Map sizes, grid size and map scaling

I have trouble with adding maps as the background. My original maps are large, 12600x9800 pixels or sometimes even larger. When I add them, Roll20 starts acting in a weird way so that mouse pointer is offseted by a number of pixels. Then I scaled them by 33% to get them to a manageable size and to get them mostly aligned with the grid on Roll20. This helped.

Now the only thing that is left is the size of the page. Is there a setting that would enable page size to follow the map size? Once you upload the map it would resize the page so that the page would fit the map and there's no need to tweak the page size later.

PS: Is it possible to zoom map with the mouse wheel?

Let's address map image issues first. That's a very large map. The grid is 70px per inch, but even if we doubled that to 140, that's still a 90x60 map. Not terrible, but still can affect performance. The Best Image Practices Page suggest that any image used for a map should be under 1 MB in size for best performance. I would suggest taking your map into an image editor, down sampling it to 70px per square and saving it as a jpeg with enough compression to get it closer to 1 MB. (Don't use png for maps if it can be avoided, you don't likely need transparency.)

It sounds like you have a handle on downsampling, most of that was for anyone reading along and to let you know about the Best Practices page if you were not aware.

Unfortunately, there is no page setting that automatically follows the map size. Many maps are pieced together from tiles, so any solution in that area would be of limited scope.

Finally, hold down alt/option while scrolling with the mouse wheel in order to zoom. Make sure you don't have a token selected, as that is also the combination used to rotate a token.

Yes, I downsized the maps and they are now in the range of ~500kB so that should work. Yes, I understand about the tiles, that's a valid point. :) I'll just prepare the pages and maps before we play.

I read about a script which can resize an image to the pagesize, but don't remember it's name or where I found it. You might wanna have a look in the Api-Forum.

Edit: https://app.roll20.net/forum/post/6285519/slug%7D