Disclosed are method for improving image effect and apparatus thereof, comprising: when a system starts up, acquiring a screen parameter to determine whether an input signal source is an SDR film source or an HDR film source; if it is an SDR film source, performing first image processing to obtain an SDR image, starting up HDR conversion mode; reducing its backlight brightness to pre-set brightness, and displaying current peak brightness pixel or area according to a screen parameter after increasing backlight brightness; if it is HDR film source, performing second image processing to obtain HDR image, closing down HDR conversion mode, before displaying. Thus, a high-grayscale detail performance capacity is improved, achieving an SDR-to-HDR function, a higher brightness range, more picture details, an SDR film source can be played in an HDR television with the display effect of an HDR film source.