Abstract: Methods and apparatus for image convolution using a one dimensional convolution operator to perform two successive convolutions, one in one dimension and one in a second dimension. A one dimensional convolution operator is provided with convolution coefficients and image data from a data matrix, and may also be provided with offset information, and stores the result of convolution in a first dimension in a buffer. Then for convolution in the second dimension, the results of the first convolution stored in the buffer are coupled back to the convolution operator for convolution in the second dimension. In a preferred embodiment, the result of the convolution in the second dimension for each of three color components is directed to an output buffer that selectively will provide as the output, the pixel data after the two dimensional convolution or the original pixel data. Alternate forms of convolution coefficients are disclosed.

Abstract: Methods and apparatus for smoothing an image representation for printing and display purposes. The invention recognizes that for smoothing purposes, there are only a limited number of patterns that require such smoothing, normally not exceeding a few hundred. It is therefore practical to compare an input image to a plurality of pre-determined patterns. If a match is found, then the input image is replaced by a corresponding pattern that was empirically found to be more suitable for the purposes of printing or display. Alternate embodiments of both the methods and the apparatus are disclosed.