Patent ID: 7570821

Claim:
An image coding apparatus comprising: (A) plural scan units which correspond to each of plural scan sequences different from one another, and each having (a) a scan means scanning an original image to be encoded according to a prescribed scan sequence, and (b) a piecewidth linear approximation (hereinafter referred to as “PLA”) means dividing a one-dimensional (hereinafter referred to as “1D”) original image generated by scanning said original image with said scan means into plural intervals so that one of an accumulated square error and a dispersion of pixel values in each interval is a prescribed threshold value or less to generate 1D approximation image data obtained by approximation of pixel values by an average value of pixel values in the interval; and (B) optimal scan selecting means comparing the numbers of intervals obtained by division by said PLA means for each said scan unit to thereby select said 1D approximation image data having a minimum number of intervals.