Organic light emitting display device and driving method of the same

An organic light emitting display device includes: a display panel including a plurality of pixels; a power source configured to provide a high power voltage and a low power voltage to the pixels; a data driver configured to provide a data signal to the pixels through data lines; a scan driver configured to provide a scan signal to the pixels through scan lines; a timing controller configured to provide control signals that control the power source, the data driver, and the scan driver; and an image processor configured to receive an HDR image signal by every frame, calculate an on-pixel ratio (OPR) that represents a ratio of a number of the pixels that turn on based on the HDR image signal to the number of all pixels included in the display panel, and control a brightness of the pixels that turn on based on the on-pixel ratio.