Measurement and analysis of color shift behavior at image pattern edges projected by raster-scan RGB mobile laser projectors

Color shift behavior at the edges of white-and-black line patterns was measured and analyzed for three raster-scan mobile projectors using the three-primary-color (red, green, blue) laser diodes. The 2D data of the line patterns projected on a standard diffusive reflectance screen were captured by a speckle measurement device for analyzing the effects of both the color speckle noise and the edge color shift. The color speckle noise usually blurs the underlying behavior of the edge color shift. To extract the underlying color shift, the color speckle noise was minimized by opening the iris of the speckle measurement device, and the residual noise was averaged. The color shift trajectories were successfully plotted with perfectly high visibility in the color space consisting of CIE1931 chromaticity coordinates and normalized illuminance. As a result, each of the three projectors showed a unique edge color shift behavior with a unique trajectory in the color space, depending on the spatial behavior of red, green, blue laser beams or the temporal response of red, green, blue laser diodes.