Physics 109 Labs and Homeworks (exam 2)

To which colors is each type of cone in the human retina sensitive? use the first letter of each color to indicate that color as follows: red (R), orange (O), yellow (Y), green (G), cyan (C), blue (B), violet (V).

Type I or S cones: V,B,C; Type II or M cones: B,C,G,Y,O; Type III or L cones: C,G,Y,O,R.

What are the 3 psychophysical parameters that define each color?

hue, saturation, and brightness

Which psychophysical parameters does the color triangle display?

hue and saturation, but not brightness

When you shine red light and green light on a screen at the same time, on the same spot, you see yellow. Why don't you see yellow when you mix red and green paint? What do you get when you mix red and green paint?

brown

Are any of the spectral colors within the color triangle and its edges?

yes: R,G,B

In general, where are the spectral colors?

outside the the color triangle, as their saturation is greater

What is the difference between spectral yellow and mixed yellow, obtained by mixing R and G lights?

spectral yellow is more saturated than R+G

On a computer, when using any graphics program, between what values do the amount of red, green, or blue vary?

0-255

How is white represented?

255 255 255

How is sky blue represented?

128 128 255

How is magenta represented?

255 0 255

What are the colors most frequently used in printing?

CMYK

is printing based on subtractive or additive color mixing

subtractive color mixing

Which colors do you need to mix subtractively to obtain R, G, or B, when overlapping filters?

M&Y=R, C&Y=G, M&C=B

What do you see on a screen if all three primary filters are overlapped?

K

When the eye is cyan-adapted, what color does a white wall or screen appear to be, to that eye?

R

You stare for some minutes at a yellow patch on a white background. What do you see when you look at a clean white background?

a B patch, with the same shape and position of the original yellow patch

A lemon is yellow, an apple is red. Which colors are absorbed and which are scattered when these two fruits are illuminated by white light?

The lemon absorbs B and scatters R and G. The apple absorbs B and G and scatters R.