An Analysis and Implementation of Natural Image Enhancement Method

Digital image enhancement is to improve the appearance of images to human viewers. This is one of extremely difficult issues in image processing. The NECI algorithm (Natural Enhancement of Color Image) is a robust and effective approach for color image enhancement. The core of this algorithm is Retinex model, a simulation model of human color vision. A fully framework for enhancement process is composed of four main steps: global tone mapping, Retinex-based local contrast enhancement, histogram rescaling, and texture enhancement. The experimental results on different types of natural images show that the proposed algorithm not only preserves the ambience of image but also avoid side effects such as light condition changes, color temperature alteration, or additional artifacts, etc which lead to unnaturally sharpened images or dramatic white balance changes. In the output color images, no additional light sources are added to the scene, or no halo effect and blocking effect are amplified due to over-enhancement. Moreover, all parameters are image-dependent so that the process requires no parameter tuning. Source Code This paper is related to an image enhancement, designed to enhance the color image naturally without any parameters. The software is written in C and can be compiled with any C/C++ compilers. The codes are available at the web page of the article.

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