It's some sort of tool or something...
Ok, so it's basically a thing that tallies up how many pixels of different colours there are in an image. I had the idea while working on the trans rememberance image and thought it could be useful to see how much of the image was each colour (of blue, pink & white). In the end I never actually needed it but I still made this and idk, I think it's neat. Maybe you'll find a use for it but I just enjoy seeing what colours are in different images.
The rounding basically groups similar colours together (it rounds each channel down to a multiple of 2, 4, 8, etc. so if set to, say, 8, anything in between, say, #40b8f0 (64, 184, 240) and #47bff7 (71, 191, 247) would be grouped). Useful for images with many distinc colours, as most do. I highly recommend using higher rounding for such images as if it's counting up hundreds of thousands of different colour ranges it can be quite slow.
The gradient shown beside each colour range is roughly in the middle of the range.