| 摘要 |
PROBLEM TO BE SOLVED: To prevent image quality from being deteriorated in the case of rotation/mirror display conversion by applying rotation conversion consisting of combination of rotation processing, horizontal mirror processing and vertical mirror processing to encoded image data subject to entropy decoding. SOLUTION: The JPEG data to be converted are Huffman-decoded to obtain a quantized DCT coefficient block (S101). Then the encoded quantized DCT coefficient block is inversely quantized (S102). Rotation mirror display conversion is conducted for each decoded DCT coefficient block (S103). The processing sequence of the converted blocks is rearranged in matching with the rotation mirror display conversion (S104). Then each DCT coefficient block is quantized (S105) to obtain the quantized coefficient block. Then finally Huffman coding is applied to each quantized DCT coefficient block (S106). Since no orthogonal transformation is used for the processing procedure, the processing is conducted at a high speed, and since no error in the floating point arithmetic operation by the orthogonal transformation is caused, the image quality is prevented from being deteriorated. |
