Let me first add a link to your stackoverflow post: http://stackoverflow.com/questions/36714058/issues-converting-adobe-ai-and-psd-files-using-magick and include the code from there:
MagickReadSettings settings = new MagickReadSettings(); settings.Density = new Density(300); using (MagickImageCollection images = new MagickImageCollection()) { images.Read(file, settings); using (MagickImage horizontal = images.AppendHorizontally()) { file = path + "\\" + ThumbnailFolder + "\\TempThumb.Png"; horizontal.Write(path + "\\" + ThumbnailFolder + "\\TempThumb.Png"); } }