ABSTRACT
Non-linear stretching involves some form of tonal distortion. In PixInsight, stretching is achieved most conveniently with the Histogram Transformation tool. Digital Development Process is an interesting dilemma. It is a combination of a sharpening and stretch tool originally designed to mimic the appearance and sensitivity of photographic film. The example image suffers from excessive bias pattern noise, most noticeable in areas of faint nebulosity, even after calibration. In PixInsight, the adaptive contrast-driven noise reduction tool is an effective tool for reducing noise in non-linear images, as is the Multi scale Linear Transform tool (MLT), both of which can work at a defined structure size. Noise reduction and sharpening go hand in hand, and in PixInsight, they are increasingly applied in combination within the same tool. The MLT tool can not only be used for progressive noise reduction at different scales, but also to boost local contrast at a scale level, giving the impression of image sharpening.
