Where there is a perceptual hue difference between adjoining pixels – a perceptual difference is one where the colour name is different – or a brighness difference greater than the one specified, the output places a pixel and, by option, continues this horizontally at a colour that is the average of those affected before another change takes place.

By this mechanism it might be possible at a later stage in my software developments to identify by software what are the significant blocks or shapes of colour in an image.