To be honest, I struggled with the depth of content that this lesson provided and how Photoshop was related to the initial activity (beads/weaving). That being said, I think I will try to emphasize CGI and even simpler data visualizations to focus the students on CS concepts. In the past I've used sketchfab.com as an extension in computer applications (when learning about image editors). I like the other poster's idea with the Gettysburg address, and might try something similar to it using stories in the news, presidential addresses or debates, etc.
For anyone looking for free programs for image creation/editing, I encourage you to check out GIMP and Inkscape, which are both free and powerful in their capabilities.