Alpha (transparency) procedure not working about gimp-plugin-bimp HOT 5 CLOSED

Actually it works for me, in particular on images that don't have a "native" alpha layer. Maybe you are saving them back to JPEG (or equivalent non-alpha) format?

This is a JPEG input image, obviously without transparency:
http://i39.tinypic.com/2ia7h1f.jpg

I put it on my batch process and select the plug-in-colortoalpha with #FFF as color to remove. ALSO, I add a Change format step in order to save it on PNG.
http://i42.tinypic.com/jhd3lw.jpg

The result is the following:
http://i43.tinypic.com/1493xon.jpg

And this is what happens if I don't include the Change format step, the image is saved back to JPEG and loses the alpha channel:
http://i44.tinypic.com/2wf3389.jpg

(sorry for the images size, I noticed just now)

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Please reopen - this actually only works if you add 'gimp-convert-rgb' before the color to alpha.

This is happening on Windows7, Gimp 2.8.6.

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This is not actually true, or better, in the example I wrote before I didn't add a 'gimp-convert-rgb' step and it worked.
Your problem could be realed to the type of images you are using as input. In order to work with transparency, the input format must be RGB.
You probably see a strange behaviour because you are passing on BIMP a grayscale or indexed image, and it naturally needs to be converted before by GIMP. I don't see it as a real "issue"...

Anyway, could you send me one of the images that produce this problem?

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You can see that on these: https://github.com/subtlepatterns/SubtlePatterns

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Yes, I see. Those images (I've tried with only few of them, btw) are in "grayscale" format. That means that they haven't any alpha channel and the 'plug-in-colortoalpha' doesn't support them as input. They must be converted in RGB before and this is the case in which you have to use 'gimp-convert-rgb'.
Its not a bug, it's GIMP itself ;)

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