In a method and system and machine-readable medium, colors in an image (200) are unmixed (202) using a matrix X=AS, where A is a ns. ×nd matrix of spectral definitions, where ns is the number of spectral components and nd is the number of dyes into which the image is decomposed, and where S is a nd×l matrix of amounts of each dye at every pixel, where l is the number of pixels; the matrix X is constrained for solution by an unsupervised matrix decomposition method having constraints consistent with properties of an additive color model; and nd is determined. A texture is determined to identify areas of interest. Further processing may automatically measure cell dye concentration in the determined regions of interest.