Patent attributes
A method and decompression unit for performing decompression to determine image element values from compressed data representing a block of image element values each comprising one or more data values relating to a respective one or more channels. An indication of an origin value for each of the channels is read from the compressed data. For each of the channels, an indication of a first number of bits for representing difference values between the data values and the origin value for the channel is read from the compressed data. For each of the one or more channels, a second number of bits is obtained, wherein representations of the difference values for each of the channels are included in the compressed data using the second number of bits for that channel. The obtained second numbers of bits for the respective channels are used to read the representations of the difference values for the image element values being decompressed from the compressed data. Based on the representations of the difference values read from the compressed data, for each of the channels and for each of the image element values being decompressed, a difference value is determined in accordance with the first number of bits for the channel. For each of the one or more channels, the data value relating to the channel for each of the image element values being decompressed is determined using: (i) the origin value for the channel, and (ii) the determined difference value for the channel for the image element value.
