Aliasing is caused by finite addressability of the CRT.
Approximation of lines and circles with discrete points often gives a staircase apprearance of "Jaggies".
Desired Line
Aliased rendering of the line
Aliasing can be smoothed out by using higher addressability.
If addressability is fixed but intensity is variable, use the intensity to control the address of a "virtual pizel". Two adjacent pixels can be used to give the impression of a point part way between them. The perceived location of the point is dependent upon the ratio of the intensities used at each. The impression of a pixel located halfway between two addressable points can be given by having two adjacent pixels at half intensity.