Fig. 1. Flowchart of proposed algorithm
Fig. 2. Illumination estimation results of intrinsic protrusion layer. (a) Intrinsic protrusion layer; (b) GKF; (c) BKF; (d) IBKF
Fig. 3. Reflection layer obtained by intrinsic protrusion layer. (a) Intrinsic protrusion layer; (b) GKF; (c) BKF; (d) IBKF
Fig. 4. Bilateral Gamma curves
Fig. 5. Illumination compensation layer and brightness transition layer obtained by different φ values.
Fig. 6. Gray histograms corresponding to different brightness transition layers and illumination compensation layer. (a) Illumination compensation layer; (b) φ=0.3; (c) φ=0.5; (d) φ=0.8
Fig. 7. Comparison of convergence curves before and after sparrow search improvement. (a) Before disturbance; (b) after disturbance
Fig. 8. Illumination compensation of reflection layer. (a) Brightness transition layer; (b) illumination layer; (c) reflection layer; (d) illumination compensation result
Fig. 9. Comparison of results before and after illumination compensation. (a) Original image; (b) RES1; (c) RES2; (d) proposed algorithm
Fig. 10. Comparison of results before and after adaptation. (a) RES3; (b) RES4; (c) RES5; (d) proposed algorithm
Fig. 11. Low illumination image enhancement results under natural light source obtained by different algorithms. (a) Original images; (b) SSR; (c) MSR; (d) MSRCR; (e) method in Ref. [
11]; (f) method in Ref. [
12];(g) method in Ref. [
13]; (h) proposed algorithm
Fig. 12. Low illumination image enhancement results under artificial light source obtained by different algorithms. (a) Original images; (b) SSR; (c) MSR; (d) MSRCR; (e) method in Ref. [
11]; (f) method in Ref. [
12]; (g) method in Ref. [
13]; (h) proposed algorithm
Evaluation indicator | Intrinsic protrusion layer | Reflection layer |
---|
GKF | BKF | IBKF |
---|
Average gradient | 10.2631 | 8.8822 | 10.6363 | 10.6792 |
|
Table 1. Quality assessment results of reflection layer
Evaluation indicator | Original image | RES1 | RES2 | RES3 | RES4 | RES5 | Proposed algorithm |
---|
SD | 61.2386 | 48.3111 | 58.6346 | 49.0672 | 53.7812 | 60.7832 | 64.2896 | AG | 10.0213 | 11.3349 | 11.4543 | 9.0229 | 10.0860 | 11.5988 | 12.3413 | IE | 7.1455 | 7.5191 | 7.5928 | 7.1910 | 7.4479 | 7.7171 | 7.8007 |
|
Table 2. Quality assessment of synthetic results
Scene | Evaluation indicator | Original image | SSR | MSR | MSRCR | Method in Ref.[11] | Method in Ref.[12] | Method in Ref.[13] | Proposed algorithm |
---|
Scene 1 | SD | 43.2219 | 38.4353 | 38.3464 | 41.9606 | 48.2158 | 46.9436 | 44.8264 | 47.7904 | AG | 3.7585 | 4.8005 | 4.7919 | 4.9422 | 4.6536 | 5.2797 | 4.6767 | 5.6144 | IE | 6.9867 | 6.7671 | 6.8003 | 7.1794 | 7.0427 | 7.3840 | 7.2749 | 7.4987 | Scene 2 | SD | 27.8077 | 35.5719 | 35.5086 | 36.4089 | 33.9395 | 43.1707 | 37.6329 | 46.1994 | AG | 3.7732 | 5.9386 | 5.9311 | 5.9930 | 5.0217 | 5.5853 | 4.9385 | 6.0015 | IE | 6.6220 | 6.7487 | 6.7789 | 6.9996 | 6.9573 | 7.3456 | 7.1473 | 7.4829 | Scene 3 | SD | 32.8273 | 35.4357 | 35.4087 | 37.0629 | 38.8858 | 47.3485 | 38.4523 | 46.9623 | AG | 5.2683 | 5.8262 | 5.8223 | 5.8015 | 6.4784 | 7.5816 | 6.0378 | 7.4200 | IE | 6.8849 | 7.0344 | 7.0451 | 7.1492 | 7.1463 | 7.5093 | 7.2500 | 7.5374 |
|
Table 3. Quality evaluation of low illumination image enhancement results under natural light source by different algorithms
Scene | Evaluation indicator | Original image | SSR | MSR | MSRCR | Method in Ref.[11] | Method in Ref.[12] | Method in Ref.[13] | Proposed algorithm |
---|
Scene 4 | SD | 43.8467 | 49.6197 | 49.2044 | 49.0843 | 50.8821 | 51.9138 | 47.9032 | 53.7664 | AG | 7.4814 | 9.2287 | 9.1622 | 9.0583 | 9.2054 | 9.8070 | 8.9136 | 9.9847 | IE | 6.9921 | 7.1340 | 7.2812 | 7.5212 | 7.2448 | 7.5872 | 7.4195 | 7.6999 | Scene 5 | SD | 26.8348 | 35.8094 | 35.8677 | 31.5348 | 30.2005 | 34.3291 | 31.1663 | 40.5358 | AG | 3.1687 | 4.5254 | 4.5247 | 4.5638 | 4.1127 | 4.4483 | 3.7470 | 5.2203 | IE | 6.2588 | 6.8977 | 6.9503 | 6.9610 | 6.4337 | 6.8370 | 6.8146 | 7.1465 | Scene 6 | SD | 57.3648 | 54.2550 | 54.1710 | 56.4558 | 58.4601 | 59.2007 | 55.0865 | 59.1924 | AG | 4.9223 | 6.1906 | 6.1845 | 6.2147 | 6.1405 | 6.4010 | 5.8252 | 6.2239 | IE | 7.2398 | 6.9972 | 7.0981 | 7.5846 | 7.4844 | 7.7346 | 7.6053 | 7.7727 |
|
Table 4. Quality evaluation of low illumination image enhancement results under artificial light source by different algorithms