Starting in MATLAB R2014b, figures use an antialiasing technique to reduce the appearance of jagged lines. However, the smoothing technique sacrifices some sharpness for smoothness and, in some cases, lines might appear fuzzy. To turn off antialiasing, set the GraphicsSmoothing property for the figure to 'off'. For example:
These images show the difference between two lines, one with GraphicsSmoothing set to on and one with GraphicsSmoothing set to off.
If your graph contains mostly vertical or horizontal lines that appear uneven in thickness, use the AlignVertexCenters property to eliminate the uneven appearance. By default, this property is set to 'off'. To eliminate the uneven appearance, set the AlignVertexCenters property for the lines to 'on'.
For example, create a plot of horizontal lines and set the AlignVertexCenters property for all of the lines to 'on';. Keep the GraphicsSmoothing property set to 'on' (the default).
p = plot([1:10; 1:10],[1 2])