Image enhancement via reducing impairment effects on illumination and reflectance components

In this paper, a new approach is presented for improving image quality which it provides a new outlook on how to apply the enhancement methods on images. Image enhancement techniques may be performed based on the illumination, resolution, or distribution. In image capturing, issues such as the illumination of the scene and reflectance of objects affect on image captures. The effect of each of these issues on the resulting image can be considered as a separate component or image and they can be reviewed using homomorphic filter where the original image is decomposed into illumination and reflectance components. Generally, the pixels value of an image is proportional to the illumination of point in the scene and the reflectance of the object. Based on this, impairment in the image may be due to each of the illumination or reflectance images. In this paper it is shown that various types of impairments have a different effect on the illumination and reflectance of image components. Studies show that impairment effect on an image depending on the type of the impairment on one component is different to another component. Unlike conventional methods which dose enhancement process on the original image for any type of impairment, in this paper it is suggested that based on type of impairments, enhancement of image is done on corresponding components after image decomposition into illumination and reflectance components. Hence final improved image can be achieved using image components that they include improved component. Results of this research show that image components enhancement has better results comparing to directly enhancement of original image to eliminate the image impairment. In this paper, it is used the Yale Face B database for facial images and different gray level images for non facial images.