Fig 1.
1-level 2D-DWT (A–C) and 3-level 2D-DWT (D).
Table 1.
Effects of SS-DWT on lossless JPEG 2000 bitrates for step-skip decisions selected by the BH and a couple of its variants.
Table 2.
Results for SS-DWT, RDLS-DWT, RDLS-SS-DWT, and comparison with JPEG-LS and HEVC (lossless mode).
Fig 2.
SS-DWT step-skip decisions selected by BH(2) for Photo (left-hand panel), No-photo (a) (middle), and No-photo (b) (right-hand) images. Plotted are averages for subbands and transform levels, denoted subband:level (e.g., the bar labeled LH:2 presents distribution of step-skip decisions applied when computing LH subband at level 2 of SS-DWT).
Table 3.
Effects of SS-DWT on lossless JPEG 2000 bitrates for BH, RH, fixed SS-DWT variants, and for choosing among fixed transform variants.
Table 4.
Execution times of unmodified JPEG 2000 elements and of entropy calculation.
Fig 3.
SS-DWT bitrate changes for individual images.
rDWT−lossless JPEG 2000 bitrate for 3-level unmodified DWT (bpp); Δrvariant−SS-DWT bitrate change obtained with use of SS-DWT variants: RH(1) (A) and FIX1 (B).
Fig 4.
Entropy estimation-based and actual JPEG 2000 bitrate-based SS-DWT average bitrate changes (Δr) plotted against compression time relative to unmodified JPEG 2000 (Time rel.).
NO_DWT and variants over 5 times slower than JPEG 2000 are not plotted.
Table 5.
Effects of SS-DWT on lossless JPEG 2000 bitrates for entropy estimation-based BH, RH, and choosing among fixed transform variants.
Fig 5.
Entropy estimation-based SS-DWT bitrate changes for individual images.
rDWT−lossless JPEG 2000 bitrate for 3-level unmodified DWT (bpp); ΔrH0 variant−SS-DWT bitrate change obtained with the use of the entropy estimation-based variants: RH(1) (A) and choosing between FIX1, FIX2, and DWT (B).
Table 6.
Variability of bitrate improvements of Photo, No-photo (a) and No-photo (b) images for SS-DWT variants presented in Figs 3 and 5.