Method and apparatus for changing of brightness of an image

PURPOSE: A method for changing brightness of an image and a device thereof are provided to control brightness without reducing a chroma in a TV, a mobile phone, or a project phone. CONSTITUTION: A brightness changing device changes a color space of an input image(401). The brightness changing device calculates a brightness control rate(403). The brightness changing device corrects the brightness control rate to maintain color balance(405). The brightness changing device multiplies the corrected brightness control rate with linear RGB(Red, Green, Blue). The brightness changing device controls brightness by calculating new RGB(407).