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celstark / OpenNebulosity

Astrophotography capture and processing
BSD 3-Clause "New" or "Revised" License
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Guidance on Use of Arcsinh Stretch #5

Open jvickroy opened 8 months ago

jvickroy commented 8 months ago

Hello.

I do not know how to use the Arcsinh stretch tool in Nebulosity 4.4.4. Scale factors <1 and >1 both produce pixel histograms with peaks shifted far to the right so the resultant images are severely bleached.

I would appreciate guidance on how to proceed.

Thanks, /jim

celstark commented 8 months ago

All the tool does is, for each pixel, compute the arcsinh of that value – just a standard math function. For some images it may be a useful transformation while for others it may have bad effects.

From: jvickroy @.> Date: Monday, January 29, 2024 at 6:42 PM To: celstark/OpenNebulosity @.> Cc: Subscribed @.***> Subject: [celstark/OpenNebulosity] Guidance on Use of Arcsinh Stretch (Issue #5)

Hello.

I do not know how to use the Arcsinh stretch tool in Nebulosity 4.4.4. Scale factors <1 and >1 both produce pixel histograms with peaks shifted far to the right so the resultant images are severely bleached.

I would appreciate guidance on how to proceed.

Thanks, /jim

— Reply to this email directly, view it on GitHubhttps://urldefense.com/v3/__https:/github.com/celstark/OpenNebulosity/issues/5__;!!CzAuKJ42GuquVTTmVmPViYEvSg!ORyvYT1S5YQWrHEBw4j3bbbZHmLRlNjc0ix-iI_p3PfoYY-qxfvXCpaSENuo5IYYNw21dfZaMmIw9nVKo_HxgjI$, or unsubscribehttps://urldefense.com/v3/__https:/github.com/notifications/unsubscribe-auth/ACJBVHQ2GQPIXB3O4QUV3HLYRBMZBAVCNFSM6AAAAABCQPF3DGVHI2DSMVQWIX3LMV43ASLTON2WKOZSGEYDMOBTG43TENQ__;!!CzAuKJ42GuquVTTmVmPViYEvSg!ORyvYT1S5YQWrHEBw4j3bbbZHmLRlNjc0ix-iI_p3PfoYY-qxfvXCpaSENuo5IYYNw21dfZaMmIw9nVKEVtEYqI$. You are receiving this because you are subscribed to this thread.Message ID: @.***>

jvickroy commented 8 months ago

Thanks, Craig for taking the time to respond and thanks for Nebulosity. I will have to learn more about which types of images this stretch may be helpful. /jim

From: Craig Stark @.> Sent: Tuesday, January 30, 2024 10:09 AM To: celstark/OpenNebulosity @.> Cc: jvickroy @.>; Author @.> Subject: Re: [celstark/OpenNebulosity] Guidance on Use of Arcsinh Stretch (Issue #5)

All the tool does is, for each pixel, compute the arcsinh of that value – just a standard math function. For some images it may be a useful transformation while for others it may have bad effects.

From: jvickroy @.> Date: Monday, January 29, 2024 at 6:42 PM To: celstark/OpenNebulosity @.> Cc: Subscribed @.***> Subject: [celstark/OpenNebulosity] Guidance on Use of Arcsinh Stretch (Issue #5)

Hello.

I do not know how to use the Arcsinh stretch tool in Nebulosity 4.4.4. Scale factors <1 and >1 both produce pixel histograms with peaks shifted far to the right so the resultant images are severely bleached.

I would appreciate guidance on how to proceed.

Thanks, /jim

— Reply to this email directly, view it on GitHubhttps://urldefense.com/v3/__https:/github.com/celstark/OpenNebulosity/issues/5__;!!CzAuKJ42GuquVTTmVmPViYEvSg!ORyvYT1S5YQWrHEBw4j3bbbZHmLRlNjc0ix-iI_p3PfoYY-qxfvXCpaSENuo5IYYNw21dfZaMmIw9nVKo_HxgjI$, or unsubscribehttps://urldefense.com/v3/__https:/github.com/notifications/unsubscribe-auth/ACJBVHQ2GQPIXB3O4QUV3HLYRBMZBAVCNFSM6AAAAABCQPF3DGVHI2DSMVQWIX3LMV43ASLTON2WKOZSGEYDMOBTG43TENQ__;!!CzAuKJ42GuquVTTmVmPViYEvSg!ORyvYT1S5YQWrHEBw4j3bbbZHmLRlNjc0ix-iI_p3PfoYY-qxfvXCpaSENuo5IYYNw21dfZaMmIw9nVKEVtEYqI$. You are receiving this because you are subscribed to this thread.Message ID: @.***>

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