Processing images of media items before validation

Automatic media item validation is typically problematic in the case of media items that are damaged or marked. The present invention relates to a method of processing images of media items before automatic validation which addresses this problem. Aberrant image elements are identified, for example, using a bandpass filter. The aberrant image elements are replaced by neutral decision making data. This data is neutral with respect to a decision making process being a specified automatic media item validation process. For example, for each aberrant image element an estimated distribution is accessed for that image position across all images in a training set of images of media items. A value is selected from the estimated distribution on the basis of a significance level which is related to a significance level used by the automatic media item validation process. In this way media items which have tears, holes, marks or soiling may be successfully processed by an automatic media item validator.