[FEATURE] CMYK Support

__Tasks:__

- [x] gather feedback for my changes
- [ ] merge #16  before this branch
- [ ] submit changes to the documentation


__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | yes
| Fixed tickets | none
| Doc           | none
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