Antialiasing (often shortened to "AA") is a broad term referring to various techniques for removing the aliasing effect in an image (harsh pixelated edges or “jaggies”).
Unlike some renderers, Corona does not provide direct control over the maximum and minimum number of samples per pixel; rather, being a progressive renderer, Corona renders the image in a series of passes. Each pass increases the image quality by accumulating antialiasing samples, until a certain number of passes (given by the pass limit) or noise level has been reached, or the user manually stops the rendering (by pressing the stop or cancel button). The current number of rendered passes is reported in the VFB stats tab, render stamp (if enabled), and the Rendering dialogue.
Note: we can assume that each pixel receives one sample per pass, however with adaptivity, this is automatically adjusted per pixel to focus rendering effort where it is most needed.
You can fine-tune the balance of computation on antialiasing and GI sampling using the "GI vs. AA balance" and/or "Light Samples Multiplier" controls, however in most cases these settings can be left at their defaults.
You can also select a specific image filter and control its width. You will find it in Render Setup > System > Frame Buffer > Image filter.
Enabling High-quality image filtering is equivalent to using a Tent filter with width 2, however, it will produce substantially higher quality results at a lower number of passes. It is recommended to use the default settings of the image filter for the best rendering speed and quality.
Note: Setting the image filter to "None" will not disable antialiasing, rather it will then use the so-called box filter, which is technically the worst antialiasing filter (used by most renderers). To disable antialiasing completely, see: How to disable antialiasing?
Corona image filtering settings should be left at their defaults for best rendering performance and image quality.