More on FAQ #886
886. What about tonal rendering when converting colors to grayscale?
When converting a color photograph to grayscale, darker colors obviously have to be rendered with darker gray tones and lighter colors with lighter gray tones.
To reverse the tonality of a photograph is to disqualify the result from P7.
When two colors render equally in grayscale (red apples in a green bowl, for example, or green apples in a red bowl) most editors applying rinairs would likely accept grayscale versions of the image that undergo non-radical tonal variations that help distinguish the apples from the bowl.
By the same token, a photograph would be disqualified by P7 if the conversion to grayscale were used to eliminate the depiction of forms and shapes.
An example of this would be if the color sliders were adjusted during a grayscale conversion to make some graffiti the exact same tonality as the colored wall on which it was painted, thereby rendering the graffiti virtually invisible in the grayscale version.