1. A method performed in an image processor for processing data defining an image scanned in the presence of mechanical vibration to produce a restored output image, the steps comprising: storing image irradiance data in a first memory, where each item of irradiance data stored therein represents a sample of an area of an original document; storing, in a second memory, velocity data associated with the image irradiance data, wherein the velocity data reflects a relative instantaneous velocity of a scanning element traveling at a nonuniform velocity measured with respect to the original document; modeling, using the image irradiance data and velocity data, an approximation function to represent image irradiance at any point in time; identifying control points as a function of a nominal scanning velocity and a fixed sampling time period; and resampling the approximation function, using the control points, to determine a restored irradiance level for each area of the original document.