GIMP Version: 2.8.10
Operating System: Windows
GIMP Experience: Beginner Level

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So it works for the most part, until i save it out as a .png. it will MOSTLY be transparent but when i im[port it into something like scribus, you can see a square around the image. drives me crazy. its not completely noticeable, but its there. haha..

please help me out. thanks. this is for a professional flyer.

EDIT
The color that gimp picked to make transparent was white. hex = ffffff

i found a work around for now but i would like to get it fixed. If after the color to alpha, i do a alpha to selection, copy it and paste it onto a new transparent layer, it works fine, but for some reason the transparent layer after i do color to alpha LOOKS transparent in gimp but it is not fully transparent in other programs

When I do that I end up with a semi transparent layer, so to fix that, I make a transparent layer under that layer and paint inside the image with white, then I merge down.
You can go alpha to selection so you don't get white outside the selection.

So why is it semi transparent for us when we do that? Is it a bug?

thanks

Color to alpha works. If you get something left around the image, it's because the original color wasn't the one you thought (did you use the color picker?) or wasn't completely uniform. If the original image is a JPEG, even at high quality, there are faint JPEG artifacts near sharp edges which aren't completely white so C2A won't make these completely transparent.

It always useful to check the results against a dark or light background.

In many cases C2A is only important on the edge pixels so:

1) make a fuzzy select on the background
2) grow the selection by 2 pixels so that it includes the edges
3) apply C2A
4) shrink the selection by 4 pixels (ie leave a margin of 2px around the subject)
5) [delete] for a clean backrground.

I am checking transparency on images everyday to moderate them for the site I admin for. I made this little script to make things easier for me. Maybe you can get some use out of it.
It will create a layer group of 5 layers with the following colors and put them at the bottom of your image.

FFFFFF
000000
5C5C5C
00FF00
FF0000

If you don't see any stray pixels against these colors, you are probably pretty safe.
There are of course exacting ways to do this as well, but is usually more trouble than it's worth.

Lastly, another trick I use to remove stray pixels is to use the curves tool and set the channel to alpha. Moving the bottom node to the right will start to fade away anything that isn't full transparency. Inversely, moving the top node to the left will increase the opaqueness. Works pretty good to render hair when it is against a solid contrasting background after a color to alpha.

Thank you akovia,