+ * \brief Parse pixel data from disk of [multi-]fragment RLE encoding.
+ * Compute the RLE extra information and store it in \ref RLEInfo
+ * for later pixel retrieval usage.
+ */
+void File::ComputeRLEInfo()
+{
+ std::string ts = GetTransferSyntax();
+ if ( !Global::GetTS()->IsRLELossless(ts) )
+ {
+ return;
+ }
+
+ // Encoded pixel data: for the time being we are only concerned with
+ // Jpeg or RLE Pixel data encodings.
+ // As stated in PS 3.5-2003, section 8.2 p44:
+ // "If sent in Encapsulated Format (i.e. other than the Native Format) the
+ // value representation OB is used".
+ // Hence we expect an OB value representation. Concerning OB VR,
+ // the section PS 3.5-2003, section A.4.c p 58-59, states:
+ // "For the Value Representations OB and OW, the encoding shall meet the
+ // following specifications depending on the Data element tag:"
+ // [...snip...]
+ // - the first item in the sequence of items before the encoded pixel
+ // data stream shall be basic offset table item. The basic offset table
+ // item value, however, is not required to be present"
+ ReadAndSkipEncapsulatedBasicOffsetTable();
+
+ // Encapsulated RLE Compressed Images (see PS 3.5-2003, Annex G)
+ // Loop on the individual frame[s] and store the information
+ // on the RLE fragments in a RLEFramesInfo.
+ // Note: - when only a single frame is present, this is a
+ // classical image.
+ // - when more than one frame are present, then we are in
+ // the case of a multi-frame image.
+ long frameLength;
+ while ( (frameLength = ReadTagLength(0xfffe, 0xe000)) != 0 )
+ {
+ // Parse the RLE Header and store the corresponding RLE Segment
+ // Offset Table information on fragments of this current Frame.
+ // Note that the fragment pixels themselves are not loaded
+ // (but just skipped).
+ long frameOffset = Fp->tellg();
+
+ uint32_t nbRleSegments = ReadInt32();
+ if ( nbRleSegments > 16 )
+ {
+ // There should be at most 15 segments (refer to RLEFrame class)
+ gdcmWarningMacro( "Too many segments.");
+ }
+
+ uint32_t rleSegmentOffsetTable[16];
+ for( int k = 1; k <= 15; k++ )
+ {
+ rleSegmentOffsetTable[k] = ReadInt32();
+ }
+
+ // Deduce from both RLE Header and frameLength
+ // the fragment length, and again store this info
+ // in a RLEFramesInfo.
+ long rleSegmentLength[15];
+ // skipping (not reading) RLE Segments
+ if ( nbRleSegments > 1)
+ {
+ for(unsigned int k = 1; k <= nbRleSegments-1; k++)
+ {
+ rleSegmentLength[k] = rleSegmentOffsetTable[k+1]
+ - rleSegmentOffsetTable[k];
+ SkipBytes(rleSegmentLength[k]);
+ }
+ }
+
+ rleSegmentLength[nbRleSegments] = frameLength
+ - rleSegmentOffsetTable[nbRleSegments];
+ SkipBytes(rleSegmentLength[nbRleSegments]);
+
+ // Store the collected info
+ RLEFrame *newFrame = new RLEFrame;
+ newFrame->SetNumberOfFragments(nbRleSegments);
+ for( unsigned int uk = 1; uk <= nbRleSegments; uk++ )
+ {
+ newFrame->SetOffset(uk,frameOffset + rleSegmentOffsetTable[uk]);
+ newFrame->SetLength(uk,rleSegmentLength[uk]);
+ }
+ RLEInfo->AddFrame(newFrame);
+ }
+
+ // Make sure that we encounter a 'Sequence Delimiter Item'
+ // at the end of the item :
+ if ( !ReadTag(0xfffe, 0xe0dd) )
+ {
+ gdcmWarningMacro( "No sequence delimiter item at end of RLE item sequence");
+ }
+}
+
+/**
+ * \brief Parse pixel data from disk of [multi-]fragment Jpeg encoding.
+ * Compute the jpeg extra information (fragment[s] offset[s] and
+ * length) and store it[them] in \ref JPEGInfo for later pixel
+ * retrieval usage.