Table 4. Class-wise comparison of recall for top 20 retrievals.

Class and Method	Visual words integration SIFT-SURF	Weighted average (0.7-0.3) SIFT-SURF	Color SIFT- EODH [37]	Spatial BoF [53]	SIFT-LBP [20]	HOG-LBP [20]
Africa	12.02 ± 0.39	10.68 ± 0.16	14.92	12.80	11.40	11.00
Beach	12.08 ± 0.28	11.34 ± 0.34	7.56	10.80	11.60	9.40
Buildings	13.93 ± 0.75	13.53 ± 0.31	10.78	10.60	8.60	11.20
Buses	18.73 ± 0.17	17.30 ± 0.30	19.34	18.80	18.60	18.20
Dinosaurs	19.98 ± 0.01	19.95 ± 0.03	19.80	19.60	19.60	18.80
Elephants	14.15 ± 0.38	13.52 ± 0.32	13.18	15.60	11.60	9.80
Flowers	17.67 ± 0.15	17.30 ± 0.13	18.24	14.20	16.60	17.00
Horses	16.55 ± 0.14	15.11 ± 0.19	17.38	18.60	13.60	10.40
Mountains	12.22 ± 0.14	11.78 ± 0.21	11.70	8.40	9.20	7.40
Food	13.02 ± 0.35	10.65 ± 0.32	12.44	10.00	10.60	11.00
Mean	15.03	14.12	14.53	13.94	13.14	12.42