Processing device for changing magnification of image data

Abstract

A processing device for changing magnification of image data applicable to a digital copier, a facsimile transceiver and other image processing apparatuses changes a magnification electrically, i.e., produces magnification-changed image data by estimating data with a changed magnification from data which are read with a 1 magnification. Nearby ones of original image data are sampled at a predetermined pitch and in synchronism with a data clock DCLK on the basis of a magnification R, which is specified on a 1% basis, so that magnification-changed image data Oij are computed and outputted in synchronism with the data clock. This realizes real-time processing, i.e., produces magnification-changed image data timed to the reading of an original image. Computations for MTF compensation are performed in matching relation to magnifications Rx and Ry, which respectively are specified in the main scanning and subscanning directions, so as to suppress deterioration of an image due to the change of magnification. Moreover, the computation of magnification-charged image data and that of MTF compensation in the main scanning direction are executed in a pair, and so are done the computation of magnification-changed image data and that of MTF (modulation transfer function) compensation in the subscanning direction. This ensures optimum MTF compensation in both of the main scanning and subscanning directions even if the magnifications Rx and Ry are different from each other, allowing a minimum of degradation of image quality with regard to the whole image.