# Feedback for a new(?) puzzle format

My wife likes solving puzzles and I like creating them. But I'm afraid my latest idea might not be as great as I thought - could you please beta-test it and give feedback on what to improve and how? Or has this idea been used by others I could learn from? The puzzle would be the image below, without any content or clue (at least initially).

Plotting the brightness of three horizontal slices of the image shows the following:

Mathematica code:
ListLinePlot[#,AspectRatio->1/4]&/@ImageData[img][[125;;375;;125,;;,1]]

It takes a little interpretation, but I think it says something like: