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Problem with transparent png

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Darren Cook

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Problem with transparent png

PostWed Jan 24, 2018 12:01 pm

Has anyone had problems importing PNGs into Fusion 9, that were exported from GIMP?
I had the original PNG import fine. Then I loaded it into GIMP, chose colour-to-alpha (#000000), and saved it as a PNG. Bringing that one into Fusion 9 the colours are an awful mess. (But that same PNG displays fine everywhere else - it is just Fusion that cannot display it properly.)

Strangely the alpha layer is correct; it is the green and blue layers that seem to have gone wrong (which in itself is curious, as it is a mostly red/orange image). I was even able to use the alpha layer from my GIMP-exported image as a mask on the original PNG to get the desired effect?!

Anyway, I instead exported from GIMP as a tiff file, and that imports into Fusion 9 with no problems. So that is the workaround if anyone else hits the same bug.
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Sander de Regt

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Re: Problem with transparent png

PostWed Jan 24, 2018 12:14 pm

Have you tried toggling the post/premultiplied options in the loader of the PNG? Usually this is part of the problem *and* solution with PNGs.
Sander de Regt

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The Netherlands
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Darren Cook

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Re: Problem with transparent png

PostWed Jan 24, 2018 2:14 pm

Brilliant, thanks!
When I check the "Post-Multiply by Alpha" checkbox in the "Import" tab of the loader, it loads as I originally expected it to, and behaves exactly like the TIFF file without that checkbox.

Even more curiously, if I check it on the TIFF file I get a different look (the more transparent areas look to have become even more transparent) - which is almost exactly what I just about to spend 15 minutes in gimp trying to get. (I also cannot find an apply mode in the merge node that gives that effect - "difference", when over a black background is closest, but not identical.)
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Chad Capeland

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Re: Problem with transparent png

PostWed Jan 24, 2018 5:01 pm

PNGs are defined as being straight color. TIFFs are defined as being premultiplied. Whoever decided on these standards knew they had to pick one, and so they did. Personally, I think straight color makes the most sense, especially for 8 bit images, but there's nothing any of us can do about it now, the standards are what they are.
Chad Capeland
Indicated, LLC
www.floweffects.com

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