Image retrieval based automatic grayscale image colorization

Colorization is an appealing area in the world of image processing. It has been used to increase the visual appeal of images such as old black and white photos, classic movies or scientific illustrations. Also, It has been very important in color image compression and video compression. Colorization, the task of coloring a grayscale image or video, involves assigning an intensity or luminance from the single dimension to a quantity that varies in three dimensions, such as red, green, and blue channels. Different colorization techniques are prevailing like hand coloring, semi automatic coloring and automatic coloring. Hand coloring and semi automatic coloring require intensive and perfect human interference. We are introducing a methodology for adding color to grayscale images in a way that is automatic and require little execution time. Towards this aim, a colorful image of the similar content as the grayscale image is taken, as an input source image by means of different image retrieval techniques. Then, the best matching source pixel is determined using luminance matching technique, for each pixel of the target grayscale image. Once a best matching source pixel is found, its chromaticity values are assigned to the target pixel while the original luminance value of the target pixel is retained.