Mobile hdr image

Question about using hdr in mobile. Do I need to re scale the image? I’m just curious as the file size on an hdr I have is pretty large. I’m a bit worried that I’ll have issues cooking later. Does the engine optimize down the file size. It’s 300mb, and I have it working in mobile preview editor right now. I’m just a bit worried when I build I may add a lot of non necessary file size.