Compression storage of images with an effective annular zone

In 3D measurement of complex deep-hole inner profile with ring-structured-light, the effective area of the original images is an annular zone, only a small portion of the whole. A new image compression storage method has been proposed, where only the image information of the effective annular zone, denoted by T, is stored. The method consists of the following procedures. Find the center and the inner/outer radii of T, decompose T into a series of concentric circles of one pixel wide, arrange the intensity data of all pixels on each concentric circle according to a definite order, compress the data sequence to make the image file shorter. Experiments show that this method has a large compression ratio. Much storage space can be effectively saved when there is a great number of such images should be stored.