Count every one on a scanned drawing

A scanned sheet is only a picture: there are no lines to read. The program can still look for another copy of a symbol by comparing pictures. That’s a weaker kind of evidence than matching a drawing's own lines, so the program shows you every match as a small picture before it counts anything.

1. Press G and move over the scanned sheet. It says This sheet is a scan.
2. Drag a box round one example. Keep it tight: only that symbol, with a little white around it.
3. A window opens and looks. It shows every match as a picture, weakest first, each ticked.
4. Untick any that aren’t the same thing. The How closely it must match setting changes which are shown: Strict only the very closest, Rough includes some wrong ones.
5. Choose Create counts.

Each match shows a score such as “87% match”. That’s how closely the picture agrees with yours. It is not a probability that it’s right.

What it can and can’t find

• It finds copies at the same size, turned by quarter turns if you leave Count it turned round too ticked.
• It doesn’t find a copy drawn at another scale, or tilted at an odd angle.
• A plain shape can look like part of something else, which is why you look at each one.