Method for image data compression of image block
A method for image data compression of a to-be-encoded image block includes: determining one of a plurality of preset encoding modes as an encoding mode based upon attributes of pixels of the to-be-encoded image block; and compressing image data of the to-be-encoded image block according to the encoding mode thus determined so as to obtain encoded data.
1. A method for image data compression of a to-be-encoded image block, comprising:
A) determining, using a pre-detection module, one of a plurality of preset encoding modes as an encoding mode based upon attributes of pixels of the to-be-encoded image block; and
B) compressing, using a compression processing module, image data of the to-be-encoded image block according to the encoding mode determined in step A) so as to obtain encoded data;
wherein:
in step A), the preset encoding modes include a first encoding mode and a second encoding mode, said step A) including:
A1) determining if the first encoding mode is suitable to serve as the encoding mode; and
A2) determining if the second encoding mode is suitable to serve as the encoding mode if it is determined in sub-step A1) that the first encoding mode is unsuited to serve as the encoding mode; and
one of the first encoding mode and the second encoding mode is a first edge encoding mode, and one of sub-steps A1) and A2) corresponding to the first edge encoding mode includes:
a-1) dividing the pixels of the to-be-encoded image block into two first pixel groups by applying one of a plurality of first preset masks, each of the first pixel groups including at least one of the pixels of the to-be-encoded image block;
a-2) obtaining at least one first pixel difference by:
obtaining an average pixel value of the pixels for each of the first pixel groups having at least two pixels;
calculating a first absolute difference between the average pixel value and each of the pixels for each of the first pixel groups having at least two pixels; and
obtaining the first pixel difference according to the first absolute differences obtained from each of the first pixel groups having at least two pixels;
a-3) repeating sub-steps a-1) and a-2) while applying another one of the first preset masks until all of the first preset masks have been applied; and
a-4) determining if the first edge encoding mode is suitable to serve as the encoding mode based on the first pixel differences obtained in sub-step a-2).
2. The method as claimed in claim 1 , wherein, in step A), the preset encoding modes further include a third encoding mode, said step A) further including
A3) determining if the third encoding mode is suitable to serve as the encoding mode if it is determined in sub-step A2) that the second encoding mode is unsuited to serve as the encoding mode.
3. The method as claimed in claim 2 , wherein one of the second and third encoding modes is a YUV encoding mode.
4. The method as claimed in claim 1 , wherein, in sub-step a-4), the first edge encoding mode is determined to be suitable to serve as the encoding mode when each of the first pixel differences obtained in at least one of the repetitions of sub-step a-2) is not greater than a first threshold value.
5. The method as claimed in claim 4 , wherein, when the encoding mode determined in step A) is the first edge encoding mode, said step B) includes:
encoding one of the first preset masks into a first encoding index, said one of the first preset masks conforming with a first mask condition, in that the first pixel differences associated therewith and obtained in one of the repetitions of sub-step a-2) are not greater than the first threshold value, and having a smallest one of the first pixel differences relative to other ones of the first preset masks that conform with the first mask condition; and
compressing the first pixel groups that are divided from the to-be-encoded image block by applying said one of the first preset masks associated with the first encoding index so as to obtain the encoded data.
6. The method as claimed in claim 1 , wherein, in sub-step a-2), the first pixel difference is obtained using all of red component, green component, and blue component of each of the pixels of the to-be-encoded image block in an RGB color space.
7. The method as claimed in claim 1 , wherein the first encoding mode is a uniform encoding mode, and sub-step A1) includes
i) confirming whether or not at least a leftmost data bit of each of the pixels of the to-be-encoded image block are the same; and
ii) determining the uniform encoding mode as being suitable to serve as the encoding mode when the confirmation made in step i) is affirmative.
8. The method as claimed in claim 7 , wherein, when the encoding mode determined in step A) is the uniform encoding mode, said step B) includes:
preserving complete data of one of the pixels of the to-be-encoded image block;
preserving at least one bit next to said at least the leftmost data bit for each of the other pixels of the to-be-encoded image block; and
compressing non-preserved data bits for each of the other pixels of the to-be-encoded image block.
9. The method as claimed in claim 7 , wherein, in step A), the preset encoding modes further include a third encoding mode, said step A) further including
A3) determining if the third encoding mode is suitable to serve as the encoding mode if it is determined in sub-step A2) that the second encoding mode is unsuited to serve as the encoding mode.
10. The method as claimed in claim 9 , wherein, in step A), the preset encoding modes further include a fourth encoding mode, said step A) further including
A4) determining the fourth encoding mode to serve as the encoding mode if it is determined in sub-step A3) that the third encoding mode is unsuited to serve as the encoding mode.
11. The method as claimed in claim 10 , wherein the fourth encoding mode is a YUV encoding mode.
12. A method for image data compression of a to-be-encoded image block, comprising:
A) determining, using a pre-detection module, one of a plurality of preset encoding modes as an encoding mode based upon attributes of pixels of the to-be-encoded image block; and
B) compressing, using a compression processing module, image data of the to-be-encoded image block according to the encoding mode determined in step A) so as to obtain encoded data;
wherein:
in step A), the preset encoding modes include a first encoding mode and a second encoding mode, said step A) including:
A1) determining if the first encoding mode is suitable to serve as the encoding mode; and
A2) determining if the second encoding mode is suitable to serve as the encoding mode if it is determined in sub-step A1) that the first encoding mode is unsuited to serve as the encoding mode; and
wherein one of the first encoding mode and the second encoding mode is a second edge encoding mode, and one of sub-steps A1) and A2) corresponding to the second edge encoding mode includes:
b-1) dividing the pixels of the to-be-encoded image block into three second pixel groups by applying one of a plurality of second preset masks, each of the second pixel groups including at least one of the pixels of the to-be-encoded image block;
b-2) obtaining at least one second pixel difference by:
obtaining an average pixel value of the pixels for each of the second pixel groups having at least two pixels;
calculating a second absolute difference between the average pixel value and each of the pixels for each of the second pixel groups having at least two pixels; and
obtaining the second pixel difference according to the second absolute differences obtained from each of the second pixel groups having at least two pixels;
b-3) repeating sub-steps b-1) and b-2) while applying another one of the second preset masks until all of the second preset masks have been applied; and
b-4) determining if the second edge encoding mode is suitable to serve as the encoding mode based on the second pixel differences obtained in sub-step b-2).
13. The method as claimed in claim 12 , wherein, in sub-step b-4), the second edge encoding mode is determined to be suitable to serve as the encoding mode when each of the second pixel differences obtained in at least one of the repetitions of step b-2) is not greater than a second threshold value.
14. The method as claimed in claim 13 , wherein, when the encoding mode determined in step A) is the second edge encoding mode, said step B) includes:
encoding one of the second preset masks into a second encoding index, said one of the second preset masks conforming with a second mask condition, in that the second pixel differences associated therewith and obtained in one of the repetitions of sub-step b-2) are not greater than the second threshold value, and having a smallest one of the second pixel differences relative to other ones of the second preset masks that conform with the second mask condition; and
compressing the second pixel groups that are divided from the to-be-encoded image block by applying said one of the second preset masks associated with the second encoding index so as to obtain the encoded data.
15. The method as claimed in claim 12 , wherein, in sub-step b-2), the second pixel difference is obtained using all of red component, green component, and blue component of each of the pixels of the to-be-encoded image block in an RGB color space.
16. A method for image data compression of a to-be-encoded image block, comprising:
A) determining, using a pre-detection module, one of a plurality of preset encoding modes as an encoding mode based upon attributes of pixels of the to-be-encoded image block; and
B) compressing, using a compression processing module, image data of the to-be-encoded image block according to the encoding mode determined in step A) so as to obtain encoded data;
wherein:
in step A), the preset encoding modes include a first encoding mode and a second encoding mode, said step A) including:
A1) determining if the first encoding mode is suitable to serve as the encoding mode; and
A2) determining if the second encoding mode is suitable to serve as the encoding mode if it is determined in sub-step A1) that the first encoding mode is unsuited to serve as the encoding mode;
the first encoding mode is a uniform encoding mode, and sub-step A1) includes:
i) confirming whether or not at least a leftmost data bit of each of the pixels of the to-be-encoded image block are the same; and
ii) determining the uniform encoding mode as being suitable to serve as the encoding mode when the confirmation made in step i) is affirmative;
in step A), the preset encoding modes further include a third encoding mode, said step A) further including:
A3) determining if the third encoding mode is suitable to serve as the encoding mode if it is determined in sub-step A2) that the second encoding mode is unsuited to serve as the encoding mode; and
one of the second encoding mode and the third encoding mode is a first edge encoding mode, and one of sub-steps A2) and A3) corresponding to the first edge encoding mode includes:
a-1) dividing the pixels of the to-be-encoded image block into two first pixel groups by applying one of a plurality of first preset masks, each of the first pixel groups including at least one of the pixels of the to-be-encoded image block;
a-2) obtaining at least one first pixel difference by:
obtaining an average pixel value of the pixels for each of the first pixel groups having at least two pixels;
calculating a first absolute difference between the average pixel value and each of the pixels for each of the first pixel groups having at least two pixels; and
obtaining the first pixel difference according to the first absolute differences obtained from each of the first pixel groups having at least two pixels;
a-3) repeating sub-steps a-1) and a-2) while applying another one of the first preset masks until all of the first preset masks have been applied; and
a-4) determining if the first edge encoding mode is suitable to serve as the encoding mode based on the first pixel differences obtained in sub-step a-2).
17. A method for image data compression of a to-be-encoded image block, comprising:
A) determining, using a pre-detection module, one of a plurality of preset encoding modes as an encoding mode based upon attributes of pixels of the to-be-encoded image block; and
B) compressing, using a compression processing module, image data of the to-be-encoded image block according to the encoding mode determined in step A) so as to obtain encoded data;
wherein:
in step A), the preset encoding modes include a first encoding mode and a second encoding mode, said step A) including:
A1) determining if the first encoding mode is suitable to serve as the encoding mode; and
A2) determining if the second encoding mode is suitable to serve as the encoding mode if it is determined in sub-step A1) that the first encoding mode is unsuited to serve as the encoding mode;
the first encoding mode is a uniform encoding mode, and sub-step A1) includes:
i) confirming whether or not at least a leftmost data bit of each of the pixels of the to-be-encoded image block are the same; and
ii) determining the uniform encoding mode as being suitable to serve as the encoding mode when the confirmation made in step i) is affirmative;
in step A), the preset encoding modes further include a third encoding mode, said step A) further including:
A3) determining if the third encoding mode is suitable to serve as the encoding mode if it is determined in sub-step A2) that the second encoding mode is unsuited to serve as the encoding mode; and
wherein one of the second encoding mode and the third encoding mode is a second edge encoding mode, and one of sub-steps A2) and A3) corresponding to the second edge encoding mode includes:
b-1) dividing the pixels of the to-be-encoded image block into three second pixel groups by applying one of a plurality of second preset masks, each of the second pixel groups including at least one of the pixels of the to-be-encoded image block;
b-2) obtaining at least one second pixel difference by:
obtaining an average pixel value of the pixels for each of the second pixel groups having at least two pixels;
calculating a second absolute difference between the average pixel value and each of the pixels for each of the second pixel groups having at least two pixels; and
obtaining the second pixel difference according to the second absolute differences obtained from each of the second pixel groups having at least two pixels;
b-3) repeating sub-steps b-1) and b-2) while applying another one of the second preset masks until all of the second preset masks have been applied; and
b-4) determining if the second edge encoding mode is suitable to serve as the encoding mode based on the second pixel differences obtained in sub-step b-2).