Real-time, color image barrel distortion removal

This paper describes a new hardware architecture for barrel distortion correction in a color video stream. Such distortion is omnipresent in images acquired with a large field of view optics: wide-angle or fish-eye lenses. The designed platform is composed of a standard image sensor, a USB video class ASIC chip, a low cost FPGA and a SDRAM memory chip. Image processing algorithms are implemented in the FPGA, which is inserted between the sensor and the ASIC. The FPGA is connected to an external SDRAM in which a frame buffer is implemented. Barrel distortion is modeled using a polynominal relationship between corrected and distorted image spaces. Combinatorial logic circuit at the frame buffer output validates correct ordering of luminance and chrominance bytes in the data stream. The proposed design is capable of removing geometric distortion from 640 x 480 pixel images at the rate of 30 frames per second. Colors in reconstructed images are within Delta E = 2 from the originals in the CIELab color space.