Get SpotColor Names

Is there a possibility to get the names of the spotcolors used in a pdf?
I'm using c#. Maybe there is a workaround with ghostscript?

color seperation

I searched the ghostscript doc but didn't find the thing.
Also tried with itextsharp.

Yes, you can extract the spot color names used in a PDF using Ghostscript. Here is an example of how to do it with C# and Ghostscript:

using System;
using System.Diagnostics;
using System.IO;

namespace GetSpotColorsFromPDF
{
    class Program
    {
        static void Main(string[] args)
        {
            var filePath = @"path\to\pdf";
            var outputFile = @"path\to\output.txt";

            var gsProcess = new Process
            {
                StartInfo = new ProcessStartInfo
                {
                    FileName = @"path\to\gswin64c.exe",
                    Arguments = $"-dNODISPLAY -dDumpSpotColors -sOutputFile={outputFile} {filePath}",
                    RedirectStandardOutput = true,
                    UseShellExecute = false,
                    CreateNoWindow = true,
                }
            };

            gsProcess.Start();
            gsProcess.WaitForExit();

            var output = File.ReadAllText(outputFile);
            Console.WriteLine(output);
        }
    }
}

Note that you need to have Ghostscript installed on your machine and specify the path to the gswin64c.exe executable in the code. The -dNODISPLAY and -dDumpSpotColors arguments are used to extract the spot color information from the PDF and the -sOutputFile argument is used to specify the output file for the extracted information. The extracted information will be saved to the specified output file and then read into a string and printed to the console.

The output of -dPDFINFO will be determined by the file contents so start with a valid empty file and using OP windows version 1000\gswin64c

gswin64c -dPDFINFO blank.pdf -o should look like this (note this is console copy

GPL Ghostscript 10.0.0 (2022-09-21)
Copyright (C) 2022 Artifex Software, Inc.  All rights reserved.
This software is supplied under the GNU AGPLv3 and comes with NO WARRANTY:
see the file COPYING for details.

        File has 1 page.

Producer: GPL Ghostscript 10.00.0
CreationDate: D:20230115003354Z00'00'
ModDate: D:20230115003354Z00'00'

Processing pages 1 through 1.
Page 1 MediaBox: [0 0 595 842]


C:\Apps\PDF\GS\gs1000w64\bin>

to suppress the copy write use -q

to save in a file use level2 redirection

gswin64c -q -dBATCH -dPDFINFO blank.pdf 2>out.txt

To filter output of text file use pipe filters

Does it have spot colours

What are they

>As long as no open standard for spot colours exists, TCPDF users will have to buy a colour book by one of the colour manufacturers and insert the values and names of spot colours directly

So here the names are on a RGB scale

- Dark Green   is 0,71,57
- Light Yellow is 255,246,142
- Black        is 39,36,37
- Red          is 166,40,52
- Green        is 0,132,75
- Blue         is 0,97,157
- Yellow       is 255,202,9

But black is not full black is there a better way? yes of course

type example_037.pdf|find /i "/separation" Now we can see the CMYK spots

In this simplified case the CMYK values after each name are shown as for example Full Black = [0.000000 0.000000 0.000000 1.000000].
Note often the separation may be encoded inside the PDF data thus you need to decompress the data first to do the search. There are several tools to do the decompression, so common cross platform ones are qpdf (FOSS) mutool (partner to GhostScript) and PDFtk amongst others.

cpdf -list-spot-colors in.pdf will list them, one per line, to standard output.