For improving the brightness decay of a display due to its aging, a non-volatile memory such as Flash can be used to store a brightness accumulation value of each point of the display, and each point can be compensated for its brightness accordingly. However, the non-volatile memory suffers from incorrect write-in data or temporary power disconnection, and thus the error will exist all the time to make the display non-even. Hence, the present invention uses a multiple data backups and CRC error detection, plus new/old data comparison to protect data the non-volatile memory from incorrect brightness compensation value so as to uniform the brightness of the display.