FPGA Implementation for Contrast Enhancement in Images Using Xilinx System Generator

This paper presents novel image contrast enhancement models using Xilinx System Generator (XSG). The proposed models are specifically to enhance the images captured under extremely dark / non-uniform lighting environment as well as for poor contrast environment. To perform the contrast enhancement the proposed design adapts windowing operation by utilizing linear intensity scaling and clipping. By which the proposed models maps a partial range of the grayscale window to the full dynamic range. Thus it brings up the image contrast in a certain grayscale window at the expense of saturating pixels which fall outside the window. For illumination correction, the whole input image is enhanced by the proposed window model 1. And for low contrast enhancement, the input image is split into four non overlapping windows and each window is enhanced by the proposed window model 2. Finally all the windows are mapped to get the output image. These dual models are designed and implemented in Spartan3E (XC3S500E-FG320) and Spartan6-LX9 (XC6SLX9-2CSG324) micro board and their results are compared. The experimental results show that the proposed XSG based designs adapt minimum resources as well as it preserves the quality of the image.