Abstract: An image processing apparatus in a reproduction system includes an image input terminal having a device resolution of K pixels per unit length by L pixels per unit length (K x L). Each pixel is defined at a depth b representing one of b optical densities. The image input terminal emits an input image at the device resolution and depth (KxLxb). A memory is provided for receiving and storing as electrical signals the input image emitted from the image input terminal. A first processing means converts the resolution of the input image to a plurality of output images at a second resolution of M pixels per unit length by N pixels per unit length (M x N). Each pixel is defined at depth d representing one of d optical densities. The first processing means converts the input image to the plurality of output images by spatially offsetting a periodically repeating mapping defining the conversion between the input image and the output image.

Abstract: In a method for converting from a first bitmap image resolution to a second bitmap resolution, be it interpolation (an increase in resolution) or decimation (a decrease in resolution) a bitmap image defined at resolution and density I.times.J.times.a is prefiltered as a first step to ensure the preservation of original image structure and compensate for device dependence of the input image, which is necessary in order to maintain the quality and sharpness of the original image. The filter may be selected from a variety of filter choices and may also perform pixel interpolation or decimation depending on the input source. As a second step, unquantized scaling of a prefiltered image (K.times.L.times.b) is performed using an f.times.g pixel window to identify a set of neighboring input pixels surrounding a single output pixel. The window contributes input pixel density information to generate a scaled gray output pixel.

Abstract: A method for converting a set of input image pixels having a first resolution and being represented by a set of input image signals to a set of output image pixels having a second resolution and being represented by a set of output image signals. The method is adapted for use in an electroreprographic machine having a memory for storing images and an image output terminal for printing the images.

Abstract: A method for converting binary image data originally generated at a lower resolution into representative binary image data of a higher resolution, wherein the conversion ratio, or magnification factor, is an integer value. Also included are methods for smoothing the interpolated output image and thereby reducing objectionable visual characteristics observable in digitally encoded data using conventional magnification techniques.