Compressing a regular scan image using coding parameter from the prescan image

Abstract

An image data compressing method of the type in which a multi-valued image data signal read by an image input unit is compressed by an image data compressing circuit to be stored into a memory. In the image data compressing method, the image input unit performs a prescan, thereby to obtain prescan image data containing pixels smaller in number than those contained in image data of an original image Next, a definition of the original image is estimated on the basis of the prescan image data, thereby to obtain coding parameters for the image data compressing circuit. Then, the image input unit performs a regular scan, thereby to obtain regular scan image data containing all of pixels of the original image data. Finally, the regular scan image data is compressed using the coding parameters previously obtained.

Dependencies are inferred from the claim text.