Ok lets use this picture as an example: Did they use 10 different pictures, each under the same exact lighting to create the same exact gradient, with the same exact dimensions, and then place them together in photoshop or something? (I believe this is unlikely) Or did they first take the picture in green (or any other color really) and then edit that specific color to make it in red, and then orange, and then yellow, etc. etc. (the same exact picture, copied 10 times, each copy with an altered color using a software) and then stitched those together? I'm thinking it's the latter. If so, what software would they use to do this? What first color would they choose to take the first picture with? (I'm thinking green, since green is used for green screens, and it's sort of the same principle) Thanks in advance!