Add support to reproduce the dynamic range bug in PSNR
Add support to reproduce the dynamic range bug in PSNR

I think some academic paper has this bug.

nagadomi/waifu2x,vitaliylag/waifu2x,higankanshi/waifu2x,nagadomi/waifu2x,zyhkz/waifu2x,zyhkz/waifu2x,Spitfire1900/upscaler,higankanshi/waifu2x,zyhkz/waifu2x,nagadomi/waifu2x,nagadomi/waifu2x,zyhkz/waifu2x,Spitfire1900/upscaler,vitaliylag/waifu2x,vitaliylag/waifu2x,higankanshi/waifu2x,nagadomi/waifu2x