F1 mode dims the colors on a map displayed on the wall

When going into f1 mode the colors on a map hung in a frame gets dimmed. I was in creative when it happened. I hung the map onto the wall and then grabbed it using the pick block button, I went into f1 mode and that's when it happened. I tried to re-create the glitch into other worlds of mine, but it didn't seem to work. It might have been just that one world, I don't know... just a weird glitch I noticed...