I am a big fan of NG Gallery and so far have used it with minimal, make that negligible, problems. However, a group of my students developed a WordPress site where they are presenting portfolio images in PNG format with transparent background. The images display with no problem at all. However, the transparency is being rendered as black background on the thumbnail images created by NG libraries.
I have noticed quite a few inquiries about this problem with no resolution. I am writing once more to ask for assistance from the developer who has given us a wonderful tool to use. The problem seems to be related to libraries rather than the core of NG Gallery, so I am not sure if the plugin author will be inclined to provide a fix. I hope that there will be a clear, once and for all, reply to give the users some direction and what to expect.
I am using a workaround of recreating the thumbnails off site and uploading over the NG generated thumbnails. It is a hack, but it works without giving the site an odd look.
Please, Alex, give us some information as to where you stand on this problem.