DIGITAL DATA TRANSMITTING APPARATUS

A digital data transmitting apparatus comprises: an original block forming circuit for extracting image data in horizontal direction and/or vertical direction at intervals of a predetermined number of samples and forming an original block consisting of (n.times.n) pixel data; a differential block forming circuit for forming a differential block consisting of (m.times.m) pixel data with differential data between adjacent pixel data in horizontal and/or vertical direction and the pixel data concerned; a coding circuit for transform coding the original block and the differential block, respectively; a flag generation circuit for transmitting meaningful data of coefficient data generated by transform coding the differential block and generating a flag representing omission of the transmission of coefficient data where there is no meaningful data; and a transmission circuit for transmitting the flag and the pixel data of each of the block.