Object-based multilevel contrast stretching method for image enhancement

• Published in: IEEE transactions on consumer electronics 2010-08, Vol.56 (3), p.1746-1754
• Main Authors: Xu, Beilei, Zhuang, Yiqi, Tang, Hualian, Zhang, Li
• Format: Article
• Language: English
• Subjects: Electronics; Frequency domain analysis; Homogeneity; Image contrast; Image edge detection; Image enhancement; Image segmentation; inter-object stretching; intra-object stretching; Merging; Multilevel; Noise; object-based contrast enhancement; Pixel; Preserves; Stretching; Studies
• ISSN: 0098-3063; 1558-4127
• DOI: 10.1109/TCE.2010.5606321

The purpose of image enhancement is to improve the perceptibility of information contained in an image. Since the human visual system tends to extract image structure, enhancing the structural features can improve perceived image quality. This paper proposes an object-based multilevel contrast stretching method to enhance image structure. The method first segments the image into its constitute objects, which are treated as image structural components, using morphological watersheds and region merging; then separately stretches the image contrast at interobject level and intra-object level in different ways. At interobject level, an approach of stretching between adjacent local extremes is used to adequately enlarge the local dynamic range of gray levels between objects. At intra-object level, the uniform linear stretching is used to enhance the textural features of objects while maintaining their homogeneity. Since the proposed method directly operates on the object, it can avoid introducing ringing, blocking or other false contouring artifacts in structural appearance; moreover, it can effectively suppress over emphasizing of noise and roughly preserve the overall brightness of the image. Experimental results show that the proposed method can produce enhanced images with more natural appearance in comparison with some classical methods.