Image encoding apparatus

A coding apparatus, comprising:

• a) block forming means for dividing sample values of an input signal into blocks;
• b) conversion means for orthogonally converting the blocks formed said block forming means, block by block;
• c) extraction means for extracting a D.C. component of the converted data output from said conversion means;
• d) a plurality of code amount estimation means for estimating code amount of coding of at least an A.C. component of the converted data output from said conversion means, by different quantization steps, said plurality of code amount estimation means each estimating the code amount by a predetermined number of blocks;
• e) control means for, in response to an output of one of said plurality of code amount estimation means, controlling the quantization step of another of said plurality of code amount estimation means or the quantization step used for coding of the A.C. component of the converted data;
• f) coding means for coding the A.C. component of the converted data by using the quantization step controlled by said control means;
• and
• g) output means for multiplexing the converted data coded by said coding means and the converted data extracted by said extraction means and outputting the multiplexed data.