One of the things that distinguishes FractalViewer from other programs that generate fractal images is that it anti-aliases the images it generates. Anti-aliasing is a process that improves the image quality in areas of the image that are varying too fast to be well represented by the pixels that cover that area. These areas occur frequently in fractal images, so anti-aliasing makes a big difference to the image quality.
The level of anti-aliasing used by FractalViewer is set on the Options panel, which can be brought up from the View/Options... menu command.
Image generated with no anti-aliasing
FractalViewer uses an adaptive anti-aliasing technique to speed up the process. This works by only anti-aliasing pixels that are different to any of the adjacent pixels. A pixel that is selected for anti-aliasing is anti-aliased using a brute force approach, by calculating a number of sub-pixels within the pixel, and averaging these. The number of sub-pixels used can be set by the user on the Options panel, from 2x2 sub-pixels up to 8x8 sub-pixels.
Anti-aliasing can therefore be fairly slow, but FractalViewer will always show the aliased image first, and then switch to the anti-aliased image automatically once it is ready.