PNG transparency viewing in some programs / websites

Question

I have made a PNG file, PNG-24 with transparency using Photoshop CS5, which if i upload straight to stack overflow looks like this:

When this is uploaded to some websites, such as Facebook or Soundcloud (as cover art for a song) it renders fine. However,when dragged into a twitter message it looks like this:

does anyone know why some programs render the image and somehow include layers of the original photoshop document that should have been removed?

this also happens in some programs, names an mp3 id3 tag editor (Mp3tag v2.50) when trying to use the png as cover art.

is there a better way to make a PNG which has all this additional information removed?

thanks a lot

Answer 1

The difference you are seeing is in how the different software processes the transparency information in the image stream.

When you set the transparency, you did not delete the underlying image.

If you want to get rid of the rest of image, you need to edit it differently. First clear all the pixels you have set transparent (e.g., set them to white). Then make that area clear. That way, if the display software does not process transparency, it will display white rather than the part of the image you did not want to see.