@JonB, thanks. Intuitively this seems like it should be faster and more efficient than going via the PNG conversion.
But when I went to test the performance I ran into a couple of issues with the asset approach:
Resulting image size is dependent on the size of the original ui.Image created.
Both the original and ”asset-applied” images are retained in the ui.Image somehow, and for example ButtonItems do not really handle that well.
See below couple of example images. First one uses a too-large initializing picture (Lenna), the second too small one (triangle arrow icon), which you can see presented in the title area.