CORDIC Based SSIM Computation in FPGA

Abstract

Images may be distorted by imaging system or by transfer it from one system to another or to process for different application. So, it is important to calculate the quality of the image before presenting to the viewer. This distortion measured by some traditional parameters like PSNR, SSIM and RMSE. But, SSIM is well established method, provides nearly same result as human visual system. The distortion in the image has been calculated using SSIM in this work. The compressed SSIM has been measured in this work in frequency domain in Discrete Cosine Transform (DCT) dictionary. Images are 2D data matrix, so this work aims to calculate 2D DCT using 1D DCT. 1D DCT is calculated by well-established CORDIC algorithm. The CORDIC algorithm is sequential in nature. But can also be implemented parallel using FPGA, as different processes in FPGA produces output simultaneously. The output of VHDL core is compared with MATLAB inbuilt SSIM function’s output.