关键词: 图像增强, 图像分割, 形态学分水岭, 区域合并, 对比度拉伸

Abstract: To solve the problems of the ringing, blocking artifacts and the excessive noise amplification in local image enhancement, an object-based multilevel contrast stretching method was proposed. First, segment the image into its constitent objects by using morphological watersheds and regional merging; then, separately stretch the image contrast at inter-object level and intra-object level in different ways. At inter-object level, an approach of stretching between adjacent extrema was adopted to adequately enlarge the local dynamic range of gray levels between objects; at intra-object level, the linear stretching approach was adopted to enhance the textural feature of the object and keep its appearance. Experimental results show, besides enhancing the image structure, the proposed method can effectively avoid ringing, blocking artifacts, restrict excessive noise amplification in smooth areas and preserve the overall brightness of the image, thus can provide the enhanced image with natural appearance.

Key words: image enhancement, image segmentation, morphological watershed, region merging, contrast stretching