Color Descriptors from Compressed Images

The success of international standardization of image compression techniques resulted in a consequent increase in the number of images and videos in various media publications, web publications, etc. There was a need for a system to classify and manage the content of those compressed images and videos. The visual descriptors describe characteristics such as color, shape, texture, motion, etc. Color is one of the most important features for describing the visual content. Color histograms are one of the popular methods for indexing images. Most approaches for color based retrieval convert the color space to the more tractable HSV for similarity matching. JPEG, MPEG and H.26x are some of the many still and moving picture standards developed. Following the successful development of MPEG-1, MPEG-2 and MPEG-4 standards, a new standard called MPEG-7 was formed to describe multimedia content. Compression standards like JPEG store images in the YCbCr color space. MPEG-7 has standardized a set of color descriptors for this purpose. (1,2,3)