So the source color is the truth, let's pretend we know it's the paper equivalent of #333. The app captures a color and renders it as #444. The user then says

So the source color is the truth, let's pretend we know it's the paper equivalent of #333. The app captures a color and renders it as #444. The user then says, no wait that's wrong, and the app then provides alternatives that are close, let's say #111, #222, #333, #555, #666. In a perfect world, the user will pic #333 and the app will then know the system introduces saturation error of all three colors by 1 so the next time it will compensate for that. Those errors could come from image processing, light sensor calibration, monitor calibration, backlight color temp, ambient color temp, etc. If the user doesn't pick #333 but instead picks a "wrong" color, that's OK, because the value in the app is rendering the color the user wants and perceives as correct, not what happens to be the truth. The difference between a strict functional requirement "app must render the true color" vs a user req of "I want to take a picture of a color and have the color I see render on my screen."