An orthogonal transform such as a DCT is carried out for image data D5 of
an image in blocks obtained by dividing a frame image, the image data D5
being represented by spatial coordinates (Step S102), and a plurality of
orthogonal transform coefficients D6 as image data represented by spatial
frequencies are generated. Then, the orthogonal transform coefficients D6
undergo arithmetic coding, and thus coded data D7 is generated (S103).
Subsequently, in the arithmetic coding of the orthogonal transform
coefficients, data characteristics of the orthogonal transform
coefficients to be coded, which depend on the spatial frequencies, are
considered, and a probability table is switched for a predetermined
orthogonal transform coefficient, and thus the arithmetic coding is
carried out. Thus, the image coding method, image decoding method, image
coding apparatus, image decoding apparatus, program, computer data
signal, and image transmission system, which are capable of enhancing
efficiency of data compression in coded data by reflecting
characteristics of image data to be coded on coding conditions, are
realized.