Micrographs with Quantifoil grids have round holes surrounded by the grid background. There may be particles in the background area, but only particles inside the hole should be selected.

These batch files apply a circular mask to these images to eliminate the surrounding background:
cmask.bat
cmfull.bat

Micrograph	after cmask.bat

Source: quantifoil.html     Created: 5/31/01     Bill Baxter