My high school math student had to solve this puzzle for his homework. I made it harder by not telling you what is the definition of $\mathbb{F}_7$. Neither why letter Q is used and which of his chapter this is.
Your aim is to reconstitute the original image and discover the pattern. Would you use your technique for any random picture and $\mathbb F_{17}$?
Note: the LaTeX mathbb font and color (blue) are different from the ones in puzzling.se, but that's not part of the puzzle (it was a URL link in the image).
Note bis: while it could be easier to solve it thanks to computers, I will favor no computers solutions and math computations. That's why no-computers
tag for this puzzle.
no-computers
tag :) $\endgroup$