The use of color coding accentuates amplitude variations in the "gray scale" of B-scan ultrasonography. Color coding by means of selected "sliced" amplitudes uses red for high amplitude echoes, green for moderate amplitude echoes, and blue for low amplitude echoes in order to accentuate spatial relationships of echoes within tumors, foreign bodies within hemorrhage or tissue, and membrane or retina within vitreous hemorrhage. Color coding systems allow for easier detection of variations in echo amplitudes and the display of these echoes over a larger portion of their dynamic range, features that are essential for ultrasonic diagnosis of tissue abnormalities.
Coleman DJ, Katz L. Color Coding of B-Scan Ultrasonograms. Arch Ophthalmol. 1974;91(6):429-431. doi:10.1001/archopht.1974.03900060443001