mean gray value

Posted by entynemy on Mar 31, 2014; 10:06pm
URL: http://imagej.273.s1.nabble.com/mean-gray-value-tp5007158.html

I want to quantify the different amounts of the shaded areas between filter papers like in this hyperlink (  http://openi.nlm.nih.gov/imgs/512/392/3011902/3011902_f02_01.png  ). If I put the pic in gray scale and then measure for mean gray value I get a number like 211.007. Is this the value of shaded pixles added up?