* Only works for single-tiled images --> will error out cleanly, as currently
in other cases
* Save re-reading the codestream for the tile, and re-use code-blocks of the
previous decoding pass.
* Future improvements might involve improving opj_decompress, and the image writing logic,
to use this strategy.
However the intermediate buffer for decoding must still be smaller than 4
billion pixels, so this is useful for decoding at a lower resolution level,
or subtile decoding.
Instead of being the full tile size.
* Use a sparse array mechanism to store code-blocks and intermediate stages of
IDWT.
* IDWT, DC level shift and MCT stages are done just on that smaller array.
* Improve copy of tile component array to final image, by saving an intermediate
buffer.
* For full-tile decoding at reduced resolution, only allocate the tile buffer to
the reduced size, instead of the full-resolution size.
* Better document usage of opj_set_decode_area(), ie expecting coordinates
in full resolution/reference grid even if requesting at a lower resolution
factor
* Make sure that image->comps[].factor is set by opj_set_decode_area() and
opj_decode() from the value specified in opj_set_decoded_resolution_factor()
* opj_decompress: add 2 environmenet variables to test alternate ways of
using the API, namely USE_OPJ_SET_DECODED_RESOLUTION_FACTOR=YES to use
opj_set_decoded_resolution_factor() instead of parameters.cp_reduce, and
SKIP_OPJ_SET_DECODE_AREA=YES to not call opj_set_decode_area() if -d is
not specified.
PR #975 introduced a check that rejects images that have different bit depth/sign
per compoment in SIZ marker if the JP2 IHDR box has BPC != 255
This didn't work properly if decoding a .j2k file since the new bit added in
opj_cp_t wasn't initialized to the right value.
For clarity, tThis new bit has also been renamed to allow_different_bit_depth_sign
But looking closer at the code, it seems we were already tolerant to inconsistencies.
For example we parsed a JP2 BPCC box even if BPC != 255 (just a warning is emitted)
So failing hard in opj_j2k_read_siz() wouldn't be very inconsistent, and that
alone cannot protect against other issues, so just emit a warning if BPC != 255
and the SIZ marker contains different bit depth/sign per component.
Note: we could also check that the content of JP2 BPCC box is consistant with the one
of the SIZ marker.
Currently we allocate at least 8192 bytes for each codeblock, and copy
the relevant parts of the codestream in that per-codeblock buffer as we
decode packets.
As the whole codestream for the tile is ingested in memory and alive
during the decoding, we can directly point to it instead of copying. But
to do that, we need an intermediate concept, a 'chunk' of code-stream segment,
given that segments may be made of data at different places in the code-stream
when quality layers are used.
With that change, the decoding of MAPA_005.jp2 goes down from the previous
improvement of 2.7 GB down to 1.9 GB.
New profile:
n4: 1885648469 (heap allocation functions) malloc/new/new[], --alloc-fns, etc.
n1: 1610689344 0x4E78287: opj_aligned_malloc (opj_malloc.c:61)
n1: 1610689344 0x4E71D7B: opj_alloc_tile_component_data (tcd.c:676)
n1: 1610689344 0x4E7272C: opj_tcd_init_decode_tile (tcd.c:816)
n1: 1610689344 0x4E4BDD9: opj_j2k_read_tile_header (j2k.c:8618)
n1: 1610689344 0x4E4C8A2: opj_j2k_decode_tiles (j2k.c:10349)
n1: 1610689344 0x4E4E36E: opj_j2k_decode (j2k.c:7847)
n1: 1610689344 0x4E52FA2: opj_jp2_decode (jp2.c:1564)
n0: 1610689344 0x40374E: main (opj_decompress.c:1459)
n1: 219232541 0x4E4BBF0: opj_j2k_read_tile_header (j2k.c:4685)
n1: 219232541 0x4E4C8A2: opj_j2k_decode_tiles (j2k.c:10349)
n1: 219232541 0x4E4E36E: opj_j2k_decode (j2k.c:7847)
n1: 219232541 0x4E52FA2: opj_jp2_decode (jp2.c:1564)
n0: 219232541 0x40374E: main (opj_decompress.c:1459)
n1: 39822000 0x4E727A9: opj_tcd_init_decode_tile (tcd.c:1219)
n1: 39822000 0x4E4BDD9: opj_j2k_read_tile_header (j2k.c:8618)
n1: 39822000 0x4E4C8A2: opj_j2k_decode_tiles (j2k.c:10349)
n1: 39822000 0x4E4E36E: opj_j2k_decode (j2k.c:7847)
n1: 39822000 0x4E52FA2: opj_jp2_decode (jp2.c:1564)
n0: 39822000 0x40374E: main (opj_decompress.c:1459)
n0: 15904584 in 52 places, all below massif's threshold (1.00%)
Even Rouault
Even Rouault
Stefan Weil
Antonin Descampe