Author Topic: ASinH stretch?  (Read 1419 times)

Offline akulapanam

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ASinH stretch?
« on: 2017 January 19 13:01:24 »
I came across a thread on another forum showing the power that ASinH stretching has to preserve star color and I was curious how to write a pixel math expression to mimic the that type of stretch.

Offline aworonow

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Re: ASinH stretch?
« Reply #1 on: 2017 January 19 13:38:04 »

Offline akulapanam

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Re: ASinH stretch?
« Reply #2 on: 2017 January 19 20:54:18 »
Thanks,  It maybe a "simplistic solution" and I haven't tried it so it may not even work really well.  On the other hand I find it hard to generate the really deep star colors that StarTools and it seems like maybe Iris (haven't used it) can generate.  I even have taken to masking the stars and saturating them separately with the curves tool, using repair HSV separation, and masked stretch.  Yet I throw it in a different program and I get deeper colors with the same data.

Offline akulapanam

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Re: ASinH stretch?
« Reply #3 on: 2017 January 19 21:19:06 »
I suppose part of this might not be the stretch but rather the LRGB combination method.  Perhaps a different method of combining Luminance with RGB vs. the LRGB process or replacing L in the LAB color space might help.

Offline sharkmelley

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Re: ASinH stretch?
« Reply #4 on: 2017 March 11 02:43:25 »
Quote from: akulapanam
I came across a thread on another forum showing the power that ASinH stretching has to preserve star color and I was curious how to write a pixel math expression to mimic the that type of stretch.

Try here:
http://www.cloudynights.com/topic/569440-pixinsight-arcsinh-stretch/
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http://www.markshelley.co.uk/Astronomy/