If you have an enormous fonts collection, you can search for a font using a bitmap sample of one of its glyphs. Either feed Fontmatrix a ready bitmap file or use Grab mode to fetch an image from your display.

Click on the glyph in the raster sample preview so Fontmatrix can compute its bounding box. If the box is wrong, enable Tweak rect and drag the corners. Type the character that the sample shows and press Search.