PHP GD resizing transparent image giving black border

Question

I am trying to downsize some transparents images in PHP with GD, and whenever I do, there is a weird black-ish border that is added around it.

Before

Answer 1

I think the problem here is your source image.

What you have is not a true-color PNG with alpha channel, but an indexed-color PNG with a transparent color. This is apparent if you open the image in Photoshop:

This image was created with anti-aliasing already (which gives the yellow text that white-ish border seen here), but when you re-size it, the sub-pixel calculations may go outside of their borders a bit.

I suspect if you fix the image, making it full RGB with an alpha channel, you won't have this problem.