Patent ID: 11915455
Assignee: IMAGINATION TECHNOLOGIES LIMITED
Field: Audio-visual technology (Electrical engineering)
Classification: CPC G  H | IPC G

Claim 0:
1. A method of compressing a block of image data, the block of image data comprising a plurality of image element values, each image element value being formed of at least a first value such that the block of image data comprises a two-dimensional block of first values, the two-dimensional block of first values being divided into at least one size of sub-blocks of first values, the method comprising:
dynamically selecting which of the two-dimensional block of first values and the sub-blocks of first values are to be stored in compressed format;
forming a compressed block for the block of image data by:
forming a header of the compressed block comprising:
information for the two-dimensional block of first values indicating whether the two-dimensional block of first values is in compressed format,
information for each sub-block of first values indicating whether that sub-block of first values is in compressed format, and
for each block and sub-block of first values that is in compressed format, common base information that is common to the first values of that block or sub-block; and

forming a body of the compressed block comprising:
for each first value that forms part of a block or sub-block of first values that is in compressed format, a fixed-length parameter for that first value, that is zero, one or more than one bits in length, that first value being obtainable from the common base information for that block or sub-block and the fixed-length parameter for that first value, and,
for each first value that does not form part of a block- or sub-block of first values that is in compressed format, that first value.