Always capitalize and use trademarks in their correct form.
CORRECT: The image was enhanced with Adobe® Photoshop® Elements software.
INCORRECT: The image was photoshopped.
INCORRECT: The image was Photoshopped.
INCORRECT: The image was Adobe® Photoshopped.
Somebody hand me an aspirin — I’m crying in my coke here, because lawyers simply aren’t real people. I recognize that the company has an obligation to protect its trademark so people don’t xerox it so much its value lands in the dumpster — but this prescriptive grammar twaddle (look that up in webster’s) won’t exactly make photoshoppers quivver like Jell-O. The strategy is at best a legal band-aid.
Adobe’s website also uses, without the ® symbol, “whiteout,” “escalator,” “Frisbee“, “gramophone,” “linoleum,” “cellophane,” and “spam“. I think I’ve made my point, but if anyone would like to keep searching for additional evidence that Adobe doesn’t live in the same world it wants users of its products to live in, check out this Genercized Trademark list.