IMAGE CODER, IMAGE CODING METHOD, IMAGE TRANSMITTER, IMAGE TRANSMISSION METHOD AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To prevent deterioration in image quality of a decoded image due to the change in a quantization step of a macro block caused by rate control. SOLUTION: A quantization circuit 15 quantizes a discrete cosine transformation DCT coefficient outputted from a DCT circuit 14 in a quantization step fed from a quantization index decision circuit 25. The quantization index decision circuit 25 decides a quantization index based on a 1st variable corresponding to a generated code amount as a data storage amount in a buffer 17 and a 2nd variable corresponding to a macro block activity outputted from an activity detection circuit 24 and a fixed value is selected for the 1st variable when one frame is coded.