You need to set it with SetArtifact:
using (MagickImage image = new MagickImage("6922044.jpg")) { image.SetArtifact("distort:viewport", "694x720-369+791"); image.Distort(DistortMethod.ScaleRotateTranslate, newdouble[] { 0, 0, 1, 1, 30 }); image.RePage(); image.Write("converted.jpg"); }