Apparatus and method for compression of image data assembled into groups

摘要

A data compression apparatus and method suitable for image data assembles pixel values into plural groups. An encoding unit sets a maximum bit plane according to a highest value in the group, and encodes the data values sequentially along the group using iteratively reduced bit plane levels until reaching a lowest bit plane or exhausting the data values in the group, to provide a compressed dataset. Examples include recording a positional index where the bit plane level is changed within each group.

主权项

1. A data compression method for image data, comprising:
receiving original image data comprising a plurality of pixel values; dividing the pixel values into a plurality of groups; for each group of the plurality of groups:
(i) setting a starting bit plane of the group according to a prominent value amongst the pixel values in the group,(ii) recording the starting bit plane of the group, and(iii) encoding one or more of the pixel values of the group using the starting bit plane of the group to provide respective encoded pixel values; and repeating the setting, recording and encoding for each group until each of the plurality of groups have been traversed, thereby providing the starting bit plane and one or more of the encoded pixel values for each group; outputting a compressed dataset comprising the encoded pixel values and the starting bit plane for each group of the plurality of groups; wherein the encoding for at least one group of the plurality of groups comprises:
providing an index respectively for each of the pixel values in the group;encoding one or more of the pixel values in the group using the starting bit plane to produce one or more respective encoded pixel values and recording the index to indicate that the one or more pixel values in the group have been encoded using the starting bit plane;iteratively changing the bit plane by levels and encoding further of the pixel values using the iteratively changed bit plane levels to produce respective encoded bit values until reaching a final bit plane or exhausting the pixel values in the group, including recording for each level the index to indicate the pixel values in the group which have been encoded in each level; andoutputting the encoded pixel values and the index recorded for the starting bit plane and the index recorded for each level to be included in the compressed dataset with respect to the at least one group.