Roll20 image resolution not quite as good as original image

I'm DMing Dungeon of the Mad Mage and am using some beautiful maps posted by deleeta87 on reddit.  The issue I'm noticing is that the map as viewed in Roll20 is not quite as good of a resolution as the original image viewed outside of Roll20.  See the side by side comparison below: Certainly, the image on the left (Roll20) is acceptable, but it not as crisp as the image on the right.  Given there's like 23 levels in DotMM, this will be recurring issue that will always bug me unless I fix it. The original is 7056 x 5124 resolution.  Given that Roll20 displays at 70 dot per square, the map in Roll20 is basically 100 x 72 squares.  The zoom in Roll20 is at 100%.  I'm using an imac with a retina display and using Chrome.  Any idea why there's a difference?  Is there anything I can do in Roll20 to get full resolution of the native image? 

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.

Thanks for your reply, Gold!  I can certainly make do with the resolution Roll20 gives me.  The players will never know that it's a little mushy.  So when I view the map object with Z or shift Z, it does indeed display the full resolution image.  Unfortunately, I won't be doing that for the players because then they see it all.