A Subfield Coding Algorithm for the Reduction of Gray Level Errors Due to Line Load in a Plasma Display Panel

Displayed gray level of a plasma display panel (PDP) is often different from the intended target gray level due to the variation of the line load (the number of on-cells on a scan line). The conventional gray level generation algorithm does not take this difference into consideration and may deteriorate the displayed image quality. In this paper, luminance ratio variations that depend on the line load are formulated as the third-order regression equations for red, green and blue colors, respectively. Based on these equations, this paper proposes a new gray-level generation algorithm to reduce gray-level errors caused by the variation of the line load. The proposed algorithm performs the conventional algorithm three times with new weight vectors (i.e., the expected gray levels of subfields) adjusted based on the detected error of the previous run of the conventional algorithm. Simulations and experiments with a 50-in PDP show significant error reductions, including a 75.6% improvement of the mean absolute error evaluated with nine video sequences.