CN109326251B

CN109326251B - Image data compression method and time sequence controller

Info

Publication number: CN109326251B
Application number: CN201710647376.5A
Authority: CN
Inventors: 吴东颖
Original assignee: Himax Technologies Ltd
Current assignee: Himax Technologies Ltd
Priority date: 2017-08-01
Filing date: 2017-08-01
Publication date: 2021-02-26
Anticipated expiration: 2037-08-01
Also published as: CN109326251A

Abstract

The invention provides an image data compression method which is suitable for compressing first image data. The data block of the first image data comprises a plurality of first pixel data. The image data compression method comprises the following steps: grouping the first pixel data into a plurality of data groups, and sampling the data groups respectively to obtain a plurality of second pixel data; recording the minimum value in the first pixel data, and converting the second pixel data and the minimum value to reduce the number of bits of the second pixel data and the minimum value; calculating a plurality of differences between the second pixel data and the minimum value respectively, and taking the differences as a plurality of first quantization parameters respectively; and generating second image data according to the minimum value and the first quantization parameters, wherein the data volume of the second image data is smaller than that of the first image data.

Description

Image data compression method and time sequence controller

Technical Field

The present invention relates to data processing technologies, and more particularly, to an image data compression method and a timing controller.

Background

In order to seek higher resolution and clearer images, the current display technology is accompanied by larger memory space occupied by image data. In general, a conventional panel control device uses an image compression technique to reduce the frame memory space used by a timing controller (T-CON), thereby achieving cost reduction. That is, the application of the image compression technology to the panel control device is becoming more important. In particular, since the conventional timing controller needs to store a large amount of parameter data of an over-driving look-up table (over-drive look-up table) for an over-driving operation (over-drive) of the display panel, the timing controller needs more memory space and causes an increase in production cost. In view of the above, it is an important subject to design an efficient image data compression technique so that the timing controller can effectively reduce the amount of data stored in the frame memory.

Disclosure of Invention

The invention provides an image data compression method, which can effectively compress image data by a time schedule controller, and reduce the data volume of an over-drive look-up table (over-drive-up table) of a frame memory stored in the time schedule controller, thereby effectively increasing the data transmission rate of the time schedule controller for transmitting the image data.

The image data compression method is suitable for compressing the first image data applied to the overdrive lookup table. The data block of the first image data comprises a plurality of first pixel data. The image data compression method comprises the following steps: grouping the first pixel data into a plurality of data groups, and sampling the data groups respectively to obtain a plurality of second pixel data; recording the minimum value in the first pixel data, and converting the second pixel data and the minimum value to reduce the number of bits of the second pixel data and the minimum value; calculating a plurality of difference values between the converted second pixel data and the converted minimum value respectively, and taking the difference values as a plurality of first quantization parameters respectively; and generating second image data according to the converted minimum value and the first quantization parameters, wherein the data volume of the second image data is smaller than that of the first image data.

In an embodiment of the invention, the first image data conforms to the YUV color format, and the first pixel data includes a plurality of luminance values, a plurality of chrominance values, or a plurality of density values.

In an embodiment of the invention, the step of sampling the data groups respectively to obtain the second pixel data includes: calculating a plurality of average values of the data groups respectively as the second pixel data.

In an embodiment of the invention, the step of sampling the data groups respectively to obtain the second pixel data includes: a plurality of median values of the data groups are respectively calculated to be used as the second pixel data.

In an embodiment of the invention, the step of sampling the second pixel data according to the data groups respectively includes: determining sampling mode parameters according to the sampling modes of the second pixel data.

In an embodiment of the invention, the method for compressing image data further includes the following steps: a look-up table corresponding to the first quantization parameters is established.

In an embodiment of the invention, the method for compressing image data further includes the following steps: recording a maximum value among the first pixel data; and calculating a difference between the maximum value and the minimum value, and converting the difference to reduce the number of bits of the difference, wherein the converted difference is used as a second quantization parameter.

In an embodiment of the invention, the method for compressing image data further includes the following steps: a lookup table corresponding to the first quantization parameters is established, and an upper limit value of the lookup table is determined according to the second quantization parameter.

The timing controller of the present invention includes a receiving end circuit and a frame memory. The receiving end circuit is used for receiving first image data, and the receiving end circuit comprises an encoder, wherein a data block of the first image data comprises a plurality of first pixel data. The frame memory is coupled to the encoder. The encoder groups the first pixel data into a plurality of data groups, and samples the data groups respectively to obtain a plurality of second pixel data. The encoder records the minimum value in the first pixel data, and converts the second pixel data and the minimum value to reduce the second pixel data and the number of bits of the minimum value. The encoder calculates a plurality of differences between the converted second pixel data and the converted minimum values, respectively, and uses the differences as a plurality of first quantization parameters, respectively. The encoder generates second image data according to the minimum value and the first quantization parameters, and the data volume of the second image data is smaller than that of the first image data.

In an embodiment of the invention, the encoder calculates a plurality of average values of the data groups respectively as the second pixel data.

In an embodiment of the invention, the encoder respectively calculates a plurality of median values of the data groups as the second pixel data.

In an embodiment of the invention, the encoder determines the sampling mode parameter according to a sampling type of the second pixel data.

In an embodiment of the invention, the encoder establishes a lookup table corresponding to the first quantization parameters.

In an embodiment of the invention, the encoder records a maximum value among the first pixel data, and the encoder calculates a difference between the maximum value and the minimum value. The encoder converts the difference value to reduce the number of bits of the difference value, and uses the converted difference value as a second quantization parameter.

In an embodiment of the invention, the encoder establishes a lookup table corresponding to the first quantization parameters, and an upper limit value of the lookup table is determined according to the second quantization parameter.

Based on the above, the image data compression method of the present invention can perform the encoding operation on the pixel data of the luminance domain, the chrominance domain and the density domain of the first image data applied to the overdrive lookup table by the timing controller, so as to generate the second image data with smaller data size. Therefore, the image data compression method of the invention can effectively compress the image data by the time schedule controller, and reduce the data quantity of the overdrive lookup table for storing the overdrive (overdrive) operation applied to the display panel in the frame memory.

In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 is a schematic diagram of a timing controller according to an embodiment of the invention.

Fig. 2 is a schematic diagram of a plurality of first pixel data of a data block of first image data according to an embodiment of the invention.

FIG. 3 is a bit schematic of a first quantization parameter according to an embodiment of the invention.

FIG. 4 is a bit schematic of a second quantization parameter according to an embodiment of the invention.

Fig. 5 is a schematic diagram of a plurality of first pixel data of a data block of first image data according to another embodiment of the invention.

FIG. 6 is a bit schematic diagram of a first quantization parameter according to another embodiment of the invention.

FIG. 7 is a bit schematic diagram of a first quantization parameter according to yet another embodiment of the invention.

FIG. 8 is a bit schematic diagram of a second quantization parameter according to yet another embodiment of the invention.

FIG. 9 is a flowchart illustrating an image data compression method according to an embodiment of the invention.

Detailed Description

A number of embodiments are presented below to illustrate the invention, however the invention is not limited to the illustrated embodiments. Suitable combinations between the embodiments are also allowed.

Fig. 1 is a schematic diagram of a timing controller according to an embodiment of the invention. Referring to fig. 1, a Timing Controller 100 (TCON) includes a receiving end circuit 110(Receiver, Rx), a frame memory 120(frame memory), and a transmitting end circuit 130(Transmitter, Tx). In the present embodiment, the timing controller 100 may be used to drive a Display panel (Display panel) of a Display, wherein the Display may be a Liquid Crystal Display (LCD), but the invention is not limited thereto.

In this embodiment, the transmitting circuit 130 of the timing controller 100 may be coupled to a driving circuit to provide image data to the driving circuit, and the driving circuit drives the display panel, wherein the driving circuit includes a source driving circuit and a gate driving circuit. In the present embodiment, the timing controller 100 is configured to receive the original image data VD0 through the receiving circuit 110, wherein the original image data VD0 is image data in RGB format (Red, Green, Blue). The timing controller 100 may convert the original image data VD0 into first image data VD1 in YUV format (Chroma). Also, the timing controller 100 performs a data compression operation on the first video data VD1 to generate second video data VD 2. For example, the timing controller 100 of the embodiment can establish an overdrive look-up table (overdrive look-up table) through the compressed first image data VD1 and store the overdrive look-up table in the frame memory 120, wherein the overdrive look-up table includes a plurality of pixel data in the compressed first image data VD 1.

In the present embodiment, when the timing controller 100 drives the display panel through the driving circuit, the timing controller 100 may perform a data decompression (data decompression) operation on the second video data VD2 through the transmitting end circuit 130 to obtain decompressed first video data VD1 ', wherein the first video data VD 1' is in YUV format. The timing controller 100 converts the compressed first image data VD1 ' into restored image data VD0 ' in YUV format, and outputs the restored image data VD0 ' to the driving circuit, so that the driving circuit correspondingly outputs a plurality of overdrive voltages to drive the display panel.

Specifically, in the present embodiment, the receiving end circuit 110 may include a first data conversion circuit 111 and an encoder 112. The first data conversion circuit 111 is coupled to the encoder 112. The first data conversion circuit 111 can convert the original image data VD0 into the first image data VD1 in YUV format and provide the first image data VD1 to the encoder 112. In the present embodiment, the encoder 112 is used to perform data compression operations. That is, the encoder 112 can encode the first video data VD1 to generate the second video data VD2, wherein the amount of the second video data VD2 is smaller than that of the first video data VD 1. The encoder 112 is coupled to the frame memory 120. The encoder 112 stores the second image data VD2 in the frame memory 120.

In this embodiment, the transmitting circuit 130 may include a second data converting circuit 131 and a decoder 132. The second data conversion circuit 131 is coupled to the decoder 132. Decoder 132 is coupled to frame memory 120. In the present embodiment, the decoder 132 is configured to perform a data decompression operation. That is, when the timing controller 100 is going to drive the display panel through the driving circuit, the decoder 132 can read the second video data VD2 stored in the frame memory 120 and decode the second video data VD2 to obtain the restored first video data VD 1'. In this embodiment, the second data conversion circuit 131 can convert the restored first video data VD1 'into restored video data VD 0' in RBG format. Therefore, the timing controller 100 can output the restored image data VD 0' to the driving circuit to drive the display panel.

In the present embodiment, the encoder 112 and the decoder 132 are a combinational logic circuit, which can be used for performing an encoding operation and a decoding operation with respect to a binary (bit) parameter. In the present embodiment, the frame Memory 120 may be a Dynamic Random Access Memory (DRAM). The frame memory 120 may be used to store image data of a frame. The frame memory 120 of the present embodiment is used for storing the second video data VD2 generated after being encoded by the encoder 112. In the present embodiment, the first data conversion circuit 111 and the second data conversion circuit 131 are signal processing circuits. The first data conversion circuit 111 may be used to convert the RGB format pixel parameter signals into YUV format pixel parameter signals. The second data conversion circuit 131 may be used to convert the YUV format pixel parameter signals into RGB format pixel parameter signals.

In the present embodiment, the first video data VD1 is video data in YUV format. The first image data VD1 may include a plurality of pixel data, and the pixel data may be divided into pixel data of a Luminance (Luminance) domain, a Chrominance (Chroma) domain, and a density (Chroma) domain. In the present embodiment, the encoder 112 may perform encoding operations on pixel data in a luminance domain, a chrominance domain, and a density domain, respectively.

First, the following embodiments describe taking pixel data in a luminance domain as an example.

Fig. 2 is a schematic diagram of a plurality of first pixel data of a data block of first image data according to an embodiment of the invention. Referring to fig. 1 and 2, a data block B of the first image data VD1 may include a plurality of first pixel data Y1-Y16 representing 16 pixels. In the present embodiment, the first pixel data Y1-Y16 respectively have a plurality of luminance values, wherein the luminance values range from "0" to "255". The first pixel data Y1-Y16 can be represented by binary 8-bit parameters, respectively. In the present embodiment, the encoder 112 can group the data block B into a plurality of data groups 211-214. The data group 211 includes first pixel data Y1, Y2, Y9, Y10. The data group 212 includes first pixel data Y3, Y4, Y11, Y12. The data group 213 includes first pixel data Y5, Y6, Y13, Y14. The data group 214 includes first pixel data Y7, Y8, Y15, Y16. The encoder 112 samples the data groups 211-214 to obtain a plurality of second pixel data 221-224. That is, the encoder 112 of the present embodiment performs spatial data sampling on the first video data VD1, and the data size of the first video data VD1 is reduced to a quarter.

In the present embodiment, the encoder 112 can select an average (average) mode or a median (median) mode to sample the data groups 211-214. That is, in one embodiment, the encoder 112 may calculate a plurality of averages of the data groups 211 to 214 as a plurality of second pixel data 221 to 224, respectively. Alternatively, in another embodiment, the encoder 112 may also calculate a plurality of median values of the data groups 211-214 as a plurality of second pixel data 221-224, respectively. The second pixel data 221-224 can be a plurality of average luminance values or a plurality of median luminance values. In the present embodiment, the encoder 112 can determine the sampling mode of the second pixel data 221-224 according to the specification or display effect of the display panel, and the encoder 112 uses a binary 1-bit parameter as the sampling mode parameter to record the sampling mode of the second pixel data 221-224.

In the present embodiment, the encoder 112 selects the minimum value among the first pixel data Y1 to Y16, and records the minimum value in the form of a binary 8-bit parameter. The encoder 112 converts the second pixel data 221-224 and the minimum value to reduce the number of bits of the second pixel data 221-224 and the minimum value. For example, the encoder 112 may convert the second pixel data 221-224 and the minimum value from an 8-bit parameter to a 3-bit parameter. If the minimum value and the 8-bit parameters of the second pixel data 221-224 cannot be directly converted into 3-bit parameters, the encoder 112 selects the closest 3-bit parameter corresponding to the 8-bit parameter for representation. However, in one embodiment, the encoder 112 may also convert the second pixel data 221-224 and the minimum value from an 8-bit parameter to other lower-bit parameters, and is not limited to the above-mentioned bits.

FIG. 3 is a bit schematic of a first quantization parameter according to an embodiment of the invention. Referring to fig. 1 to 3, the binary values of the converted second pixel data 221 to 224 and the converted minimum value are exemplified as a 3-bit parameter. In this embodiment, the encoder 112 may calculate a plurality of differences between the minimum values and the second pixel data 221-224 in the form of binary 3-bit parameters, and use the differences as a plurality of first quantization parameters QP1_ 1-QP 1_4, respectively. In the present embodiment, the encoder 112 records the first quantization parameters QP1_1 to QP1_ 4. As shown in fig. 3, the first quantization parameters QP1_1 to QP1_4 representing the difference between the respective minimum values and the respective second pixel data are, for example, "000", "001", "100", and "110", respectively.

FIG. 4 is a bit schematic of a second quantization parameter according to an embodiment of the invention. Referring to fig. 1 to 4, the encoder 112 may select a maximum value (MAX) and a minimum value (MIN) among the above-described first pixel data P1 to P16, and perform the calculation of the following equation (1) to obtain the second quantization parameter QP 2. It should be noted that if the difference obtained by subtracting the maximum value and the minimum value cannot be divided by 32, which means that the 8-bit parameter cannot be directly converted into the 3-bit parameter, the encoder 112 selects the closest 3-bit parameter corresponding to the 8-bit parameter to represent it.

That is, the encoder 112 of the present embodiment may calculate the difference between the maximum value (MAX) and the minimum value (MIN) in the form of a binary 8-bit parameter, and convert the difference into a binary 3-bit parameter as the second quantization parameter QP 2. In this embodiment, the encoder 112 records the second quantization parameter QP 2. As shown in fig. 4, the second quantization parameter QP2 representing the difference between the maximum value and the minimum value may be "110", for example.

In the present embodiment, one data block B of the first image data VD1 includes luminance data of 16 pixels, and each luminance data is represented by binary 8-bit parameters (0 to 255). Therefore, the data size of one data block B of the first image data VD1 is 128 bits. However, based on the encoding operations described above with reference to the embodiment of fig. 1-4, the encoder 112 may encode a data block B of the first image data to obtain a 1-bit parameter representing the sampling pattern, an 8-bit parameter representing the minimum value, four 3-bit parameters representing the four first quantization parameters, and a 3-bit parameter representing the second quantization parameter. That is, for the pixel data in the luminance domain, one data block B corresponding to the first image data in the second image data can be compressed to 24 bits (1+8+ (3 × 4) +3 ═ 24).

In addition, in the embodiment, the encoder 112 may further establish a Look-Up Table (LUT) of a plurality of first quantization parameters QP1 corresponding to one data block B of the first video data VD1 in the second video data VD2, wherein an upper limit of the LUT is determined according to the second quantization parameter QP 2. The look-up table is shown in table 1 below.

First quantization parameter (QP1)	Parameter Value (Value)
		000	0
001	2
		010	4
011	8
		100	16
101	32
		110	64
111	128

TABLE 1

According to table 1, the parameter value "128" corresponding to the maximum value "111" of the first quantization parameter QP1 in table 1 is the result of adding the minimum value of the first pixel data Y1 to Y16 to the second quantization parameter QP2 (110+001 — 111). That is, it is assumed that the second quantization parameter QP2 is "110" and the minimum value is "001". The parameter value represented by "111" after summation is "128". Therefore, when the decoder 132 of the timing controller 100 is going to decode the second video data VD2, the first quantization parameters QP1_ 1-QP 1_4 for a data block B can determine the parameter values according to the table 1, and add the recorded minimum value to obtain a plurality of restored luminance values representing a plurality of data groups in the data block B.

Next, the following embodiment will explain an example of pixel data in a chromaticity domain or a density domain. In the present embodiment, the encoder 112 may perform the same encoding operation for the chroma domain and the density domain pixel data.

Fig. 5 is a schematic diagram of a plurality of first pixel data of a data block of first image data according to another embodiment of the invention. Referring to fig. 1 and 5, a data block B of the first image data VD1 may include a plurality of first pixel data U1/V1-U16/V16 representing 16 pixels. In the present embodiment, the first pixel data U1/V1-U16/V16 are respectively a plurality of chrominance values or a plurality of density values, wherein the chrominance values or the density values range from "0" to "255". The first pixel data U1/V1-U16/V16 can be represented by binary 8-bit parameters, respectively. In the present embodiment, the encoder 112 can group the data block B into a plurality of data groups 511-514. The data group 511 includes first pixel data U1/V1, U2/V2, U9/V9, U10/V10. The data group 512 includes first pixel data U3/V3, U4/V4, U11/V11, U12/V12. The data group 513 includes first pixel data U5/V5, U6/V6, U13/V13, U14/V14. The data group 514 includes first pixel data U7/V7, U8/V8, U15/V15, U16/V16. The encoder 112 samples the data groups 511-514 to obtain a plurality of second pixel data 521-524. That is, the encoder 112 of the present embodiment performs spatial data sampling on the first video data VD1, and the data size of the first video data VD1 is reduced to a quarter.

In the present embodiment, the encoder 112 can select an average (average) mode or a median (median) mode to sample the data groups 511-514. That is, in one embodiment, the encoder 512 may calculate a plurality of averages of the data groups 511-514 as a plurality of second pixel data 521-524, respectively. Alternatively, in another embodiment, the encoder 112 may also calculate a plurality of median values of the data groups 511-514 as a plurality of second pixel data 521-524, respectively. The second pixel data 521-524 can be a plurality of average luminance values or a plurality of median luminance values. In the embodiment, the encoder 112 can determine the sampling mode of the second pixel data 521-524 according to the specification or the display effect of the display panel, and the encoder 112 uses a binary 1-bit parameter as the sampling mode parameter to record the sampling mode of the second pixel data 521-524.

To reduce the amount of data, compared to the minimum value recorded above with respect to the luminance domain. In the present embodiment, the encoder 112 selects the minimum value among the first pixel data U1/V1-U16/V16, and records the minimum value as a binary 7-bit parameter. The encoder 112 converts the second pixel data 521-524 and the minimum value to reduce the number of bits of the second pixel data 521-524 and the minimum value. It should be noted that if the minimum 7-bit parameter or the 8-bit parameters of the second pixel data 521-524 cannot be directly converted into 3-bit parameters, the encoder 112 selects the closest 3-bit parameter corresponding to the 7-bit parameter or the 8-bit parameter for representation.

FIG. 6 is a bit schematic of a first quantization parameter according to an embodiment of the invention. Referring to fig. 1, 5 and 6, in the present embodiment, the encoder 112 may calculate a plurality of differences between the minimum values and the second pixel data 521-524 in the form of binary 3-bit parameters, and use the differences as a plurality of first quantization parameters QP1_1 'to QP1_ 4'. In this embodiment, the encoder 112 records the first quantization parameters QP1_1 'QP 1_ 4'. As shown in fig. 3, the first quantization parameters QP1_1 '-QP 1_ 4', which represent the difference between the respective minimum values and the respective second pixel data, may be "000", "001", "100", and "110", respectively.

In the present embodiment, one data block B of the first image data VD1 includes 16 pixels of chrominance data or density data, and each chrominance data or density data is represented by a binary 8-bit parameter (0-255). Therefore, the data size of one data block B of the first image data VD1 is 128 bits. However, based on the encoding operations of the embodiments of fig. 1, 5 and 6, the encoder 112 may encode a data block B of the first image data to obtain a 1-bit parameter representing the sampling pattern, a 7-bit parameter representing the minimum value, and four 3-bit parameters representing the four first quantization parameters. That is, for the pixel data in the chrominance domain or the density domain, one data block B corresponding to the first image data in the second image data can be compressed to 20 bits (1+7+ (3 × 4) ═ 20).

In addition, in the present embodiment, the encoder 112 may further establish a Look-Up Table (LUT) of a plurality of first quantization parameters QP 1' corresponding to one data block B of the first video data VD1 in the second video data VD 2. The look-up table is shown in table 2 below.

First quantization parameter (QP 1')	Parameter Value (Value)
		000	2
001	4
		010	8
011	16
		100	32
101	64
		110	128
111	256

TABLE 2

According to table 2 above, the maximum value of the first quantization parameter QP 1' in table 2 is directly set to 256. Therefore, when the decoder 132 of the timing controller 100 is going to decode the second video data VD2, the first quantization parameters QP1_1 '-QP 1_ 4' for one data block B can determine the parameter values according to the table 2, and then add the recorded minimum value to obtain a plurality of restored chrominance values or density values representing a plurality of data groups in the data block B.

Accordingly, according to the embodiments of fig. 1 to 6, the timing controller 100 can convert the first image data VD1 into the second image data VD 2. Furthermore, the total data size of the pixel data corresponding to the luminance domain, the chrominance domain and the density domain in the video data can be compressed from 384 bits (3 × 128) to 64 bits (24+20+ 20). That is, the timing controller 100 may provide a data compression ratio (compression ratio) of 6 times with respect to encoding operations of the luminance domain, the chrominance domain, and the density domain according to the embodiments of fig. 1 to 6 described above.

FIG. 7 is a bit schematic diagram of a first quantization parameter according to yet another embodiment of the invention. Referring to fig. 1, 5 and 7, in the present embodiment, the encoder 112 may also calculate a plurality of differences between the minimum values and the second pixel data 521-524 in the form of binary 2-bit parameters, and use the differences as a plurality of first quantization parameters QP1_1 "to QP1_ 4", respectively. In this embodiment, the encoder 112 records the first quantization parameters QP1_1 'QP 1_ 4'. As shown in fig. 3, the first quantization parameters QP1_1 "-QP 1_ 4", which represent the difference between the respective second pixel data and the minimum value, may be "00", "01", "10", and "11", respectively, for example.

FIG. 8 is a bit schematic diagram of a second quantization parameter according to yet another embodiment of the invention. Referring to fig. 1, 5, 7 and 8, the encoder 112 may select a maximum value (MAX) and a minimum value (MIN) of the first pixel data U1/V1-U16/V16, and perform the following calculation of equation (2) to obtain a second quantization parameter QP 2'. It should be noted that if the difference obtained by subtracting the maximum value and the minimum value cannot be evenly divided by 16, which means that the 8-bit parameter cannot be directly converted into the 4-bit parameter, the encoder 112 selects the closest 4-bit parameter corresponding to the 8-bit parameter to represent it.

That is, the encoder 112 of the present embodiment may calculate the difference between the maximum value (MAX) and the minimum value (MIN) in the form of a binary 8-bit parameter, and convert the difference into a binary 4-bit parameter as the second quantization parameter QP 2'. In this embodiment, the encoder 112 records the second quantization parameter QP 2'. As shown in fig. 8, the second quantization parameter QP 2' representing the difference between the maximum value and the minimum value may be, for example, "1100".

In the present embodiment, one data block B of the first image data VD1 includes 16 pixels of chrominance data or density data, and each chrominance data or density data is represented by a binary 8-bit parameter (0-255). Therefore, the data size of one data block B of the first image data VD1 is 128 bits. However, based on the encoding operations of the embodiments of fig. 1, 5, 7 and 8, the encoder 112 may encode a data block B of the first image data to obtain a 1-bit parameter representing the sampling pattern, a 7-bit parameter representing the minimum value, four 2-bit parameters representing four first quantization parameters, and a 4-bit parameter representing the second quantization parameter. That is, for the pixel data in the chrominance domain or the density domain, one data block B corresponding to the first image data in the second image data can be compressed to a data amount of 20 bits (7+4+1+ (4 × 2) ═ 20).

In addition, in the embodiment, the encoder 112 may further establish a Look-Up Table (LUT) of a plurality of first quantization parameters QP1_1 "-QP 1_ 4" corresponding to one of the data blocks B of the first video data VD1 in the second video data VD 2. The look-up table is shown in table 3 below.

First quantization parameter (QP 1')	Parameter Value (Value)
		00	2
01	8
		10	32
11	128

TABLE 3

According to table 3, the parameter value corresponding to the maximum value of the first quantization parameter QP1 ″ in table 3 is the result of adding the minimum value of the first pixel data U1/V1 to U16/V16 to the second quantization parameter QP2 ', wherein the second quantization parameter QP 2' and the minimum value may be converted into 8-bit parameters in advance and then added. Therefore, when the decoder 132 of the timing controller 100 is going to decode the second video data VD2, the first quantization parameters QP1_1 "-QP 1_ 4" for one data block B can determine the parameter values according to the table 3, and the minimum value recorded above is added to the parameter values, so as to obtain the restored chrominance values or density values representing the data groups in the data block B.

Accordingly, according to the embodiments of fig. 1 to 4, 7 and 8, the timing controller 100 can convert the first image data VD1 into the second image data VD 2. Furthermore, the total data size of the pixel data corresponding to the luminance domain, the chrominance domain and the density domain in the video data can be compressed from 384 bits (3 × 128) to 64 bits (24+20+ 20). That is, the timing controller 100 can provide a data compression ratio of 6 times according to the encoding operations of the embodiments of fig. 1 to 4, 7 and 8 with respect to the luminance domain, the chrominance domain and the density domain.

It should be noted that the data compression rate provided by the timing controller 100 of the present invention is not limited to the data compression result of the above-described embodiment. In one embodiment, the data compression rate provided by the timing controller 100 can be determined according to the conversion result of each image data.

FIG. 9 is a flowchart illustrating an image data compression method according to an embodiment of the invention. Referring to fig. 1 and fig. 9, the image data compression method of the present embodiment is at least suitable for the timing controller 100 of fig. 1. The image data compression method of the present embodiment may encode the first image data by the encoder 112 of the timing controller 100, and one data block of the first image data includes a plurality of first pixel data. In step S910, the encoder 112 groups the first pixel data into a plurality of data groups, and samples the data groups to obtain a plurality of second pixel data. In step S920, the encoder 112 records the minimum value of the first pixel data, and converts the second pixel data and the minimum value to reduce the number of bits of the second pixel data and the minimum value. In step S930, the encoder 112 calculates a plurality of differences between the converted second pixel data and the converted minimum values, respectively, and uses the differences as a plurality of first quantization parameters, respectively. In step S940, the encoder 112 generates second image data according to the converted minimum value and the first quantization parameters, and the data amount of the second image data is smaller than that of the first image data. Accordingly, the image data compression method of the present embodiment may encode pixel parameters of a plurality of luminance values, a plurality of chrominance values, or a plurality of density values in the first image data to obtain corresponding second image data, wherein the second image data includes the transformed minimum value and a plurality of first quantization parameters. The image data compression method of the embodiment can effectively compress the data volume of the first image data.

In addition, the related device characteristics, the parameter calculation method and the encoding method of the image data compression method of the present embodiment can obtain sufficient teaching, suggestion and implementation descriptions from the above description of the embodiments of fig. 1 to 8, and therefore, are not repeated herein.

In summary, the image data compression method of the present invention can effectively compress the image data by the timing controller, and can provide a data compression ratio of 6 times, for example, to reduce the amount of data stored in the frame memory. The image data compression method of the invention can respectively carry out coding operation on the pixel data of a brightness domain, a chroma domain and a concentration domain in the first image data by the time schedule controller so as to generate the second image data with smaller data quantity. Therefore, the image data compression method of the invention can effectively reduce the data quantity transmitted by the time schedule controller and effectively increase the transmission speed by the time schedule controller.

Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. An image data compression method is suitable for compressing first image data applied to an overdrive lookup table, wherein a data block of the first image data comprises a plurality of first pixel data, and the method comprises the following steps:

grouping the first pixel data into a plurality of data groups, and sampling the data groups respectively to obtain a plurality of second pixel data;

recording a minimum value of the plurality of first pixel data, and converting the plurality of second pixel data and the minimum value to reduce the number of bits of the plurality of second pixel data and the minimum value;

calculating a plurality of difference values between the converted second pixel data and the converted minimum value respectively, and taking the plurality of difference values as a plurality of first quantization parameters respectively; and

and generating second image data according to the converted minimum value and the plurality of first quantization parameters, wherein the data volume of the second image data is smaller than that of the first image data.

2. The method of claim 1, wherein the first image data conforms to YUV color format, and the first pixel data are a plurality of luminance values, a plurality of chrominance values, or a plurality of density values.

3. The method of claim 1, wherein the step of sampling the data groups to obtain the second pixel data comprises:

calculating a plurality of average values of the plurality of data groups respectively as the plurality of second pixel data.

4. The method of claim 1, wherein the step of sampling the data groups to obtain the second pixel data comprises:

and respectively calculating a plurality of median values of the plurality of data groups to be used as the plurality of second pixel data.

5. The method of claim 1, wherein the step of sampling the data groups to obtain the second pixel data comprises:

determining a sampling mode parameter according to the sampling mode of the plurality of second pixel data.

6. The method of compressing video data according to claim 1, further comprising:

a look-up table corresponding to the plurality of first quantization parameters is established.

7. The method of compressing video data according to claim 1, further comprising:

recording a maximum value among the plurality of first pixel data; and

calculating a difference between the maximum value and the minimum value, and converting the difference to reduce the number of bits of the difference, wherein the converted difference is used as a second quantization parameter.

8. The method of compressing image data according to claim 7, further comprising:

establishing a lookup table corresponding to the first quantization parameters, and determining an upper limit value of the lookup table according to the second quantization parameter.

9. A timing controller, comprising:

a receiving end circuit, configured to receive first image data, wherein a data block of the first image data includes a plurality of first pixel data; and

a frame memory coupled to the encoder,

wherein the encoder groups the first pixel data into a plurality of data groups and samples the data groups to obtain a plurality of second pixel data,

wherein the encoder records a minimum value of the plurality of first pixel data and converts the plurality of second pixel data and the minimum value to reduce the number of bits of the plurality of second pixel data and the minimum value,

wherein the encoder calculates a plurality of difference values between the converted second pixel data and the converted minimum value, respectively, and uses the plurality of difference values as a plurality of first quantization parameters, respectively,

the encoder generates second image data according to the minimum value and the first quantization parameters, and the data size of the second image data is smaller than that of the first image data.

10. The timing controller of claim 9, wherein the first image data conforms to YUV color format, and the plurality of first pixel data are a plurality of luminance values, a plurality of chrominance values, or a plurality of density values.

11. The timing controller of claim 9, wherein the encoder calculates a plurality of averages of the plurality of data groups as the plurality of second pixel data, respectively.

12. The timing controller of claim 9, wherein the encoder calculates a plurality of median values of the plurality of data groups as the plurality of second pixel data, respectively.

13. The timing controller of claim 9, wherein the encoder determines a sampling mode parameter according to a sampling type of the second pixel data.

14. The timing controller of claim 9, wherein the encoder establishes a look-up table corresponding to the plurality of first quantization parameters.

15. The timing controller of claim 9, wherein the encoder records a maximum value among the plurality of first pixel data, and calculates a difference value of the maximum value and the minimum value,

wherein the encoder converts the difference value to reduce the number of bits of the difference value, and uses the converted difference value as a second quantization parameter.

16. The timing controller of claim 15, wherein the encoder establishes a lookup table corresponding to the plurality of first quantization parameters, and an upper limit value of the lookup table is determined according to the second quantization parameter.