If you use Photoshop to create or edit an image then it will contain embedded information about the ‘Color Mode‘. To set up a dropdown attribute that displays and allows you to search for the ‘Color Mode‘, follow these steps:
Create a new attribute of type ‘dropdown‘ called ‘Color Mode‘. Click ‘Show on search‘ if you want to show the dropdown on the ‘advanced search‘ page.
Add attribute values with the following names and IPTC/EXIF Mapping fields:
RGB Color: 3
CMYK Color: 4
Create an ‘embedded data mapping‘ to map the embedded field XMP:Color Mode to your attribute.