There is provided an image processing system, which includes: a volume data processor for forming volume data based on image signals and setting at least one frame in the volume data an AGC/LGC parameter setting unit for setting axial gain compensation (AGC) and lateral gain compensation (LGC) parameters based on the frame a gain parameter setting unit for setting a gain parameter based on the frame an amplifying unit for performing AGC/LGC upon image signals based on the AGC/LGC parameters and amplifying the image signals based on the gain parameter a brightness adjusting unit for analyzing intensities of pixels included in the volume data formed based on the image signal performing the AGC/LGC and adjusting the gain, and adjusting brightness of the volume data based on the analysis result and an image processor for forming images based on the frame and the volume data.
