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Processing colour in unbalanced exposures
Posted: Sat Dec 26, 2015 4:31 pm
by Lawrence
I'm puzzled about a quotation in the colour processing module:
"StarTools enables you to keep M42's colour constant throughout, even in its bright core. No fiddling with different exposure times, masked stretching or saturation curves needed. "
In M42 the trapezium stars are bleachd out in any normal exposure length so to maintain them as 'real' one has to take a separate exposure. The above suggestion implies that one exposure fits all. I am still a beginner with ST so I would appreciate a further explanation if possible?
TIA
Lawrence Harris
Re: Processing colour in unbalanced exposures
Posted: Mon Dec 28, 2015 10:35 am
by admin
Hi Lawrence,
StarTools will attempt to recover color in pixels that have not been overexposed in any of the channels. The "bleaching out" so often seen is an artefact of processing techniques; it is not inherent to the data. Stretching the data as a whole will cause colors to be stretched/compressed as well. This causes desaturation in the highlights and distortions elsewhere. By separating luminance and color and only stretching luminance, this distortion of coloring can be avoided.
Making a high dynamic range composite is never done to recover coloring, rather it is done to recover detail. Depending on how deep you'd like to go, a single exposure of M42 may indeed be enough.
I hope this makes sense,
Re: Processing colour in unbalanced exposures
Posted: Mon Jan 11, 2016 6:08 pm
by Lawrence
admin wrote:Hi Lawrence,
StarTools will attempt to recover color in pixels that have not been overexposed in any of the channels. The "bleaching out" so often seen is an artefact of processing techniques; it is not inherent to the data. Stretching the data as a whole will cause colors to be stretched/compressed as well. This causes desaturation in the highlights and distortions elsewhere. By separating luminance and color and only stretching luminance, this distortion of coloring can be avoided.
Making a high dynamic range composite is never done to recover coloring, rather it is done to recover detail. Depending on how deep you'd like to go, a single exposure of M42 may indeed be enough.
I hope this makes sense,
Yes, it does. Thanks. I'll look back at my data.
Lawrence