Color histogram is a widely used feature in the area of content-based image retrieval. One of the shortcomings of color histogram is that it is sensitive to the location of histogram bin boundaries. Therefore, a novel color histogram calculation technique based on color point coverage is proposed. On the other hand, color quantization approach of HSV color space is studied in this paper. HSV color space is more perceptually uniform in conical form than cylindrical form. Thus, a novel color quantization approach in conical HSV color space is proposed. The results of image retrieval experiment shows that the proposed color quantization approach outperforms the traditional approach, especially with dark background images.