Table 6 Peak signal-to-noise ratio value comparison between results obtained using different enhancement methods on three different standard benchmark face datasets
Database | LCS | HE | IIA | M_PSO | M_GA | BPDFHE | CLAHE | LLIE | Prop |
|---|---|---|---|---|---|---|---|---|---|
AR | |||||||||
 Image 1 | 23.135 | 17.921 | 23.135 | 14.430 | 15.239 | 27.1569 | 17.021 | 13.99 | 13.259 |
 Image 2 | 21.184 | 15.375 | 21.848 | 12.396 | 12.392 | 34.8048 | 16.348 | 14.281 | 12.6282 |
 Image 3 | 25.490 | 19.090 | 25.490 | 15.746 | 15.318 | 32.3678 | 18.724 | 13.833 | 12.437 |
 Image 4 | 24.003 | 14.126 | 24.003 | 12.846 | 12.428 | 40.5588 | 16.8669 | 17.726 | 8.8844 |
 Image 5 | 24.360 | 15.6500 | 24.360 | 14.5273 | 14.4144 | 40.5269 | 17.5406 | 17.654 | 9.147 |
 Image 6 | 24.2599 | 9.8793 | 24.259 | 14.1864 | 14.17 | 29.9462 | 17.1313 | 21.347 | 8.244 |
YF | |||||||||
 Image 1 | 27.071 | 12.472 | 27.071 | 14.101 | 13.269 | 34.115 | 23.451 | 26.014 | 8.069 |
 Image 2 | 36.541 | 12.581 | 36.541 | 13.711 | 13.757 | 35.481 | 20.531 | 15.104 | 8.197 |
 Image 3 | 37.271 | 17.085 | 37.271 | 13.207 | 6.607 | 37.806 | 21.755 | 23.831 | 9.759 |
 Image 4 | 42.581 | 13.731 | 42.581 | 14.659 | 14.048 | 25.339 | 19.812 | 14.259 | 8.837 |
 Image 5 | 39.031 | 18.110 | 39.030 | 2.2967 | 3.328 | 32.593 | 20.954 | 14.969 | 9.499 |
 Image 6 | 35.343 | 16.072 | 35.343 | 13.392 | 5.065 | 37.973 | 21.706 | 17.007 | 9.027 |
ORL | |||||||||
 Image 1 | 25.323 | 20.849 | 25.323 | 17.551 | 16.441 | 31.981 | 18.153 | 16.097 | 11.635 |
 Image 2 | 26.787 | 22.484 | 26.787 | 14.861 | 14.831 | 41.335 | 16.407 | 14.606 | 10.258 |
 Image 3 | 25.591 | 22.103 | 25.591 | 16.318 | 16.212 | 37.621 | 17.695 | 18.665 | 10.188 |
 Image 4 | 23.788 | 19.598 | 23.788 | 15.441 | 16.947 | 33.865 | 17.825 | 18.590 | 10.523 |
 Image 5 | 25.624 | 28.241 | 25.624 | 15.371 | 15.381 | 36.755 | 17.314 | 16.071 | 12.158 |
 Image 6 | 22.703 | 21.727 | 22.703 | 18.523 | 18.139 | 32.633 | 17.743 | 15.356 | 11.829 |