the Q-character in the numeric data code (most significant digit that this is routine) according to the reduction of being taken out by frame buffer 33 again, when Q-character meets first condition (this example is that most significant digit is 1), just can utilize the variable length code table of comparisons shown in Figure 4 to reduce and be reduced into the difference that comprises sign, and this difference and this have been finished Y (the i) ' addition of reconstruction and decompress(ion) is withdrawn in a Y (i+1) ' and this second data buffer 50 of Hui Cunzhi with numeric data code.But when this Q-character meets a second condition (this example is that most significant digit is 0), just must return this Y (i+1) ' after can directly this reduction of part of removing this Q-character being multiply by 2 with numeric data code, though the Y (i+1) ' that rebuilds this moment and original Y (i+1) might have error (in this example for being not more than 1), but Y (i) in the time of therefore, 2 differences of Y (i+1) are very big, though therefore the image of rebuilding slightly distortion also be difficult for being discovered.

But because of the image data after the compression, brightness (the Luma of its each pixel, Y), chroma (Chroma, U and V) figure place might be different, and place image data and improper with usual way (seeing shown in Fig. 6 (a)), and be convenient these image datas that when image is play, reads, the utility model has still been made the modes of emplacement of image data and has been changed (seeing shown in Fig. 6 (b)), it is with brightness (Luma, Y) data, chroma (Chroma, U and V) data are placed on different internal memory register mode areas respectively, this kind location mode can make things convenient for the realization of pipeline in the hardware circuit (pineline) structure, because under the structure of YUV422, the sampling frequency of brightness data Y is the twice of chroma data U or V, available two groups of code translators in decompression process, one group brightness data Y deciphered, each clock pulse decodable code goes out a brightness data, and another group is deciphered chroma data U or V, and each clock pulse decodable code goes out a chroma data U or V.Thus, each code translator only needs to decipher out data in each clock pulse and can restore complete pixel data Y, U and V.And compression handle a row pixel number according to after, respectively its length data is write file Head Section (Y Header and CHeader), and the information of this file Head Section is used can be convenient to decompress in action or the internal memory direct access action (DMA) reading of data the time, with this example, available 0000-0000 to 0000-0111 comes to use as the coding of these specific file headers.

And by above-mentioned narration as can be known, the utility model does not need extra complicated circuit just can finish compression and the action that decompresses apace, is fit to very much be applied in the system architecture of Real Time Compression and decompression.

Claims (8)

1, a kind of image data compression set is arranged in the image accelerator, and this image accelerator includes an image capture unit and one frame buffer, it is characterized in that this data compression device also comprises:

One first data buffer, signal is connected in this image capture unit, and one first data byte and one second data byte exported by this image capture unit are stored in this first data buffer;

One compares computing with this second data byte and this first data byte and obtains a difference of representing with m bit and first scrambler of being exported, and signal is connected in this first data buffer; And

A pair of above-mentioned difference is encoded and is obtained second scrambler that a reduction is exported with numeric data code, and signal is connected in this first scrambler and this frame buffer.

2, image data compression set as claimed in claim 1 is characterized in that described data byte represents the brightness value or the chroma value of two adjacent pixels.

3, image data compression set as claimed in claim 1 is characterized in that also comprising an image data decompressing device, and its signal is connected to this frame buffer, and this image data decompressing device comprises:

One stores second data buffer of this first data byte of having finished reconstruction; And

This reduction that a pair of this frame buffer is exported is deciphered with numeric data code and is obtained the code translator of this difference, and signal is connected in this frame buffer and this second data buffer; When this reduction meets a first condition with the Q-character in the numeric data code, this code translator utilizes a variable length code table of comparisons to reduce and is reduced into a difference with numeric data code, and with this difference and this finished the first data byte addition of reconstruction and decompress(ion) is withdrawn one second data byte and this second data buffer of Hui Cunzhi, and when this Q-character met a second condition, this reduction of part that this code translator directly will be removed this Q-character was with numeric data code decompress(ion) withdraw this second data byte and this second data buffer of Hui Cunzhi.

4, image data compression set as claimed in claim 3 is characterized in that this first condition is 1 for this Q-character.

5, image data compression set as claimed in claim 3 is characterized in that this second condition is 0 for this Q-character.

6, image data compression set as claimed in claim 3 is characterized in that directly with being compressed into the action of reduction with numeric data code in this second data byte be divided by two and insert this Q-character that meets this second condition with this difference.

7, image data compression set as claimed in claim 1 is characterized in that this first scrambler is a differentiated pulse coding modulator.

8, image data compression set as claimed in claim 1 is characterized in that this second scrambler is a variable length coder.

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