Author Topic: TIFF bit depth  (Read 192 times)

Offline dchamberlain

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TIFF bit depth
« on: 2019 October 18 09:42:15 »
Hello everyone,

When I process my images in PixInsight I usually save a TIFF copy in 16 bit after I save the XISF file. The reason is because I cannot find any other way to successfully bring the image into PS for additional tweaks. If I save it as 32 bit, PS brings it in with everything brighter than the original (brightness and saturation). Also, PS disables certain filters if the image is in 32 bit more. If I convert it to 16 bit inside PS, the image contrast is way off. The only way I can preserve what the original (XISF) image looks like in TIFF when I bring it into PS is to save it as 16 bit.

So here is my ask: is there a way to save the image in 32 bit that will work with PS?
If not, is there a way for PI to default TIFF saves to 16 bit? (It defaults to 32 bit IEEE 754 floating point) - I haven't found anything to change this in the Format Editor.

Thanks

Dale

Offline dave_galera

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Re: TIFF bit depth
« Reply #1 on: 2019 October 18 10:36:23 »
Download and install an OLD version of FitsLiberator that implements as a plugin to Photoshop then you can import FITS files.

I am assuming, of course, that the plugin version of FitsLiberator still works with current flavours of PS.
Dave

Offline dchamberlain

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Re: TIFF bit depth
« Reply #2 on: 2019 October 18 14:53:43 »
Download and install an OLD version of FitsLiberator that implements as a plugin to Photoshop then you can import FITS files.

I am assuming, of course, that the plugin version of FitsLiberator still works with current flavours of PS.

From their website it looks like PS plugins are no longer supported as they have made it a standalone application.  So this really won't be a solution for me.

Offline Geoff

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Re: TIFF bit depth
« Reply #3 on: 2019 October 19 00:10:22 »
You don’t really need PS. PixInsight is perfectly adequate for all astro processing. You just have to bite the bullet and ditch PS.
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Offline sharkmelley

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Re: TIFF bit depth
« Reply #4 on: 2019 October 19 03:44:46 »
Be aware that 32bit mode in Photoshop is a special linear mode.  It behaves very differently to 16bit and 8bit modes.  Photoshop assumes that 32bit data is linear and therefore applies a gamma transformation to the data which it does not apply for 16bit and 8bit data.  This is why opening a 32bit file in PS looks quite different to opening the equivalent 16bit file.  The issue is with Photoshop and not with PixInsight.

To get overcome this issue you need to perform some complicated operations with bespoke embedded ICC profiles and/or pre-transform your 32bit data.

Mark
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http://www.markshelley.co.uk/Astronomy/

Offline dave_galera

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Re: TIFF bit depth
« Reply #5 on: 2019 October 19 05:00:56 »
Download and install an OLD version of FitsLiberator that implements as a plugin to Photoshop then you can import FITS files.

I am assuming, of course, that the plugin version of FitsLiberator still works with current flavours of PS.

From their website it looks like PS plugins are no longer supported as they have made it a standalone application.  So this really won't be a solution for me.

Version 3 is standalone, you have to download version 2
https://www.spacetelescope.org/projects/fits_liberator/download_v23/
Dave