faeriebasil If I remember correctly, when you use png:
First copied into RAM. (First Copy-Permanent in RAM)
Than turns into Texture in RAM. (Second Copy-Permanent in RAM)
Than uploads into GPU RAM (Third Copy)
PNG makes two copies in RAM with AIR, I don't know why, maybe there is ways to improve that.
When you use ATF:
0 RAM usage after GPU upload
GPU RAM used as usual
So when you use ATF, RAM usage decreases. Maybe there can be one copy in RAM in ATF usage, I don't have time to check right now, but I remember as 0 copies.
Even with one copy in RAM usage is still %50 down. And that is big if you have many PNGs. Each png can fill 32 MB in RAM at 2048*2048 resolution.
GPU RAM usage also goes down because ATF is hardware compressed. Usage much smaller than PNG usage.