Subjective quality of colour-television pictures impaired by video crosstalk

Quality-grading tests have been made on the effect of video crosstalk on 625-line PAL colour-television signals. With undistorted crosstalk, the worst disturbance was found to be caused by a monochrome pulse-and-bar test signal; subjective impairments of 1 imp and ¼imp are produced by signal/crosstalk ratios of 36dB and 46dB, respectively. When the crosstalk voltage was proportional to frequency, resulting in ‘differentiated’ crosstalk, the worst disturbance was that due to a colour-bar test signal; subjective impairments of 1 imp and ¼imp are produced by signal/crosstalk ratios of 28dB and 34dB, defined in terms of attenuation at the chrominance subcarrier frequency.