Bias control circuitry for cathode ray tube beam currents

An apparatus including bias control circuitry suitable for use in controlling one or more cathode ray tube (CRT) beam currents, comprising:

• bias circuitry responsive to one or more bias control signals and one or more processed incoming video signals by providing one or more corresponding processed video signals, one or more bias signals for controlling one or more CRT beam currents, and one or more sense signals indicative of said one or more CRT beam currents;
• video signal processing circuitry coupled to said bias circuitry and responsive to one or more incoming video signals and at least a first timing signal by providing said one or more processed incoming video signals, wherein each one of said one or more processed incoming video signals includes a video signal with a vertical blanking interval during which are provided a vertical blanking signal pulse, a sub-black signal pulse and a bias signal pulse;
• and
• control circuitry coupled to said video signal processing circuitry and said bias circuitry, and responsive to said one or more sense signals by providing said one or more bias control signals with each one having a value related to a difference between first and second values of one of said one or more sense signals during at least respective portions of said sub-black and bias signal pulses, respectively.