I know what you mean but usually if it isn't anything, it won't usually put colour there in my experience. I actually asked this myself on my thread because although I haven't been able to put colour where there isn't any by tweaking them, I wanted to know what others thought. They said the same thing too, so I wouldn't worry too much about that.
To add, I think where a photo is out of focus or pixelated, this can sometimes make the whole strip look colourful, but with a good clear photo it shouldn't if there isn't colour there