Types of machine-readable form
Black-and-white forms with raster borders
Field outlines on black-and-white forms with raster borders are sequences of small dots that despeckling removes, with dot size and spacing rules.
These forms have no background. All field borders (of character cells, checkmark fields, and other form elements) consist of raster lines, which are sequences of small black dots.
Raster dots are usually 0.39-0.5 pt, with a recommended size of 0.39 pt, and the distance between dots should be at least five times the dot size. Dot size and spacing are crucial, because ABBYY FlexiCapture removes these raster dots during despeckling rather than during scanning, treating them as garbage. For this reason, the dots must not be glued together on scanned images.