All image quality metrics you need in one package.

image, quality, performance, metric, measure, ergas, q, psnr, pansharpening, image-processing, quality-metrics, super-resolution
pip install sewar==0.4.6


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Sewar is a python package for image quality assessment using different metrics. You can check documentation here.

Implemented metrics

  • Mean Squared Error (MSE)
  • Root Mean Squared Error (RMSE)
  • Peak Signal-to-Noise Ratio (PSNR) [1]
  • Structural Similarity Index (SSIM) [1]
  • Universal Quality Image Index (UQI) [2]
  • Multi-scale Structural Similarity Index (MS-SSIM) [3]
  • Erreur Relative Globale Adimensionnelle de Synthèse (ERGAS) [4]
  • Spatial Correlation Coefficient (SCC) [5]
  • Relative Average Spectral Error (RASE) [6]
  • Spectral Angle Mapper (SAM) [7]
  • Spectral Distortion Index (D_lambda) [8]
  • Spatial Distortion Index (D_S) [8]
  • Quality with No Reference (QNR) [8]
  • Visual Information Fidelity (VIF) [9]
  • Block Sensitive - Peak Signal-to-Noise Ratio (PSNR-B) [10]


  • Add command-line support for No-reference metrics


Just as simple as

pip install sewar

Example usage

a simple example to use UQI

>>> from sewar.full_ref import uqi
>>> uqi(img1,img2)

Example usage for command line interface

sewar [metric] [GT path] [P path] (any extra parameters)

An example to use SSIM

foo@bar:~$ sewar ssim images/ground_truth.tif images/deformed.tif -ws 13
ssim : 0.8947009811410856

Available metrics list

mse, rmse, psnr, rmse_sw, uqi, ssim, ergas, scc, rase, sam, msssim, vifp, psnrb 


Special thanks to @sachinpuranik99 and @sunwj.


[1] "Image quality assessment: from error visibility to structural similarity." 2004)
[2] "A universal image quality index." (2002)
[3] "Multiscale structural similarity for image quality assessment." (2003)
[4] "Quality of high resolution synthesised images: Is there a simple criterion?." (2000)
[5] "A wavelet transform method to merge Landsat TM and SPOT panchromatic data." (1998)
[6] "Fusion of multispectral and panchromatic images using improved IHS and PCA mergers based on wavelet decomposition." (2004)
[7] "Discrimination among semi-arid landscape endmembers using the spectral angle mapper (SAM) algorithm." (1992)
[8] "Multispectral and panchromatic data fusion assessment without reference." (2008)
[9] "Image information and visual quality." (2006)
[10] "Quality Assessment of Deblocked Images" (2011)