Convert PDF (CMYK) to CMYK image directly without loss of color

[SomenteRafael]

I'm tring convert a PDF (CMYK) to CMYK TIFF but seems like it is converted to RGB and back to CMYK. I'm using a PDF with an horizontal gradient from black to white and the result is a yellowish image. When I convert to PNG (RGB) instead of TIFF or JPG the image color is better, but it's still different, with less color nuance.

    public static void PDFTo(string input, string output)
    {
        var settings = new MagickReadSettings
        {
            Density = new Density(300, 300),
            ColorSpace = ColorSpace.CMYK
        };
        settings.ColorType = ColorType.ColorSeparation;
        using var images = new MagickImageCollection();
        images.Read(input, settings);

        var page = 1;
        foreach (var image in images)
        {
            image.ColorSpace = ColorSpace.CMYK;
            image.Format = MagickFormat.Tiff; // MagickFormat.jpg
            image.Write(output + input[input.LastIndexOf('\\')..^4] + "_" + page + ".tiff"); // ".jpg"
            page++;
        }
    }

How can I fix it? Is it possible? Is it a bug? Its viewers' bug and its all right with the images?

Input file	PDF
PNG result
JPG result
Colorfull input for tests	PDF

Maybe its not wrong, I don't know.

[dlemstra]

It took some time to figure out why this is happening. The problem here is that the PDF decoder of ImageMagick used an option called -dUseCIEColor that would give you this strange output. After some reading we found that we no longer need this option and that is why we removed it. This patch will become available in the next release and you will then get the following output:

I will try to publish that release this weekend.