Exploiting redundant bit combinations in a compressed representation of an image

A system, comprising:

• a non-transitory memory storage of a receiving device comprising instructions;
• and
• one or more processors of the receiving device in communication with the memory, wherein the one or more processors execute the instructions to:
• compress a block of an image using a default block compression scheme to generate a first compressed representation of the block, the default block compression scheme configured to generate a compressed representation of a given block that includes a first set of bits representing a first value and a second set of bits representing a second value;
• compute a first error for the first compressed representation of the block;
• compress the block of the image using an auxiliary block compression scheme to generate a second compressed representation of the block, the auxiliary block compression scheme configured to exploit a plurality of redundant bit combinations supported by the default block compression scheme, each redundant bit combination of the plurality of redundant bit combinations occurring when a difference between the first set of bits in the compressed representation and the second set of bits in the compressed representation is between 0 and a defined threshold, wherein the defined threshold is greater than 0;
• compute a second error for the second compressed representation of the block;
• select between the first compressed representation of the block and the second compressed representation of the block, based on the first error and the second error, to result in a selected compressed representation of the block;
• and
• store the selected compressed representation of the block in a compressed representation of the image;
• wherein the auxiliary block compression scheme is configured by:
• detecting the plurality of redundant bit combinations in two subsets including a first subset of redundant bit combinations where c1−c0<=2n−2 and c0<2m−(2n−2) and a second subset of redundant bit combinations where c0>=2m−(2n−2), where c0 is the first set of bits, c1 is the second set of bits, m is a number of bits in the first value and the second value, and n is a number of per-pixel index bits,
• enumerating the redundant bit combinations in the first subset of redundant bit combinations and the redundant bit combinations in the second subset of redundant bit combinations,
• computing a number of the plurality of redundant bit combinations supported by the default block compression scheme based on the enumerating,
• configuring the auxiliary block compression scheme to use the number when generating the second compressed representation of the block.

A non-transitory computer-readable media storing computer instructions which when executed by one or more processors of a receiving device cause the receiving device to:

• compress a block of an image using a default block compression scheme to generate a first compressed representation of the block, the default block compression scheme configured to generate a compressed representation of a given block that includes a first set of bits representing a first value and a second set of bits representing a second value;
• compute a first error for the first compressed representation of the block;
• compress the block of the image using an auxiliary block compression scheme to generate a second compressed representation of the block, the auxiliary block compression scheme configured to exploit a plurality of redundant bit combinations supported by the default block compression scheme, each redundant bit combination of the plurality of redundant bit combinations occurring when a difference between the first set of bits in the compressed representation and the second set of bits in the compressed representation is between 0 and a defined threshold, wherein the defined threshold is greater than 0;
• compute a second error for the second compressed representation of the block;
• select between the first compressed representation of the block and the second compressed representation of the block, based on the first error and the second error, to result in a selected compressed representation of the block;
• and
• store the selected compressed representation of the block in a compressed representation of the image;
• wherein the auxiliary block compression scheme is configured by:
• detecting the plurality of redundant bit combinations in two subsets including a first subset of redundant bit combinations where c1−c0<=2n−2 and c0<2m−(2n−2) and a second subset of redundant bit combinations where c0>=2m−(2n−2), where c0 is the first set of bits, c1 is the second set of bits, m is a number of bits in the first value and the second value, and n is a number of per-pixel index bits,
• enumerating the redundant bit combinations in the first subset of redundant bit combinations and the redundant bit combinations in the second subset of redundant bit combinations,
• computing a number of the plurality of redundant bit combinations supported by the default block compression scheme based on the enumerating,
• configuring the auxiliary block compression scheme to use the number when generating the second compressed representation of the block.

A method, comprising:

• at a device:
• selecting, for decompression, a compressed representation of a block of an image stored in a compressed representation of the image;
• determining, from bits in the compressed representation of the block, which block compression scheme was used to create the compressed representation of the block, the block compression scheme being determined from among:
• a default block compression scheme configured to generate a particular compressed representation of a given block that includes a first set of bits representing a first value and a second set of bits representing a second value, and
• an auxiliary block compression scheme configured to exploit a plurality of redundant bit combinations supported by the default block compression scheme, each redundant bit combination of the plurality of redundant bit combinations occurring when a difference between the first set of bits in the particular compressed representation and the second set of bits in the particular compressed representation is between 0 and a defined threshold, wherein the defined threshold is greater than 0;
• and
• decompressing the compressed representation of the block using a block decompression scheme corresponding to the determined block compression scheme;
• wherein the auxiliary block compression scheme is configured by:
• detecting the plurality of redundant bit combinations in two subsets including a first subset of redundant bit combinations where c1−c0<=2n−2 and c0<2m−(2n−2) and a second subset of redundant bit combinations where c0>=2m−(2n−2), where c0 is the first set of bits, c1 is the second set of bits, m is a number of bits in the first value and the second value, and n is a number of per-pixel index bits,
• enumerating the redundant bit combinations in the first subset of redundant bit combinations and the redundant bit combinations in the second subset of redundant bit combinations,
• computing a number of the plurality of redundant bit combinations supported by the default block compression scheme based on the enumerating,
• configuring the auxiliary block compression scheme to use the number when generating the second compressed representation of the block.