In order to accurately divide the flame zone from the background and extract the flame contour of a flame picture. This article proposes a algorithm of flame contour extraction based on YIQ color space. This algorithm uses the color and brightness features of flame,by a large number of experimental observation,in the YIQ color space,to obtain firstly the mean value of Y and I component,then,the best threshold of Y and I by Histo-gram method and Iterative Method,and aligning treatment Y and I threshold combined with their mean value.At last,it uses the canny algorithm to extract contour of Bina...