Image data compression considering visual characteristic

1. An image data compression method, comprising:

determining whether image data can be compressed by a target compression ratio using one of at least one lossless compression scheme for compressing image data;

when the image data can be compressed by the target compression ratio using the one of the at least one lossless compression scheme, encoding the image data using the one of the at least one lossless compression scheme; and

when the image data cannot be compressed by the target compression ratio using the one of the at least one lossless compression scheme, encoding the image data by the target compression ratio using one of at least one lossy compression scheme,

wherein the one of the at least one lossy compression scheme is selected based on a compression error of the image data according to each of the at least one lossy compression scheme and a weighted value in each sub-pixel of a plurality of pieces of pixel data in the image data.

2. The image data compression method of claim 1 ,

wherein it is determined whether the image data can be compressed by the target compression ratio using the one of the at least one lossless compression scheme, and

wherein the one of the at least one lossless compression scheme is based on a number of pixels having identical values in a plurality of pieces of pixel data in the image data.

3. The image data compression method of claim 1 ,

wherein it is determined whether the image data can be compressed by the target compression ratio using the one of the at least one lossless compression scheme, and

wherein the one of the at least one lossless compression scheme is based on patterns of a plurality of pieces of pixel data included in the image data.

4. The image data compression method of claim 3 ,

wherein the patterns of the plurality of pieces of the pixel data represent whether values corresponding to at least a part of a specific sub-pixel of the plurality of pieces of the pixel data are identical, whether there is a sub-pixel having identical values among the plurality of pieces of the pixel data, or whether values of sub-pixels of the plurality of pieces of the pixel data are repeated regardless of a type of the values of the sub-pixels of the plurality of pieces of the pixel data.

5. The image data compression method of claim 1 , wherein encoding the image data by the target compression ratio using the one of the at least one lossy compression scheme comprises:

when the image data cannot be compressed by the target compression ratio using the one of the at least one lossless compression scheme, calculating the compression error;

calculating an estimated error of each of the at least one lossy compression scheme based on the compression error and the weighted value;

selecting the one of the at least one lossy compression scheme based on the estimated error of each of the at least one lossy compression scheme; and

encoding the image data using the one of the at least one lossy compression scheme.

6. An image data compression apparatus comprising:

at least one processor configured to:

determine whether image data can be compressed by a target compression ratio using one of at least one lossless compression scheme for compressing image data,

when the image data can be compressed by the target compression ratio using the one of the at least one lossless compression scheme, encode the image data using the one of the at least one lossless compression scheme, and

when the image data cannot be compressed by the target compression ratio using the one of the at least one lossless compression scheme, encode the image data by the target compression ratio using one of at least one lossy compression scheme,

wherein the one of the at least one lossy compression scheme is selected based on a compression error of the image data according to each of the at least one lossy compression scheme and a weighted value in each sub-pixel of a plurality of pieces of pixel data in the image data.

7. The image data compression apparatus of claim 6 ,

wherein the at least one processor is further configured to determine whether the image data can be compressed by the target compression ratio using the one of the at least one lossless compression scheme, and

wherein the one of the at least one lossless compression scheme is based on a number of pixels having identical values in a plurality of pieces of pixel data in the image data.

8. The image data compression apparatus of claim 6 ,

wherein the at least one processor is further configured to determine whether the image data can be compressed by the target compression ratio using the one of the at least one lossless compression scheme, and

wherein the one of the at least one lossless compression scheme is based on patterns of a plurality of pieces of pixel data included in the image data.

9. The image data compression apparatus of claim 8 ,

wherein the patterns of the plurality of pieces of the pixel data represent whether values corresponding to at least a part of a specific sub-pixel of the plurality of pieces of the pixel data are identical, whether there is a sub-pixel having identical values among the plurality of pieces of the pixel data, or whether values of sub-pixels of the plurality of pieces of the pixel data are repeated regardless of a type of the values of the sub-pixels of the plurality of pieces of the pixel data.

10. The image data compression apparatus of claim 6 , wherein the at least one processor is further configured to:

when the image data cannot be compressed by the target compression ratio using the one of the at least one lossless compression scheme, calculate the compression error,

calculate an estimated error of each of the at least one lossy compression scheme based on the compression error and the weighted value,

select the one of the at least one lossy compression scheme based on the estimated error of each of the at least one lossy compression scheme, and

encode the image data using the one of the at least one lossy compression scheme.