_IMG files with memsize 0x06C0 are 40x40px icons.
Example:
Gardening tools icon 0x807887CD9C94AB88
It is not a simple matter to export these icons as transparent PNGs. Using version 0.2b of s4pe, I exported the image as a DDS file, opened it in Photoshop, selected the alpha channel, inverted selection, deleted the black area around the icon, then saved as PNG.