| 摘要 |
<p>An image coding apparatus comprises a DCT unit for transforming an image signal corresponding to a target block being processed into frequency components, a quantizer for quantizing the output from the DCT unit to generate transform coefficients, a difference coefficient generator for generating difference coefficients which are differences between the transform coefficients of the target block and prediction coefficients for the target block, and an identification circuit for identifying whether or not the values of the difference coefficients are within a range of numerical values which can be expressed by N-bit fixed length codes. When the values of the difference coefficients are within the range, these difference coefficients are encoded. When at least one of the values of the difference coefficients is outside the range, the transform coefficients of the target block are encoded. Therefore, when transform coefficients, which have been obtained by compressively transforming an image signal, are encoded by using predetermined code words, intra-frame predictive coding of these transform coefficients can be reversibly carried out without degrading the coding efficiency. <IMAGE></p> |
