I used Andy Pope's add-in to save my custom button icons as .bmp files.

To use them in my add-in, instead of trying to load them from the .bmp files
directly, I used insert/image to put each .bmp on a worksheet in my add-in.
I then use code to paste them to my new toolbar.

The problem is that I seem to have quality problems in (at least) two
places; when I insert a .bmp and enlarge it for analysis, the picture is
similar to the original, but blurry (I'd expect it to just show a large
16x16 block of colors). Then when I paste it to the toolbar- then copy that
image back into Andy Pope's editor, the end result shows that the image had
further degraded.

I'd like a clean (and transparent) .bmp on my final toolbar, but many google
searches have turned up nothing.

Is there a preferred approach to ensure that the button image quality
remains stable/clean all the way through to the final toolbar?

Thanks!
Keith