US Patent 7443538 Method of controlling printed line quality

A printer embodied rendering algorithm for detecting and configuring positive and negative thin lines to be rendered such that when a bright-colored thin line on a dark background (negative thin line) is rendered and the result is stored in an RGB buffer in a printer system, the thin line thickness is increased only when the brightness of the line color is higher than a predetermined threshold value and the thin line thickness is smaller than a predetermined threshold value. According to the rendering algorithm, it is possible to prevent a negative thin line from disappearing or becoming thinner without increasing a positive thin line thickness, thereby improving the visibility of the thin line.