Color retention

Non-linearly stretching an image's RGB components causes its hue and saturation to be similarly stretched and squashed. This is often observable as "washing out" of coloring in the highlights.

Traditionally, image processing software for astrohptography has struggled with this, resorting to kludges like "special" stretching functions (e.g. ArcSinH) or Color enhancement extensions to the DDP algorithm (Okano, 1997) that only attempt to minimize the problem, while still introducing color shifts

While other software continues to struggle with color retention, StarTools Tracking feature allows the Color module to go back in time and completely reconstruct the RGB ratios as recorded, regardless of how the image was stretched.

This is one of the major reasons why running the Color module is preferably run as one of the last steps in your processing flow; it is able to completely negate the effect of any stretching - whether global or local - may have had on the hue and saturation of the image.

Because of this, the digital development color treatment extensions as proposed by Okana (1997) has not been incorporated in the Develop module. The two aspects - color and luminance - of your image are neatly separated thanks to StarTools' signal evolution Tracking engine.