Contrast enhancement based on discriminative co-occurrence statistics
Autor: | Sun Yongqing, Xiaomeng Wu, Kunio Kashino, Takahito Kawanishi |
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Rok vydání: | 2020 |
Předmět: |
Brightness
Pixel Computer Networks and Communications Computer science business.industry media_common.quotation_subject ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION Intensity mapping 020207 software engineering Pattern recognition 02 engineering and technology Discriminative model Hardware and Architecture Histogram 0202 electrical engineering electronic engineering information engineering Media Technology Contrast (vision) Artificial intelligence business Software Histogram equalization media_common |
Zdroj: | Multimedia Tools and Applications. 80:6413-6442 |
ISSN: | 1573-7721 1380-7501 |
Popis: | Despite recent advances in contrast enhancement, it remains difficult for existing methods to simultaneously achieve consistent improvements in image brightness and contrast in both low-light and normal-light images. To address this issue, we revisit 2D histogram equalization methods and extend them to accommodate more diversified and poor lighting conditions. The extension is based on the observation that the contrast needs to be improved by increasing the intensity difference between spatially neighboring pixels, while the degree of increase should be proportional to the difference in their reflectances. On the basis of this observation, we propose to embed the inter-pixel contextual information of image reflectance into the 2D histogram of intensity co-occurrence. An intensity mapping function can thus be derived by solving optimization problems formulated with the 2D histogram, leading to two novel contrast enhancement methods. Qualitative and quantitative evaluations on more than 600 images showed that the proposed methods are superior to state-of-the-art contrast enhancement methods. It was also shown that the reflectance of an image provides important visual information on the significance and objectness of local image areas. Using this reflectance as a clue, the degree of contrast enhancement can be adaptively derived to achieve sufficient brightness improvement in low-light images and to avoid excessive enhancement in normal-light images. |
Databáze: | OpenAIRE |
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