Abstract RGB display devices with a white channel have recently been developed to produce a high brightness with low power consumption and enhance the image contrast. However, the addition of a white channel can change the perception of the color represented on the display
device because visual adaptations in human are affected by this addition. Although the measured chromaticity coordinates of a color represented with and without a white channel remain the same, the perceived hue is changed. Therefore, this article presents an analysis of the hue shift phenomenon
and proposes a hue correction method to provide perceptual color matching between a DLP projector with and without a white channel. To quantify the hue shift phenomenon, color patches are generated at equally spaced hue angles and then individually displayed by a projector and on a CRT monitor.
The patches on the CRT monitor are reproduced through device characterization to have an equal colorimetric value with the same patches displayed by the DLP projector with no white channel, so that the patches appearing on the CRT monitor can be used as reference images. Next, the hue for
each patch displayed by the DLP projector with a white channel is adjusted by observers until each patch appears the same as its reference image. These adjusted hues are then fitted into three sets of piecewise polynomial functions, which represent the amounts of hue shift required for perceptual
color matching. After analyzing the hue shift phenomenon, the RGB for each pixel in the input image of the projector is converted to CIELCh color space to obtain the corresponding hue. This hue is then shifted by the proposed polynomial functions which model the hue shift by adding a white
channel. Finally, the corrected hue is inversely converted to RGB in the output image.