I think you are confused about the purpose of an ATF. An ATF is a holder for multiple kinds of GPU graphics formats. The point of the ATF is to store things that are already compressed so that you save VRAM and you have a shorter GPU upload time when you use them in a mobile app. By default if you use a PNG file, the uncompressed file is uploaded to the GPU which uses a lot of memory. It is also a large asset for your app. But if you simply use PNG files, you are already "generating" the equivalent of what's inside an ATF file, because ATF files can contain uncompressed versions as well. If the ATF file is not compressed by TexturePacker (PVR) or png2atf (ETC1/2) there is no real benefit in terms of size, memory footprint, or upload time. That is why it takes so long and so much memory to use PNG files...an uncompressed ATF will use exactly as much memory, because an ATF is just a holder for a raw image format of one kind or another. If you actually wanted to compress PNG files using PVR-3 and lossy compression for example, like what TexturePacker does, on the mobile device, you would be waiting for hours. Actually sometimes it takes 5 minutes on a macbook to compress a 4096x file. ATF is good for pre-generating what will go on the GPU, otherwise just use a PNG. You cannot convert PNG>PVR or PNG>ETC at runtime through any known AS3 code and there would be no point to do so unless you wanted compression, and the whole point of compression is so you don't have to load the large PNG or upload it to the GPU in the first place. So basic answer is no, and there would never be a reason to.