According to the fact that it's more likely to consider the image as the field of knowledge, and the image has the features of intuitivism, ample content, no language limited and convenient for communicating internationally, this article use the case-based reasoning method to decrease the difficulty of obtaining the knowledge, and then propose the case representation method based on image information. We have studied the RGB color model and HSV color model, and then discuss the conversion formula between them. What's more, we have studied the method of extracting the image color characteristics as image case attributes' description, make a model of image case, and then make a case representation on the forest fire early warning image.