초록 ▼

An image compression system and method for compressing image data for transmission. Each block and corresponding sub-blocks of pixel data is subjected to a discrete cosine transform (DCT) operation. Varying levels of sub-blocks of resulting corresponding transform coefficients are selected for const

An image compression system and method for compressing image data for transmission. Each block and corresponding sub-blocks of pixel data is subjected to a discrete cosine transform (DCT) operation. Varying levels of sub-blocks of resulting corresponding transform coefficients are selected for construction into a composite transform coefficient block corresponding to each input block of pixel data. The selection of transform coefficient block size for the composite block is determined by a comparison process between transform block and sub-block coding efficiency. The composite block is variable length coded to further reduce bit count in the compressed data.

대표청구항 ▼

In an image compression system, a sub-system for generating from a block of input pixel data a corresponding composite block of discrete cosine transform (DCT) data, comprising: transform means for, receiving an input block of pixel data, performing a discrete cosine transform (DCT) operation on sai

In an image compression system, a sub-system for generating from a block of input pixel data a corresponding composite block of discrete cosine transform (DCT) data, comprising: transform means for, receiving an input block of pixel data, performing a discrete cosine transform (DCT) operation on said block of pixel data and on at least one predetermined level of constituent sub-blocks thereof, and providing corresponding block and sub-blocks of DCT coefficient values; block size assignment means for, receiving said block and each sub-block of DCT coefficient values, determining for each block and each corresponding group of sub-blocks of DCT coefficient values a bit count value corresponding to a number of bits required to respectively encode said block and each corresponding group of sub-blocks of DCT coefficient values according to a predetermined coding format, determining from said bit count values ones of said block and corresponding group of sub-blocks of DCT coefficient values requiring a lesser number of bits to encode according to said coding format, and providing a corresponding selection value; and selection means for, receiving said selection value and said block and each sub-block of DCT coefficient values, selecting ones of block and sub-blocks of DCT coefficients corresponding to said selection value, and providing an output of a corresponding composite block of DCT coefficient values formed from said selected ones of block and sub-blocks of DCT coefficient values.