Following research reported by the authors to SPIE (2015) and SID (2017), this paper pursues further psychophysical research to the determination of 255 Just Noticeable Color Differences (JNCDs). Given transmissive (e.g., Active Matrix Liquid Crystal Display (AMLCD)) displays shall continue to create color palette via additive color subpixel gray level; given the number of such gray levels shall continue to be 255 (plus black) for most avionic, vetronic and other commercial applications, the authors anticipate the requirement for a unique set of color gray levels, and to this end propose identifying a statistically reliable set of threshold luminance for transmissive display color channels. Additionally, the authors propose to demonstrate that once individual color primaries are established on a JND basis, any and all combination colors are also unique and distinguishable. Only in this way can 255 gray level transmissive displays be most efficient in delivering their advertised 16.5 million colors and most effective in creating useful results, e.g., color maps, etc. Method of research, to include procedure, equipment, stimuli and test subjects shall be cited. Results of test, to include test subject Fechtner fractions for red, green, and blue, and test subject Fechtner fractions for equivalent color brightness combinations of red, green, and blue, shall be reported.