opj_codec_t *p_codec,
opj_image_t **p_image);
+
+/** Restrict the number of components to decode.
+ *
+ * This function should be called after opj_read_header().
+ *
+ * This function enables to restrict the set of decoded components to the
+ * specified indices.
+ * Note that the current implementation (apply_color_transforms == OPJ_FALSE)
+ * is such that neither the multi-component transform at codestream level,
+ * nor JP2 channel transformations will be applied.
+ * Consequently the indices are relative to the codestream.
+ *
+ * Note: opj_decode_tile_data() should not be used together with opj_set_decoded_components().
+ *
+ * @param p_codec the jpeg2000 codec to read.
+ * @param numcomps Size of the comps_indices array.
+ * @param comps_indices Array of numcomps values representing the indices
+ * of the components to decode (relative to the
+ * codestream, starting at 0)
+ * @param apply_color_transforms Whether multi-component transform at codestream level
+ * or JP2 channel transformations should be applied.
+ * Currently this parameter should be set to OPJ_FALSE.
+ * Setting it to OPJ_TRUE will result in an error.
+ *
+ * @return OPJ_TRUE in case of success.
+ */
+OPJ_API OPJ_BOOL OPJ_CALLCONV opj_set_decoded_components(opj_codec_t *p_codec,
+ OPJ_UINT32 numcomps,
+ const OPJ_UINT32* comps_indices,
+ OPJ_BOOL apply_color_transforms);
+
/**
* Sets the given area to be decoded. This function should be called right after opj_read_header and before any tile header reading.
*
* that is to say at the highest resolution level, even if requesting the image at lower
* resolution levels.
*
+ * Generally opj_set_decode_area() should be followed by opj_decode(), and the
+ * codec cannot be re-used.
+ * In the particular case of an image made of a single tile, several sequences of
+ * calls to opoj_set_decode_area() and opj_decode() are allowed, and will bring
+ * performance improvements when reading an image by chunks.
+ *
* @param p_codec the jpeg2000 codec.
* @param p_image the decoded image previously setted by opj_read_header
* @param p_start_x the left position of the rectangle to decode (in image coordinates).
* Reads a tile data. This function is compulsory and allows one to decode tile data. opj_read_tile_header should be called before.
* The user may need to refer to the image got by opj_read_header to understand the size being taken by the tile.
*
+ * Note: opj_decode_tile_data() should not be used together with opj_set_decoded_components().
+ *
* @param p_codec the jpeg2000 codec.
* @param p_tile_index the index of the tile being decoded, this should be the value set by opj_read_tile_header.
* @param p_data pointer to a memory block that will hold the decoded data.