Grayscale, gamma, dithering
CS 248 - Introduction to Computer Graphics
Autumn Quarter, 2002
Lecture notes for Tuesday, October 8 (second half of class)
Table of contents:
IV. So how many bits do we need per pixel?
Click here to see a
demo of quantization levels.
- Synthetic images: 6-8 bits.
Some people claim they need more.
- Quantization in a linear perceived brightness space:
5 bits looks acceptable (at least for this example)
- Scanned/painted images: 5 bits usually ok.
Why? Noise breaks up contouring artifacts.
- Antialiased edges: 3 bits suffice!
Why? Shorter distance, so contours are compressed.
This example was also hand drawn, which breaks up contours.
Make sure you view this demo on a gamma-corrected monitor,
as the instructions say.
The rest of this lecture will be covered on Thursday, Oct. 11
Copyright © 2002 Marc Levoy
October 7, 2002 08:40:37 PM