How to make a photo Sepia in Photoshop: Change the Image Mode of a B&W to RGB Color. Go to image-Adjust-Hue/Saturation. Check the colorize box, move the Hue slider to about 40, the saturation to 25, and the Lightness in the middle, or to your liking. You could use this adjustment to completely desaturate your color image, then set as above. As is everything else in PS, there are 25 plus ways to do anything.