1. 168 471 Computer Graphics, KKU. Lecture 9
Antialiasing
jaggies
digitized
Analog line
Digital line: aliasing occurs
Aliased 'W'
Antialiased 'W'
Computer Graphics, KKU. Lecture 9

2. 168 471 Computer Graphics, KKU. Lecture 9
Antialiasing
What anti-aliasing attempts to do is, using mathematics, fill in some of the digital system with colors that are in-between the two adjoining colors. In this case a medium gray would be between the black and the white. Some gray squares placed in the grid might help soften up the "jaggies"
Computer Graphics, KKU. Lecture 9

3. 168 471 Computer Graphics, KKU. Lecture 9
Antialiasing
Computer Graphics, KKU. Lecture 9

4. Unweighted Area Sampling
Intensity is proportional to the amount of area covered.
Defining the box weighting function which has volume of 1 (Imax).
Determine the overlap volume Ws [0, 1].
Computer Graphics, KKU. Lecture 9

5. Weighted Area Sampling
Computer Graphics, KKU. Lecture 9

6. Antialiasing in Practice
Use of low pass filter by summing products between the mask coefficients and the intensities of the pixels under the mask.
For w which is a 3x3 mask, the response R at the center of the mask is R = w1z1 + w2z2 + … + w9z9
mask R
mask R
Computer Graphics, KKU. Lecture 9

7. Antialiasing in Practice
(b)
Computer Graphics, KKU. Lecture 9