Sounds like you get the parameters at play, you've got the best there that can be done. It's just you have a sharp eye, and an incredible monitor (the retina quality display), you're noticing a slight difference that most people won't notice (especially if they don't have the benefit of a side-by-side original). You could go to 110% zoom in Roll20 and see if you like the appearance-of-sharpness better. You can press Shift-Z while the graphics object is selected to show it in the largest size that fits in your screen. If the graphic size is smaller than your screen resolution then you'll be seeing it in "original" quality in that method. Yes, as you've figured out here, the version of your image that's likely to be showing on your VTT canvas, even at 100% zoom, may be one of the converted/resampled images Roll20 stores and not necessarily the original.png version of it. When you upload a pic roll20 in background automatically makes thumb-size, med-size, and "max" size versions of it, while also holding on to "original" version. It may also create slices or sub-tiles in order to load only-the-part-of the image that's in the user's canvas viewport at the time. So yeah there's transcoded versions swapping around in the background, that's part of the magic of roll20 being able to run on the web browser and serve all these images in different views.