Histogram Equalization variants preserving non uniform illuminated images

It is always a big concern to improve the condition of an image when it comes to fine details of under and over-exposed images. To enhance the fine details of images, an optimal enhancement technique is required. A lot more techniques are suggested in past. Among them, histogram equalization (HE) would be considered as best. The histogram is broadly used to amplify the contrast of an image for its clarity and directness. The main drawback of this technique is the flattening effect in graph that uniformly distributes the gray level. Several modifications of the technique have been made to overcome the barriers of the traditional histograms and enhance the non-uniform illuminated images. This paper provides insight into histograms and their versions. Moreover, the proposed paper proceeds with checking the quality parameter of techniques. The paper concluded the optimal method to be implemented on non-uniform illuminated images using the histogram equalization method.