PURPOSE: To adjust the white balance automatically by using a correction function to convert a drive voltage of each of R, G, B cathode ray tubes in a projection type color television receiver.

CONSTITUTION: A drive voltage of each of cathode ray tubes 1R, 1G, 1B varies with optional several tens of stages of levels from a low light to highlight, and a brightness of a window pattern of the R, G, B projected on a screen 3 is measured by an optical measurement device 10. Then data of a drive voltage versus brightness characteristic are stored in a RAM 18. A luminous characteristic arithmetic operation circuit 20 uses the data to calculate a correlation function correction each brightness characteristic of the R, G, B and a drive ratio. A video signal processing circuit 17 generates a correction drive signal by using the correlation function data to control the drive voltage from a low light to a highlight so as to obtain a uniform white color.