Q: I am developing an application which creates a pdf with a color
background. I am then placing a 1-bit TIF image on to the color
background. The issue I am running into is the print shop that I am
working with needs to have the TIF image in CMYK with all the color
information in the K value. The TIF shouldn't be split across the CMY
channels.
Here is the code I am using to insert the image.
var bmp = new Bitmap(page.CropFullFileName);
var image = Image.Create(doc, bmp);
var bld = new ElementBuilder();
var writer = new ElementWriter();
writer.Begin(pdfPage);
var element = bld.CreateImage(image, new Matrix2D(width, 0, 0, height,
0, 0));
GState gs = element.GetGState();
gs.SetFillColorSpace(ColorSpace.CreateDeviceCMYK());
writer.WritePlacedElement(element);
writer.End();
This results in an image that has values in all the channels. Is there
something that I need to do to only have the K value?
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A: The problem is that Bitmap GDI+ or .NET do not support CMYK TIFF
(they convert to RGB). Instead of passing .NET Bitmap to PDFNet you
can insert TIFF directly using pdftron.PDF.Image.Create("my.tiff") -
(see AddImage for sample code). This way PDFNet will process TIFF
directly and will be able to preserve CMYK information.