Abstract: A continuous-tone image data is converted to a bi-level image data by halftoning conversion, then the bi-level image data i.e. binary image data is compressed by compressing means including predictive coding and image data compressing. These operations are done in a image coding apparatus. In this apparatus, when the continuous-tone image is converted into bi-level image data in halftoning so that predictions of predictive coding become strong. As a result, halftoning conversion is performed within a scope of binary image-coding-rules. This permits to produce a binary data easy to compress. Compressing a binary data in a low distortion quality and at a high compression rate is achievable through a method of image coding, and by an image coding apparatus of the present invention. Also a recording medium including a program carrying out this method is obtainable.

Abstract: Control to read signals from a sensor unit having a plurality of pixels by pixel blocks of a predetermined size, and the read signals are applied an operation to acquire distinctive information by pixel blocks of the predetermined size. The calculated distinctive information is applied to signal processes, such as signal compression, performed by a block.