ITU-R BT.500-15 (05/2023) is the broadcast-television companion to ITU-T P.910, governing subjective assessment of television picture quality and organized into three parts: overall requirements and when to use which method, the methodologies themselves, and format-specific guidance. It is the home of DSIS (the broadcast name for DCR), the Double Stimulus Continuous Quality Scale (DSCQS), single-stimulus methods, stimulus-comparison (pair comparison), and the continuous-evaluation methods SSCQE and SDSCE. It also owns the canonical viewing-condition rules the multimedia world borrows - peak luminance 70-500 cd/m2, a background at about 0.15 of peak, around 200 lux in a home environment, display calibration with a PLUGE pattern, and viewing distance in picture heights. Its execution machinery is widely used: the at-least-fifteen-observer figure and the informal label, the roughly thirty-minute session limit, the five discarded stabilizing presentations, and the kurtosis-based observer-rejection procedure. When a paper cites BT.500 it is usually for the viewing setup or the DSCQS/DSIS method. Note P.910 now supersedes BT.500's 15-subject figure for multimedia tests.
