David, It comes back to my "idea" of "threshold"; what's the 'criteria' that makes two colors appear "different" to a 'normal observer'? It has to be 'measurably' different otherwise, we're going to argue until the cows come home. / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca@lists.apple.com> On Behalf Of David Scharf via colorsync-users Sent: Monday, January 6, 2020 7:32 PM To: Andrew Rodney <andrew@digitaldog.net>; david@scharfphoto.com; Florian Höch via colorsync-users <colorsync-users@lists.apple.com> Cc: David Scharf <electronman@roadrunner.com> Subject: Re: NEC PA271Q "Native" chromaticities Hi Andrew, My point was that when there are colors separated by an extremely small increment, they may be indistinguishable from each other and we may may perceive them to be the same color--so not invisible but visible--just not perceptually different. Seems like we are making two different valid arguments. DAVID SCHARF PHOTOGRAPHY *DAVID SCHARF PHOTOGRAPHY* Scanning Electron Microscopy http://www.electronmicro.com This email sent to graxx@videotron.ca