I convert image based on CMYK to image based on RGB in the following way using ImageMagick(command Line) :
convert.exe -profile icc:JapanColor2001Coate
You should first add the old profile and then the new profile:
using (MagickImage image = new MagickImage("input.jpg"))
{
// Tell ImageMagick what we're starting with
image.AddProfile(new ColorProfile(@"C:\Path\JapanColor2001Coated.icc"));
// Tell it to convert - the details are handled for you by the library
image.AddProfile(ColorProfile.SRGB);
// You're done. Save it.
image.Write("output.jpg");
}
Another example here: https://magick.codeplex.com/wikipage?title=Convert%20image
Notice in the linked example they're converting from a standard CMYK, which means you don't need to load a custom icc profile - the standard CMYK is already in Magick.net, as ColorProfile.USWebCoatedSWOP
.
If you need more help feel free to start a discussion here: https://magick.codeplex.com/discussions. If you post a message there please include a link to your source image.