A method for measuring residual protein in a cellular specimen including obtaining a low magnification image of a candidate object of interest, filtering the candidate object of interest pixels with a low pass filter, morphologically processing the candidate object of interest pixels to identify artifact pixels, identifying the candidate object of interest by eliminating artifact pixels, acquiring a higher magnification image of the subsample for the candidate object of interest, transforming pixels of the higher magnification image in a first color space to a second color space to differentiate higher magnification candidate object of interest pixels from background pixels, identifying an object of interest from the candidate object of interest pixels in the second color space, and determining the optical density of the protein in a cell contained in a subsample, wherein the optical density is indicative of the residual component of a cellular protein.