I'm a graphic facilitator, using visuals to help groups be better at what they do. I create these large images, live. The original posters are 7 feet wide - and I need to edit them into smaller files for web and print. By popular request, here's how I edit the graphic recording posters afterwards.
You'll need photoshop, a digital camera that ideally takes raw files, and natural light. After the images are edited, the final step: I use photoshop to add a title, the session information, and my contact information to the bottom of the images.
Hope this helps! The best place for more resources is to search the Graphic Facilitation Facebook group (search in the top right) for previous threads. People compare cameras, setups, and other tips.