I wanted to contribute a little info about custom icons. I’ve made over a thousand of them and in the process tried every image format out there as well as sizes ranging from 48X48 to 4096X4096. In addition, I’ve tried different bit-depths, color profiles, dpi resolutions, and output profiles. It was an exhaustive process because using the wrong baseline could mean eating up tons of iPad space when I didn’t have to. Where did I end up?
The overall best performance and visual quality comes from a simple 400X400, 72dpi, 8-bit PNG file. B&W average 25KB, color 225KB. You don’t need to go higher than that, even for very large buttons. MGP renders these PNGs really well across the board. 256X256 works reasonably well in most cases, but resizing gets a bit wonky with different layouts and edges will look fuzzy in some cases.
Also, if you want higher utility out of your icons, make them a single color and use opacity levels in your art to create depth. Knock out white or “dead” areas. When you do this, the icon will adapt to custom tinting in any usage, which is crucial for visual uniformity in your grids.
Hope this helps!
M.