antialiasing - department of computer science and ...olano/class/435-08-2/antialiasing.pdfno...
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Antialiasing
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Visual artifacts - Jagged lines and edges - High frequencies appearing as low - Small objects missed - Texture distortions - Strobing and popping - Backward movement
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Two basic stages - Sampling - Reconstruction
Assuming discrete sampling
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Shannon's sampling theory (1D): - A band limited signal f(t) with cut off frequency wF
may be perfectly reconstructed from its samples f(nT0) if 2π/T0 >= 2wF
- wF == Nyquist limit Alternatively:
- A signal can be reconstructed exactly from samples only if the highest frequency is less than half the sampling rate
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Two samples of the same sine wave
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Regular supersampling Jittered supersampling Adaptive supersampling Stochastic sampling
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Reconstruction: recreate a continuous signal from a set of samples
Tasks of reconstruction filter - Remove extraneous replicas of signal spectrum - Pass the original signal base unchanged
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B-Spline Filter
Mitchell-Netravali Filter
Gaussian Filter
Catmull-Rom Filter
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