Research And Implementation Of Color Image Enhancement Algorithms

Recent years, the color image information has been widely used in various fields,and got a great deal of attention in digital image processing with the constantly improving multimedia technology. Color image enhancement, is a very important pre-processing, and played a crucial role in improving the color image quality and subsequent image analysis, which makes color image enhancement algorithm become a hot spot. Unlike the gray-scale image enhancement, the process of color image enhancement, not only need to strengthen the determination and identification effect of image,but also to avoid color distortion caused by image enhancement.Recovery as the main idea of this algorithm in accordance with the color image-the intensity image-color image restoration, that is to say it will calculate the intensity image(2D grayscale image), and then enhance the intensity image, finally restore the color image after enhancement. The method of intensity image acquisition, the selection of the intensity enhancement processing and color space, determine the effect of the color image enhancement together. Calculation of the intensity image of the color image using a maximum value method, to ensure that the intensity image of the extraction accuracy and to avoid overflow of pixel values in the color recovery process; During the intensity image enhancement processing, an improved algorithm has been approached which is the dual histogram dynamic range equalization approach, the enhanced image obtained more image details while enhancing the image; color recovery process using a proportional operation for each channel of R,G,B. The whole process of the algorithm has avoided the color space conversion of common algorithms,and improved the efficiency of the algorithm, at the same time got a better hue preserved, which implements a fast hue preserved color image enhancement algorithm.In summary, the research work of this paper are:(1) The paper has described the basic image enhancement methods of two-dimensional gray-scale image to clarify the various methods of the enhancement principle and implementation process, and as a color image enhancement algorithm based, learned about several commonly used color spaces, and gave a detailed discussion of several commonly used color space for color image enhancement method.(2) Then it analyses the advantages and disadvantages of performance about a variety of color image enhancement methods in the effect of enhancement, algorithm complexity and performance on hue preserving, the advantages and disadvantages of performance, and propose an improved histogram processing method, the dual histogram dynamic range equalization approach which applied to color image enhancement processing to achieve a fast hue preserved color image enhancement algorithm. This algorithm has taken into account the color preserving, the algorithm efficiency and the range of pixel values.(3) Through comparing about the experiment of these algorithms, and making an analysis on subjective image effects and several effective objective performance parameters, the color images after processed by the proposed algorithm have not only got the clear color images,but also achieved better color preserving effect. At the same time,the computing efficiency has been improved.The proposed algorithm has certain advantages. Finally, the proposed algorithm is applied in low-light image enhancement of a case study in traffic scene.