Data compression and decompression
A computer-implemented method for decompressing compressed data, the compressed data representing an n-bit decompressed data value, the compressed data comprising a first compressed subset of bits and a second compressed subset of bits, the first compressed subset representing the n−2 most significant bits of the decompressed data value and the second compressed subset representing the two least significant bits of the decompressed data value, the method comprising performing decompression of the first compressed subset using a first decompression module to determine the n−2 most significant bits of the decompressed data value; performing decompression of the second compressed subset using a second decompression module to determine the two least significant bits of the decompressed data value, the first and second decompression modules implementing different decompression schemes; and combining the determined n−2 most significant bits of the decompressed data value and the determined two least significant bits of the decompressed data value to determine the n-bit decompressed data value.
1 . A computer-implemented method for decompressing compressed data, the compressed data representing an n-bit decompressed data value, the compressed data comprising a first compressed subset of bits and a second compressed subset of bits, the first compressed subset representing the n−2 most significant bits of the decompressed data value and the second compressed subset representing the two least significant bits of the decompressed data value, the method comprising:
performing decompression of the first compressed subset using a first decompression module to determine the n−2 most significant bits of the decompressed data value;
performing decompression of the second compressed subset using a second decompression module to determine the two least significant bits of the decompressed data value, the first and second decompression modules implementing different decompression schemes; and
combining the determined n−2 most significant bits of the decompressed data value and the determined two least significant bits of the decompressed data value to determine the n-bit decompressed data value,
wherein the compressed data uses five bits to represent the two least significant bits of four decompressed data values, wherein four of the five bits comprise the second least significant bit of each decompressed data value and one of the five bits is indicative of a least significant bit for each of the four decompressed data values.
2 . The method according to claim 1 , wherein (n−2)=2 x and wherein x is an integer.
3 . The method according to claim 1 , wherein performing decompression of the first compressed subset comprises decompressing the first compressed subset by 200%.
4 . The method according to claim 1 , wherein the decompression of the first compressed subset is performed before the decompression of the second compressed subset, and wherein a result of the decompression of the first compressed subset is used in the decompression of the second compressed subset.
5 . The method according to claim 1 , wherein the decompression of the first compressed subset is performed concurrently with the decompression of the second compressed subset.
6 . The method according to claim 1 , wherein the decompressed data values represent image data.
7 . The method according to claim 1 , wherein performing decompression of the second compressed subset comprises decompressing the second compressed subset by 160%.
8 . The method according to claim 1 , wherein decompression of the compressed data representing the two least significant bits of the four decompressed data values, comprises:
retrieving, from the compressed data, the second least significant bit of each of the decompressed data values;
retrieving, from the compressed data, the one bit indicative of a least significant bit for each of the four decompressed data values; and
for each of the decompressed data values, appending the one bit indicative of the least significant bit for each of the four decompressed data values onto the respective second least significant bit of the decompressed data value.
9 . A decompression unit configured to decompress compressed data, the compressed data representing an n-bit decompressed data value, the compressed data comprising a first compressed subset of bits and a second compressed subset of bits, the first compressed subset representing the n−2 most significant bits of the uncompressed data value and the second compressed subset representing the two least significant bits of the uncompressed data value, the decompression unit comprising:
a first decompression module configured to implement a first decompression scheme to decompress the first compressed subset to determine the n−2 most significant bits of the decompressed data value;
a second decompression module configured to implement a second decompression scheme to decompress the second compressed subset to determine the two least significant bits of the decompressed data value, wherein the first and second decompression schemes are different; and
combining logic configured to combine the determined n−2 most significant bits of the decompressed data value and the determined two least significant bits of the decompressed data value to determine the n-bit decompressed data value,
wherein the compressed data uses five bits to represent the two least significant bits of four decompressed data values, wherein four of the five bits comprise the second least significant bit of each decompressed data value and one of the five bits is indicative of a least significant bit for each of the four decompressed data values.
10 . The decompression unit according to claim 9 , wherein the second decompression module decompresses the second compressed subset by 160%.
11 . The decompression unit according to claim 9 ,
wherein the second decompression module is configured to decompress the compressed data representing the two least significant bits of the four decompressed data values, by:
retrieving, from the compressed data, the second least significant bit of each of the decompressed data values;
retrieving, from the compressed data, the one bit indicative of a least significant bit for each of the four decompressed data values; and
for each of the decompressed data values, appending the one bit indicative of the least significant bit for each of the four decompressed data values onto the respective second least significant bit of the decompressed data value.
12 . The decompression unit according to claim 9 wherein the decompression unit is embodied in hardware on an integrated circuit.
13 . A non-transitory computer readable storage medium having stored thereon an integrated circuit definition dataset that, when processed in an integrated circuit manufacturing system, configures the integrated circuit manufacturing system to manufacture a decompression unit which is configured to decompress compressed data, the compressed data representing an n-bit decompressed data value, the compressed data comprising a first compressed subset of bits and a second compressed subset of bits, the first compressed subset representing the n−2 most significant bits of the uncompressed data value and the second compressed subset representing the two least significant bits of the uncompressed data value, wherein the decompression unit comprises:
a first decompression module configured to implement a first decompression scheme to decompress the first compressed subset to determine the n−2 most significant bits of the decompressed data value;
a second decompression module configured to implement a second decompression scheme to decompress the second compressed subset to determine the two least significant bits of the decompressed data value, wherein the first and second decompression schemes are different; and
combining logic configured to combine the determined n−2 most significant bits of the decompressed data value and the determined two least significant bits of the decompressed data value to determine the n-bit decompressed data value,
wherein the compressed data uses five bits to represent the two least significant bits of four decompressed data values, wherein four of the five bits comprise the second least significant bit of each decompressed data value and one of the five bits is indicative of a least significant bit for each of the four decompressed data values.