The U.S. cotton classification system has been undergoing significant change, moving from human classing to the utilization of precise instruments. Along with this trend, the current research is an effort to develop a new computer vision system to measure detailed trash and color attributes of raw cotton. The system primarily consists of a color CCD camera, xenon flash light, and customized software. In this paper, we will introduce a new trash and spot identification method, multi-dimension thresholding, and the methods for characterizing size, spatial density, shape, and color of trash and spots present in cotton samples. The trash and color measurements of twelve cotton samples, including statistical data and distribution curves, will be reported. The results obtained from this system will be compared with those obtained from other instruments such as Spinlab and Motion Control HVI machines and Minolta Chroma Meter CR-210. The influences of trash and spots on cotton color values will be investigated.