ABSTRACT
Aliasing is an artifact of digital images; it occurs when an image contains detail smaller than the pixel pitch. This chapter starts with an intuitive look at how aliasing can occur in sampled images. Then, the history and the description of antialiasing filters are presented in Section 4.2. Nyquist diagrams, which provide a way to analyze and visualize antialiasing filter requirements, are discussed in Section 4.3. Section 4.4 discusses the modulation transfer function, a measure of system resolution, because the occurrence of aliasing is dependent on system resolution. Lens modulation transfer function is the focus of Section 4.5. Sections 4.6 and 4.7 present a brief description of convolution and Fourier analysis. Many of the details of sampled imaging systems become apparent when analyzed in the frequency domain; therefore, Section 4.8 steps through the sampling process in the spatial and frequency domain. Subsequently, reconstruction issues are discussed in Section 4.9. Finally, antialiasing filter construction and testing are the central topics of Sections 4.10 and 4.11, and conclusions are presented in Section 4.12.
