Disclosed is a method of processing data from an image scanner for reducing image artefacts. The image scanner comprises a first image sensor arranged to: record a first set of lines, the first set of lines comprising a plurality of pixels representing recorded intensities of a first colour, record a second set of lines, the second set of lines comprising a plurality of pixels representing recorded intensities of a second colour; and record a third set of lines, the third set of lines comprising a plurality of pixels representing recorded intensities of a third colour. The method comprises the steps of: processing at least two of the first, the second or the third set of lines to create a first combined set of lines and filtering said first combined set of lines to filter out image artefacts creating a first filtered combined set of lines.