Kathodenstrahlröhretreiber mit Schwarzpegelabgleich am Eingang

In a video display system including a cathode ray tube (CRT 18) as a display device and video output amplifiers (12R; 12G; 12B) for amplifying relatively low level red, green and blue video input voltages (R; G; B) to produce respective relatively high level video output voltages suitable for application to the CRT, a "black tracking" circuit (RR, RG, RB, CC, RC) is coupled to the inputs of the video output amplifiers. Voltage to current converters (10R; 10G; 10B) are utilized as preamplifiers for the video output amplifiers. The "black tracking" circuit includes terminating resistors (RR; RG; RB) connected at one end to respective outputs of the voltage to current converters for converting output currents of the converters to respective ones of the low level video input voltages, and a common resistor (RC) connected between the other ends of the terminating resistors and a signal ground point. A filter capacitor (CC) is connected in parallel with the common resistor. A common "black tracking" voltage (EC) representative of the average picture level of a reproduced image is developed across the common resistor and, as a result of its connection to individual ones of the terminating resistors, is added to each one of the low level video input voltages at the inputs of respective ones of the video output amplifiers.