Open your photo manipulation program. The easiest program to use for RGB to CYMK conversion is Adobe Photoshop.
If using another program, consult the software's user manual to find out if you need to install additional plug-ins for conversion purposes.
Open the image file in the photo manipulation program. Click on "File," then "Open," then select the image file and click the "Open" button.
If you have created an image from scratch, make sure to save the original file.
Select "Image" on the "File" menu through Adobe Photoshop. Select "Mode" on the drop-down menu, and navigate through the options until you see a selection for "CMYK Color." Select "CMYK Color" so that there is a check mark next to it.
Save the photo by opening the "File" drop-down menu and clicking "Save As" after you have converted the image from RGB to CYMK. Choose another name for the edited image so that can keep the original file. Example: A picture of a tree is saved as "Tree"; after you turn the picture of a flower to CYMK, save it as "CYMKTree."