OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 4.3, Eighth Edition

Antialiasing High Frequencies

Aliasing does not occur until we attempt to represent a continuous image with discrete samples. This conversion occurs during rasterization. There are only two choices: either don’t have high-frequency detail in the image to render, or somehow deal with undersampling of high-frequency detail. Since the former is almost never desirable due to viewing with a variety of scales, we focus on the latter. Therefore, our attempts to mitigate its effects will always occur in the fragment shader. They will still include both tools of removing high-frequencies or sampling at higher rates, but both are done after rasterization, where we can compare the frequencies of detail present in the image with the frequency of the pixels. ...