Images with a CMYK color profile may be displaying colors as inverted after they are exported from Apple's Preview application and opened in third-party programs. According to a recently published Apple knowledge base article, CMYK JPEG colors can be distorted depending on the program opening the file.
To alleviate this problem, it is recommended users change the color profile of their images before exporting them from Preview or, if you would like to maintain the CMYK color profile, use the TIFF format.
To change your color profile, open your image in Preview.
Navigate to Tools > Match to profile...
From the Color Model window, choose RGB.
From the ColorSync Profile menu, choose Generic RGB Profile.
Click, OK and save the file as a JPEG.
A word of warning, you can expect color changes when adjusting the color profiles from CMYK to RGB. Be sure to compare the two if using them in production material.