Method and apparatus for filtering images having insufficient tonal precision

摘要

An array of n-bit words representing an image is filtered to produce a corresponding array of higher precision m-bit words representing the image. During the filtering, upper and lower bounds for the m-bit words are identified, and values for the m-bit words are selected between the upper and lower bounds. There is at least some spatial smoothness between the selected values. For example, the values may be selected at sample points of a curve or surface between the upper and lower bounds.