Table 5. Effects of SS-DWT on lossless JPEG 2000 bitrates for entropy estimation-based BH, RH, and choosing among fixed transform variants.
| Transform variant | Complexity | Time | Images | ||||
|---|---|---|---|---|---|---|---|
| rel. | Photo | No-photo | No-photo(a) | No-photo(b) | All | ||
| r DWT | TD + TE + TR | 1.00 | 3.9975 | 2.9162 | 3.2882 | 2.7348 | 3.6395 |
| ΔrH0 BH(1) | 5.33 TD + 7.33 TH0 + TE + TR | 1.29 | -0.72% | -13.46% | -27.45% | -6.64% | -4.94% |
| ΔrH0 BH(2) | 9.67 TD + 12.67 TH0 + TE + TR | 1.56 | -0.75% | -13.50% | -27.79% | -6.53% | -4.97% |
| ΔrH0 RH(1) | 3.42 TD + 5.33 TH0 + TE + TR | 1.17 | -0.79% | -13.84% | -27.59% | -7.13% | -5.11% |
| ΔrH0 RH(2) | 5.83 TD + 8.67 TH0 + TE + TR | 1.33 | -0.79% | -13.65% | -27.62% | -6.83% | -5.05% |
| ΔrH0 NO_DWT, DWT | 1.00 TD + 2.00 TH0 + TE + TR | 1.02 | 0.00% | -5.43% | -17.35% | 0.38% | -1.80% |
| ΔrH0 FIX1, DWT | 1.22 TD + 1.75 TH0 + TE + TR | 1.03 | -0.44% | -11.13% | -22.07% | -5.79% | -3.98% |
| ΔrH0 FIX1, DWT, NO_DWT | 1.22 TD + 2.75 TH0 + TE + TR | 1.03 | -0.44% | -11.54% | -23.54% | -5.68% | -4.12% |
| ΔrH0 FIX2, DWT | 1.19 TD + 2.00 TH0 + TE + TR | 1.03 | -0.12% | -13.76% | -29.27% | -6.19% | -4.63% |
| ΔrH0 FIX2, DWT, NO_DWT | 1.19 TD + 3.00 TH0 + TE + TR | 1.03 | -0.12% | -13.39% | -28.46% | -6.03% | -4.51% |
| ΔrH0 FIX1, FIX2 | 0.50 TD + 1.67 TH0 + TE + TR | 0.99 | 0.03% | -13.99% | -29.04% | -6.64% | -4.61% |
| ΔrH0 FIX1, FIX2, DWT | 1.22 TD + 2.42 TH0 + TE + TR | 1.03 | -0.47% | -14.10% | -29.04% | -6.81% | -4.98% |
| ΔrH0 FIX1, FIX2, DWT, NO-DWT | 1.22 TD + 3.42 TH0 + TE + TR | 1.04 | -0.47% | -13.77% | -28.34% | -6.66% | -4.87% |
rDWT−average lossless JPEG 2000 bitrate for 3-level unmodified DWT (bpp); ΔrH0 variant_list−average bitrate change obtained for listed variants by employing entropy estimation for selecting fixed variants or steps to be skipped; Complexity–compression process computational time complexity including complexity of the heuristic or the variant selection; Time rel.–compression time relative to time of unmodified JPEG 2000.