PDF MRC is algorithm that optimizes PDF page content and makes PDF page size smaller. In most cases the PDF MRC compressor uses JBIG2 and JPEG2000 compression for image-resources because these are the best algorithms for black-white and color images.
If you need to open and write PDF MRC document, you need VintaSoft Imaging .NET SDK, VintaSoft PDF .NET Plug-in, VintaSoft JBIG2 .NET Plug-in and VintaSoft JPEG2000 .NET Plug-in.