The static and dynamic characteristics of smoke are developed for extracting smoke pixels of an image and effective smoke detection. In static characteristic, a chromaticity-based analysis is employed to extract grayish pixels in the moving region from a monitored area. Then, a circumference-based disorder measurement in dynamic characteristic is developed to obtain the smoke pixels from the grayish pixels. To enhance the reliability of alarming, a fuzzy system is introduced to judge if the smoke will spread out by checking its growth-rate.