Photoshop Chroma Key HOW-TO / Photoshop Green Screen HOW-TO. This is how to chroma key in Photoshop. At a high-level, it's simply taking a photo of a subject in front of a solid background and then "keying out" the background to replace with another background. This is easy to do within Photoshop and I demonstrate Photoshop green screening step-by-step within this video. Please share this video with others and be sure to check out my other videos on my channel too! Have a good day!