Thread: star colours
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Old 10-11-2014, 11:32 PM
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Shiraz (Ray)
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Location: ardrossan south australia
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It's a good question Alistair.

as I see it, stars are white for two reasons:
1. if they are saturated, the cores will have equal values of R,G and B (65k), so they will be white.
2. when you stretch data to bring out dim stuff, you must also compress the bright end of the data, so that the star cores all end up with similar values - eg a star may have started out with R,G,B of 20k, 30k, 40k, but after stretching you might have 62k, 63k, 64k (ie you compress the channel ratios and the result is again almost white).

I assume that images with deep coloured stars have been modified to overcome the above by taking some star data with short subs to get around saturation and/or by applying different stretching to the stars to keep a better representation of the original RGB ratios (or selectively saturating them post-stretching)

Last edited by Shiraz; 11-11-2014 at 12:46 AM.
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