Answer:
relative luminance
Step-by-step explanation:
From the question we are informed about Madeline who is an interior designer. When she chooses a new color for her client's walls, she always checks the swatch against different colored objects in the room. Madeline in this case, is aware of how colors change because of relative luminance.
Relative luminance can as well be regarded as Perceptual constancy, This can be explained as amount of light that can be reflected by an objects on its surroundings. Perceptual constancy is one that visualize familiar objects as one having a consistent color, even though a case whereby light changes the court arises. Relative luminance can be regarded as one that goes in same way as photometric definition of luminance, here Relative luminance has normalized values of 1 or 100 with respect to reference white.