Extracting and processing video content encoded in a rendered color space to be emulated by an ambient light source, comprising extracting color information from a video signal and transforming the color information through unrendered color space using tristprimary matrices to form a second rendered color space to drive the ambient light source. Video signal decoding into frames can allow extracting average or other color information from an selected screen regions to reduce bitstream load, and negative gamma correction helps prevent garish or inappropriate chromaticities and luminance.