Computer Graphics (Spring 2003)

1
Computer Graphics (Spring 2003)

• COMS 4160, Lecture 4 Review session
• Ravi Ramamoorthi

http//www.cs.columbia.edu/ravir/4160
2
Gamma Correction

• A scene is photographed with camera gamma .5
  and displayed on a CRT with gamma 2.4 If we want
  the system gamma to be 1, what gamma correction
  need we apply?
• What does failure to gamma correct do to the
  saturation of colors? That is, if I have a color
  like (1.0, 0.5, 0.5) which is a fairly
  desaturated red, will failure to gamma-correct
  make it appear more reddish (greenish?, bluish?).
  How does this effect vary with how saturated the
  color is originally? Justify your answer
  quantitatively.

3
Intensity and Color

• You have a 300 dpi bilevel printer, and need an
  effective resolution of 75 dpi. How many
  effective shades of gray can you obtain by
  halftoning?
• Write down R, G, B values as appropriate weighted
  summations or integrals over the illumination
  spectrum. Can two different spectral
  distributions of light have the same visual
  sensation or RGB values?

4
Scan conversion

• Give a general incremental algorithm for scan
  converting a polynomial function of the form y
  f(x) assume slope lt 1. How does this relate to
  computing derivatives?