Create snr-star.md

Author: Motohiro-TABUCHI

_pages/plugins/snr-star.md

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+---
+title: SNR* Tool
+categories: [plugins]
+---
+
+# SNR* Tool (Covariance-based SNR Estimation)
+
+An ImageJ macro for covariance-based SNR estimation.
+
+## Principle
+
+SNR* estimates signal variance using the covariance between two repeated images.
+
+![Principle](./snr_star_principle.jpg)
+
+Adapted from:  
+Tabuchi M, et al. JSRT, 2022.
+
+## Usage
+
+![Usage](./snr_star_usage.jpg)
+
+Step 1 Prepare the folder containing two observed images  
+Step 2 Draw an ROI on the first image  
+Step 3 SNR*, ROI size, signal variance, and noise variance will appear in the Log window
+
+## Video
+
+Demonstration of the SNR* tool:
+
+https://youtube.com/shorts/qBz2MlNHiCE
+
+## Download
+
+GitHub:  
+https://github.com/Motohiro-TABUCHI/SNR_star_Tool
+
+Zenodo (archived release):  
+https://zenodo.org/record/18666471
+
+## Reference
+
+Tabuchi M, Kiguchi T, Ikenaga H.  
+SNR estimation for image quality evaluation in X-ray CT.  
+Jpn J Radiol Technol. 2022;78:464–472. (in Japanese)