Image enhancement techniques are used to make better visual quality of images. The paper proposed an efficient image enhancement algorithm. The proposed method contains three parts: decimation of image, Bright or dark image decision, and the contrast enhancement. It utilizes spatial decimation method for image resolution reduction to lessen the computational cost. In addition the proposed algorithm employs probability density value to control the sharp brightness in image. Histogram is divided into subgroup regions to enhance the image and the contrast of each region is adjusted separately. The simulation results show that the proposed method has significantly reduces the computational cost and performs better than the conventional method.