When looking at spectral reflectance curves produced from different objects, it can be seen that:
WHITE
White is 100% reflectance at all visible wavelengths from 400 to 700 nm.
BLACK
Black is 0% reflectance at all visible wavelengths from 400 to 700 nm.
GRAY
Therefore, "straight lines" with equal reflectance at all visible wavelengths from 400 to 700 nm are shades of gray. If the reflectance is nearer to 100%, this is a light gray. Likewise, if the reflectance is nearer to 0%, this is a darker gray.
COLORS
Not until there is deviation from this "straight line" do we see various colors.
Blue reflectance curve |
Here we see a blue reflectance curve. It has reflectance in the blue region of the spectrum (400-500 nm) and very little or no reflectance in the green (500-600 nm) and red (600-700 nm) regions of the spectrum.
Green reflectance curve |
Here we see a green reflectance curve. It has reflectance in the green region of the spectrum, but very little or no reflectance in the blue and red regions of the spectrum.