WINDOW-DEPENDENT BRIGHTNESS/TINT CONTROL FOR VIDEO DIGITAL-TO-ANALOG CONVERTERS

摘要

A display control circuit controls the outputs of the three video DACs (12) of an RGB monitor on a window-to-window basis to enable the display of motion video and text on the same screen with different brightness and/or tint. A digital overdrive signal (30), synchronized to the video DAC digital inputs (15), is used to enable added DAC elements (20) for the pixels in the video windows only. Stored digital instructions (28) determine how many and which added DAC elements are enabled by the overdrive bit(s). By storing different instructions for each of the three video DACs, the circuit may also provide window-dependent tint control. As many different values of brightness and tint may be available as desired by increasing the number of synchronized input enabling bits and the number and strength of the added DAC elements.