Color is inverted in CMYK

Today I tesetd exporting a PSD that was in CMYK mode, and I got an x-ray like image.
So I tested example-cmyk.psd, and got similar result.

![example-cmyk-thumbnail](https://cloud.githubusercontent.com/assets/369170/3475031/9c2c2b7e-02eb-11e4-92ca-5937b0ee4ec5.png)

Below is export after converting PSD to RGB mode.

![example-rgb-thumbnail](https://cloud.githubusercontent.com/assets/369170/3475038/aa197d72-02eb-11e4-8138-3a0e2e65fcf8.png)

Is this a bug?

Environment: OS X 10.9, Ruby 2.0.0 (using rvm), gem version psd(3.2.2), psd_native(1.1.2)
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