diff options
| author | Even Rouault <even.rouault@spatialys.com> | 2017-08-21 12:25:38 +0200 |
|---|---|---|
| committer | Even Rouault <even.rouault@spatialys.com> | 2017-08-21 12:25:38 +0200 |
| commit | 17a7ac42d581c537cfc1da4324e53047ad82b13e (patch) | |
| tree | 5101231652db0c3117454e531a45db5e190e28fe /src | |
| parent | f87c5ef7ebef3d7a908e98f2de1b6a0336ae57ae (diff) | |
Add comments for filter_width values
Diffstat (limited to 'src')
| -rw-r--r-- | src/lib/openjp2/dwt.c | 5 | ||||
| -rw-r--r-- | src/lib/openjp2/tcd.c | 8 |
2 files changed, 13 insertions, 0 deletions
diff --git a/src/lib/openjp2/dwt.c b/src/lib/openjp2/dwt.c index 96d54df3..b8bbe20a 100644 --- a/src/lib/openjp2/dwt.c +++ b/src/lib/openjp2/dwt.c @@ -1676,6 +1676,8 @@ static OPJ_BOOL opj_dwt_decode_partial_tile(opj_tcd_t *tcd, opj_dwt_t h; opj_dwt_t v; OPJ_UINT32 resno; + /* This value matches the maximum left/right extension given in tables */ + /* F.2 and F.3 of the standard. */ const OPJ_UINT32 filter_width = 2U; opj_tcd_resolution_t* tr = tilec->resolutions; @@ -2255,6 +2257,9 @@ OPJ_BOOL opj_dwt_decode_partial_97(opj_tcd_t *tcd, opj_v4dwt_t h; opj_v4dwt_t v; OPJ_UINT32 resno; + /* This value matches the maximum left/right extension given in tables */ + /* F.2 and F.3 of the standard. Note: in opj_tcd_is_subband_area_of_interest() */ + /* we currently use 3. */ const OPJ_UINT32 filter_width = 4U; opj_tcd_resolution_t* tr = tilec->resolutions; diff --git a/src/lib/openjp2/tcd.c b/src/lib/openjp2/tcd.c index 5e4681c4..7a5e2b44 100644 --- a/src/lib/openjp2/tcd.c +++ b/src/lib/openjp2/tcd.c @@ -2381,6 +2381,14 @@ OPJ_BOOL opj_tcd_is_subband_area_of_interest(opj_tcd_t *tcd, OPJ_UINT32 band_x1, OPJ_UINT32 band_y1) { + /* Note: those values for filter_margin are in part the result of */ + /* experimentation. The value 2 for QMFBID=1 (5x3 filter) can be linked */ + /* to the maximum left/right extension given in tables F.2 and F.3 of the */ + /* standard. The value 3 for QMFBID=0 (9x7 filter) is more suspicious, */ + /* since F.2 and F.3 would lead to 4 instead, so the current 3 might be */ + /* needed to be bumped to 4, in case inconsistencies are found while */ + /* decoding parts of irreversible coded images. */ + /* See opj_dwt_decode_partial_53 and opj_dwt_decode_partial_97 as well */ OPJ_UINT32 filter_margin = (tcd->tcp->tccps[compno].qmfbid == 1) ? 2 : 3; opj_tcd_tilecomp_t *tilec = &(tcd->tcd_image->tiles->comps[compno]); opj_image_comp_t* image_comp = &(tcd->image->comps[compno]); |