Device for electrical variable magnification of document image

摘要

A system for altering the size of an image by a desired magnification after optical scanning thereof provides a plurality of output scan values differing in number from the number of sampled scan signals produced during the optical scanning. The output scan values are representative of the density of the image at pixel locations spaced across the image in dependence upon a selected magnification value. The system includes scanning means for providing the sample scan signals and converter means for converting the sampled scan signals to a corresponding sequence of digital scan values. A control circuit is responsive to a selected magnification value for providing a plurality of interpolation control values in synchronism with the sequence of digital scan values. The interpolation control values indicate the spatial relationship of output scan values with respect to pairs of successive digital scan values. An interpolation circuit is responsive to the sequence of digital scan values and to the interpolation control values and interpolates between pairs of the digital scan values to provide the output scan values.