FPGA Implementation of Gamma Correction using a Piecewise Linear Approach for a Small Size Endoscopic Camera

Abstract

A gamma function is essential for adjusting the response of any display device. In the case of endoscopy, it is even more important because for endoscopy it is not only the satisfaction of the user but the diagnosis of patient’s problems that could lead to life and death decision sometimes. In this paper, a technique of approximating the gamma function is applied using a piecewise linear method. It has 10 bits input and output pixels of color (RBG) channels. VHDL is used to describe the function and implemented in a Spartan 6 FPGA to achieve high computation and parallel processing. It was tested on a small endoscopy camera called NanEye. The system has 31 reconfigurable gamma function values from 1 to 4 with 0.1 intervals. It has a small footprint in terms of memory and no specialized DSP processor. The average mean absolute error of the implemented solution is 2.1747. The system can process up to 750 million pixel components per second in a Spartan 6 FPGA.