How can we implement GrayScale in Aspose? XImage.SetData alternative also not found in Aspose.
You can convert PDF document from RGB colorspace to Grayscale as well use convert (only) image on particular page into grayscale using following code:
Aspose.Pdf.Document doc = new Aspose.Pdf.Document("input.pdf");
doc.Pages[1].MakeGrayscale();
doc.Save("output.pdf");