Modifying Pantone colors within an existing PDF document.

Q: I need to get the Pantone Color from a PDF and Change the Pantone
color with the New Value in the Same PDF. Could you please confirm me,
whether I can use PDFNet SDK for this purpose?
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A: PDFNet SDK (http://www.pdftron.com/net) can be used to edit
existing PDF documents (among other things). In particular, you can
obtain get the Pantone Color (associated with a DeviceN color or
Separation color space) from a PDF, modify the colorant value, and
then save the PDF.

As a starting point you may want to take a look at ElementReaderAdv
(http://www.pdftron.com/net/samplecode.html#ElementReaderAdv).

Element's color space and colorants can be accessed from its color
space (i.e. element.GetGState()). For example:

GState gs = element.GetGState();
ColorSpace cs = element.GetFillColorSpace()
if (cs.GetType() == ColorSpace.Type.e_separation) {
    Obj sep_cs = cs.GetSDFObj();
    string colorant_name = sep_cs.GetAt(1).GetName();
    ... Modify the colorant name ?
    sep_cs.InsertName(1, "LogoGreen");
    sep_cs.EraseAt(2);
}

This type of editing will work only when you are modifying the
separation color space itself. If you need to modify colorant values
in the page content stream, you would need to use the approach
illustrated in ElementEdit sample project (http://www.pdftron.com/net/
samplecode.html#ElementEdit). In this sample the program strips all
images from the page and changes text color to blue.