Grayscale image formats for edge detection and for its FPGA implementation

Abstract

The aim of this paper is analysis of image formats used for FPGA implementation of edge detection methods. All cameras used in FPGA applications give Raw RGB output video format, some cameras provide also YUV, YCbCr, RGB565/555 or compressed JPEG formats. If the FPGA circuit has limited number of configurable logic blocks (CLB) the JPEG format seems to be good solution how to increase the size of the processed image. On the other hand, using an image with lossy compression can more or less affect the overall result of image processing. The first goal of this paper is to show whether lossy image compression can affect the quality of edge detection. The results presented in this article show that lossy image compression can impair the efficiency of edge detection by up to six percent. Many researchers have proposed FPGA implementation of some edge detection methods. Usually their first step is RGB to grayscale conversion because they use edge detection methods for grayscale images. The second goal of this paper is to show that a performance of FPGA implementation can be improved if YUV, YCbCr or Raw RGB camera output formats are used instead of RGB format.