Limbach & Limbach LLP
Image data compression method and apparatus with pre-processing to compensate for the blocky effect
 A method and apparatus in which image data are pre-processed before undergoing block-basis image compression to compensate at least partially for the artifact known as the blocky effect that would otherwise be apparent upon decoding of the compressed data. The input data are pre-processed by combining error-correction data therewith, before block-basis compression is performed thereon. Blocky effect errors introduced during block-basis compression (e.g., standard MPEG compression) of the pre-processed input data and subsequent decoding will cancel (at least partially) the error-correction data, thereby compensating (at least partially) for the blocky effect that would otherwise occur without pre-processing. The error-correction data can be generated by performing block-basis compression on input data (performing a discrete cosine or other transform thereon and then quantizing the transformed data); then, performing the inverse transform on the quantized data to generate test data; and then, computing the difference between the input and test data to generate the error-correction data. In preferred embodiments, the apparatus of the invention is a pre-processor which combines error-correction data with input image data to generate pre-processed data for subsequent compression and decoding with reduced blocky effect. In other embodiments, the apparatus also includes a block-basis image compressor including a forward transformer for transforming the pre-processed data, and a quantizer for quantizing the transformed data to generate compressed image data. 
Sony Corportion Sony Electronics, Inc.
H H
H04N H04N
inventional inventional
Ching-Fang Teruyoshi Masao
Chang Komuro Mizutani