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 "pixelated", 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 or ImageBox datasets of the DicomPrint object - e.g.:

printerObject.FilmBox.Attributes.Add(0x2010,0x0060,"CUBIC")
OR
printerObject.ImageBox.Attributes.Add(0x2010,0x0060,"CUBIC")

Alternative values are:

REPLICATE

Simply enlrage each pixel - giving a blocky appearance to enlarged pixels

BILINEAR

Simple interpolation

CUBIC

Conventional interpolation

NONE

Generally interpretted to mean 1:1 between input and output pixels