• P-ISSN 0974-6846 E-ISSN 0974-5645

Indian Journal of Science and Technology


Indian Journal of Science and Technology

Year: 2023, Volume: 16, Issue: 32, Pages: 2534-2539

Original Article

Enhancement of Proton Density Magnetic Resonance Images using Histogram Equalization and Unsharp Masking

Received Date:31 March 2023, Accepted Date:19 July 2023, Published Date:28 August 2023


Objective: The main objective of this study is to enhance the contrast and edge information present in the Proton density magnetic resonance medical images to increase the perception of information and provide better visualization format for effective diagnostics and treatment. Method: In the proposed algorithm, adaptive histogram equalization is applied to the input proton density magnetic resonance image to enhance the contrast followed by the unsharp mask filtering to improve the high frequency edge information of the image. Four proton density magnetic resonance images were downloaded from the dataset available in National Library of Medicine website, the experiment was carried out by writing the MATLAB code and executed by Intel Pentium Processor CPU4417U @ 2.3 GHz. Findings: Results reveal that the proposed method out performs adaptive histogram equalization (AHE) technique and Classical Unsharp Masking Filter (CUMF) both in terms of visual quality along with edge preservation and contrast enhancement. The quality of output image from the proposed method is enhanced by 1.34 times over AHE & 1.88 times over CUMF in terms of Spatial Frequency and 1.33 times over AHE & 2.18 times over CUMF in terms of Sharpness. Novelty: This study combines both histogram equalization and unsharp masking to enhance both contrast and edge information of proton density magnetic resonance medical images for effective diagnostics and treatment.

Keywords: Proton Density Magnetic Resonance Images; Medical Image Enhancement; Unsharp Mask Filter; Histogram Equalization; Spatial Frequency; Mean Gradient; Sharpness


  1. Gonzalez RC, Woods RE. Digital Image processing. Prentice Hall. 2018.
  2. Tanaka H, Taguchi A. GHE Mechanism for Preserving Mean Brightness of the Original Image. 2021 International Symposium on Intelligent Signal Processing and Communication Systems (ISPACS). 2021. Available from: https://doi.org/10.1109/ISPACS51563.2021.9651115
  3. Suharyanto, Hasibuan ZA, Andono PN, Pujiono D, Setiadi RIM. Contrast Limited Adaptive Histogram Equalization for Underwater Image Matching Optimization use SURF. Journal of Physics: Conference Series. 2021;1803(1):012008. Available from: https://doi.org/10.1088/1742-6596/1803/1/012008
  4. Shi Z, Chen Y, Gavves E, Mettes P, Snoek CGM. Unsharp Mask Guided Filtering. IEEE Transactions on Image Processing. 2021;30:7472–7485. Available from: https://doi.org/10.1109/TIP.2021.3106812
  5. Wang HWCXDBCYDCWMMH. Image Quality Based on Gradient, Visual Saliency and Color information. International Journal of Digital Multimedia Broadcasting. 2022. Available from: https:// doi.org/10.1155/2022/7540810
  6. Amelia CS. Entropy in Image Analysis. 2019. Available from: https://doi.org/10.3390/e21050502
  7. Liu Z, Hong H, Gan Z, Wang J, Chen Y. An Improved Method for Evaluating Image Sharpness Based on Edge Information. Applied Sciences. 2022;12(13):6712. Available from: https://doi.org/10.3390/app12136712


© 2023 Kannan & Perumal. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Published By Indian Society for Education and Environment (iSee)


Subscribe now for latest articles and news.