Fixed point image vs floating point inage comparison

[u/AlbbO_The_Great]

Hello, I'm doing a project on an FPGA for image processing. I'm at the stage where I've finished the verilog and already have the hex files generated, what I want to do is to compare that to my matlab floating point reference. Since, both are images, what metrics are best used for their comparison? I vaguely remember from a course where we determined the floating point vs fixed point error using LSBs, so like there would be an error of +/- 2 LSBs for example, but that was on 1D data. I dont know if thats still the case here for images.

[u/Adrienne-Fadel]

PSNR is what you want. It's basically MSE in dB and works on 2D too. SSIM if you care about perceived quality but for fixed vs float PSNR is enough.