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Compositor is altering the colors and anti aliasing of images. I have outputed 2 image sequences in png highest quality. One opengl and one freestyle render with alpha transparency.

When combining those image sequences in Blender (simple image sequence node with alpha over) the compositor is altering the freestyle image on load. It is altering the line thickness and some white lines (on the blue crystal) are appearing thicker and jagged now. If using the same input in photoshop the white lines appear correct and are way thinner.

Any insight on this problem? I have the feeling it is something with transparency.

Blender composer output enter image description here

Photoshop output enter image description here

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    $\begingroup$ This reminds me of a problem I was having in the compositor. Check my previous question/ blender.stackexchange.com/questions/51154/… Also did you check if you saved/load your images as a 8bit or 16bit file format? $\endgroup$ – Delagone Nov 18 '16 at 8:30
  • $\begingroup$ Thanks. It was not the settings, it was the 16 bit file format which caused the trouble. Will post this as the answer. $\endgroup$ – Wasili Novratidis Nov 18 '16 at 8:54
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The worthless format known as PNG.

Render using half float 16 bit EXR.

The issue is crappy unassociated alpha that is enforced with that abysmal format known as PNG. You could also use the "Convert Premul" option to properly associate the alpha channel.

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    $\begingroup$ HAH, PNG again :) First Hjalti at the Blender Conference failing at running a GIF live, and now PNG giving Alpha hell to just about any artist out there. Skeletons from the past. Can't the world just agree on the concept of banning non-associated alpha? :) $\endgroup$ – aliasguru Nov 19 '16 at 6:41
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    $\begingroup$ @aliasguru PNG has a single role: Web delivery where you absolutely must have transparency. That said, it is such a deficient format as to be avoided like the plague when dealing with imaging development, and handled extremely carefully when going to the web. I am sure your experience with it could fill a tome. $\endgroup$ – troy_s Nov 19 '16 at 15:22
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As stated by Delagone. If compositing in this way make sure to render the freestyle images as 16 bit.

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