I discovered about 150 dots is the minimum number of dots to make a specific recognizable person. You can make something that looks like a head, with fewer dots, but you won't be able to give much information about who it is.

Early life and education
Close was born in Monroe Washington. If you impose a limit to not do something you've done before it will push you to where you've never gone before. See also
List of Chuck Close subjects
The Portrait Now.

Charles Thomas "Chuck" Close (born July 5 1940) is an American painter and photographer who achieved fame as a photorealist through his massive-scale portraits. Though a catastrophic spinal artery collapse in 1988 left him severely paralyzed he has continued to paint and produce work that remains sought after by museums and collectors. Close currently lives and works in New York's West Village and in Bridgehampton New York.