Hi,
I'd like to remind that PTE AV Studio 10.5 supports images in WEBP format. A great benefit of this format is a transparency (alpha channel) with a lossy compression, like a JPEG. It allows to save very compact files with transparency.
PNG with a transparenct is an old good solution. But it doesn't works well for a compression of photo realistic images with transparency. Usually file is very large, due to lossless compression.
WEBP offers possibility of lossy compression like a JPEG keeping transparency layer. These photo realistic images usually smaller than PNG in 3-10 times. A very good idea to use them in slide styles or EXE shows.
If your image editing app doesn't support export to a WEBP format, you can use a free online image editor/converter: photopea.com