Standard deviation of a template's visible brightness on the 0 through 255 scale, so roughly 0 through 128 in practice. Under about 5 the template is nearly one flat colour, correlates with any area of that colour, and cannot be located reliably; a distinctive template usually measures 20 or more.
Standard deviation of a template's visible brightness on the
0through255scale, so roughly0through128in practice. Under about5the template is nearly one flat colour, correlates with any area of that colour, and cannot be located reliably; a distinctive template usually measures20or more.