Image-processing raster and serial-format image data

Abstract

Serial-format image data inputted from a scanner is subjected to scaling processing based upon linear interpolation performed by a linear-interpolation processor. Since the scaling processing is applied to serial-format image data, a line buffer that stores one line of pixels necessitated by the method of linear interpolation need only have a capacity of one main scanning line in the serial format. One main scanning line in the serial format corresponds to the number of elements arrayed in the reading head of a scanner and is sufficiently small in comparison with one line of capacity in a raster format. Image data thus subjected to scaling processing is converted into the raster format by a vertical-horizontal conversion processor and the resulting data is stored in an image memory. Image data read out of the image memory also is subjected to scaling processing after being converted into the serial format. Furthermore, at the time of scaling processing, it is determined where a character has been superimposed upon the image data. If an area is occupied by a character, then scaling processing is performed by a simple iterative method. Otherwise, scaling processing is carried out by linear interpolation. This makes it possible to record sharp characters.