All icon and other PNG files are derived from a Photoshop file.  The Photoshop
file has multiple layers, which need to be enabled or disabled when producing
the various PNG files.  A full description of which layers need to be adjusted
is in Photshop Notes.xlsm, an Excel worksheet.

Smaller icons require manual editing for best appearance.

Windows .ico file should contain 16x16, 32x32, 48x48, and 256x256 images.  We
also include 24x24 for Windows XP compatibility.
A .ico file can be built at the website icoconvert.com.

MacOS .icns file should contain:

    Icon size (@1x) 	                Icon size (@2x)
    512px × 512px (512pt × 512pt @1x) 	1024px × 1024px (512pt × 512pt @2x)
    256px × 256px (256pt × 256pt @1x) 	512px × 512px (256pt × 256pt @2x)
    128px × 128px (128pt × 128pt @1x) 	256px × 256px (128pt × 128pt @2x)
    32px × 32px (32pt × 32pt @1x) 	    64px × 64px (32pt × 32pt @2x)
    16px × 16px (16pt × 16pt @1x) 	    32px × 32px (16pt × 16pt @2x)
	
The .icns file can be edited on Windows using the Greenfish Icon Editor.