Brightening of items in inventory after default texture pack restored.

I changed my resource pack back to the default, and then everything just flashed and the whole screen was a lot lighter. I thought "Uhhhh, stupid monitor", but then checked out of minecraft and everything was normal. I then pressed f2 to take a screenshot to put here, and the background which was clear before behind the creative inventory darkened again (As it normally is). Please help. It just makes everything weird. I don't like it. I hope the picture explains it all. Also, after pressing f2, and the background darkening again strangely, it went back to being clear and hard to read the label for items.