A display driver circuit configured to be shared by three grey-scale voltage generators to be respectively used with red (R), green (G) and blue (B) colors. In particular, two of the three grey-scale voltage generators share first and second resistor strings, gamma voltage selectors, and gamma adjustment buffers provided in the other grey-scale voltage generator, thereby reducing the size and power consumption of the display driver circuit. Also, when only a single grey-scale voltage is output, it is possible to deactivate the grey-scale voltages provided by two of the grey-scale generators and further reduce power consumption.