Local Contrast-Based Pixel Ordering for Exact Histogram Specification
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| Title: | Local Contrast-Based Pixel Ordering for Exact Histogram Specification |
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| Authors: | Kohei Inoue, Naoki Ono, Kenji Hara |
| Source: | Journal of Imaging, Vol 8, Iss 247, p 247 (2022) |
| Publisher Information: | MDPI AG |
| Publication Year: | 2022 |
| Collection: | Directory of Open Access Journals: DOAJ Articles |
| Subject Terms: | exact histogram equalization, exact histogram specification, Gaussian filter, contrast enhancement, pixel ordering, Photography, TR1-1050, Computer applications to medicine. Medical informatics, R858-859.7, Electronic computers. Computer science, QA75.5-76.95 |
| Description: | Histogram equalization is one of the basic image processing tasks for contrast enhancement, and its generalized version is histogram specification, which accepts arbitrary shapes of target histograms including uniform distributions for histogram equalization. It is well known that strictly ordered pixels in an image can be voted to any target histogram to achieve exact histogram specification. This paper proposes a method for ordering pixels in an image on the basis of the local contrast of each pixel, where a Gaussian filter without approximation is used to avoid the duplication of pixel values that disturbs the strict pixel ordering. The main idea of the proposed method is that the problem of pixel ordering is divided into small subproblems which can be solved separately, and then the results are merged into one sequence of all ordered pixels. Moreover, the proposed method is extended from grayscale images to color ones in a consistent manner. Experimental results show that the state-of-the-art histogram specification method occasionally produces false patterns, which are alleviated by the proposed method. Those results demonstrate the effectiveness of the proposed method for exact histogram specification. |
| Document Type: | article in journal/newspaper |
| Language: | English |
| Relation: | https://www.mdpi.com/2313-433X/8/9/247; https://doaj.org/toc/2313-433X; https://doaj.org/article/ba2d3a00b0554cb6bccacce2a6a4c2b6 |
| DOI: | 10.3390/jimaging8090247 |
| Availability: | https://doi.org/10.3390/jimaging8090247 https://doaj.org/article/ba2d3a00b0554cb6bccacce2a6a4c2b6 |
| Accession Number: | edsbas.E2C62FCF |
| Database: | BASE |
Nájsť tento článok vo Web of Science | Abstract: | Histogram equalization is one of the basic image processing tasks for contrast enhancement, and its generalized version is histogram specification, which accepts arbitrary shapes of target histograms including uniform distributions for histogram equalization. It is well known that strictly ordered pixels in an image can be voted to any target histogram to achieve exact histogram specification. This paper proposes a method for ordering pixels in an image on the basis of the local contrast of each pixel, where a Gaussian filter without approximation is used to avoid the duplication of pixel values that disturbs the strict pixel ordering. The main idea of the proposed method is that the problem of pixel ordering is divided into small subproblems which can be solved separately, and then the results are merged into one sequence of all ordered pixels. Moreover, the proposed method is extended from grayscale images to color ones in a consistent manner. Experimental results show that the state-of-the-art histogram specification method occasionally produces false patterns, which are alleviated by the proposed method. Those results demonstrate the effectiveness of the proposed method for exact histogram specification. |
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| DOI: | 10.3390/jimaging8090247 |