Add capability to decode only a subset of all components of an image.

This adds a opj_set_decoded_components(opj_codec_t *p_codec,
OPJ_UINT32 numcomps, const OPJ_UINT32* comps_indices) function,
and equivalent "opj_decompress -c compno[,compno]*" option.

When specified, neither the MCT transform nor JP2 channel transformations
will be applied.

Tests added for various combinations of whole image vs tiled-based decoding,
full or reduced resolution, use of decode area or not.

1 files changed, 21 insertions, 0 deletions

diff --git a/src/lib/openjp2/jp2.h b/src/lib/openjp2/jp2.h
index 3ff66ebe..34abd511 100644
--- a/src/lib/openjp2/jp2.h
+++ b/src/lib/openjp2/jp2.h
@@ -235,6 +235,12 @@ Decoding parameters are returned in jp2->j2k->cp.
 */
 void opj_jp2_setup_decoder(opj_jp2_t *jp2, opj_dparameters_t *parameters);
 
+/** Allocates worker threads for the compressor/decompressor.
+ *
+ * @param jp2 JP2 decompressor handle
+ * @param num_threads Number of threads.
+ * @return OPJ_TRUE in case of success.
+ */
 OPJ_BOOL opj_jp2_set_threads(opj_jp2_t *jp2, OPJ_UINT32 num_threads);
 
 /**
@@ -327,6 +333,21 @@ OPJ_BOOL opj_jp2_read_header(opj_stream_private_t *p_stream,
                              opj_image_t ** p_image,
                              opj_event_mgr_t * p_manager);
 
+/** Sets the indices of the components to decode.
+ *
+ * @param jp2 JP2 decompressor handle
+ * @param numcomps Number of components to decode.
+ * @param comps_indices Array of num_compts indices (numbering starting at 0)
+ *                     corresponding to the components to decode.
+ * @param p_manager Event manager;
+ *
+ * @return OPJ_TRUE in case of success.
+ */
+OPJ_BOOL opj_jp2_set_decoded_components(opj_jp2_t *jp2,
+                                        OPJ_UINT32 numcomps,
+                                        const OPJ_UINT32* comps_indices,
+                                        opj_event_mgr_t * p_manager);
+
 /**
  * Reads a tile header.
  * @param  p_jp2         the jpeg2000 codec.