Methods Anti-Aliasing Super Sampling Multiple sample points across a finer grid to determine pixel intensity High Resolution Computation Low Resolution display Obtain intensity information from multiple points that contribute to intensity of pixel. Run Bresenham’s algorithm on microgrid. Set pixel intensities Aliasing Distortion of information due to low frequency sampling Under sampling Anti-aliasing Compensates for this distortion If pixels have more than one intensity Vary the intensity levels to compensate

SuperSampling Plot (0,0 to 2,1) Δx = 2, Δy = 1 Multiply both directions by 3 (adding a 3x3 grid) Plotting (microgrid) Δx = 8, Δy = 4 P0 = 2Δy – Δx = 0 0 0 K PK XK+1 YK+1 0 0 1 1 1 -8 2 1 2 0 3 2 3 -8 4 2 4 0 5 3 5 -8 6 3 6 0 7 4 7 -8 8 4 If PK < 0 plot XK+1, YK PK+1 = PK +2Δy Else plot XK+1, YK+1 PK+1 = PK +2Δy -2Δx

Anti-aliasing Normal weighting Anti-aliasing Weighted 1 2 1 2 4 2 1 2 1 1 7 3 1/3 1 7 2/3 7 3 At most 3 micro-pixels filled 4 levels of intensity (including off) 3 = full, 2 = 2/3, 1= 1/3, 0=0