Printers differ greatly in their default behaviour for smoothing/interpolating pixel data. DICOM does provide a mechanism for this to be controlled by the print SCU, but printers do vary in how they interpret and implement this functionality. If you find that a printout is showing the native resolution of the image (which users will think looks “pixilated”, as they often don’t understand how low resolution the original image really is!), then you can try adding attribute 2010,0060 to either the FilmBox (.NET version)/FilmBox (COM version) or ImageBox (.NET version)/ImageBox (COM version) datasets of the DicomPrint (.NET version)/DicomPrint (COM version) object.
DicomPrint printer = new DicomPrint(); // ... ... printer.FilmBox.Add(Keyword.MagnificationType, "CUBIC");
DicomPrint printer = new DicomPrint(); // ... ... printer.ImageBox.Add(Keyword.MagnificationType, "CUBIC");
Alternative values are: