I'm doing a space game. I've made a very nice background image with a bit of gas and some nice colourful stars. Since my game needs to scroll, I'm trying to work out the best way to add some parallax movement to that. When there are other objects on the screen, it's no problem because the movement against those objects give the illusion of movement, but when there are no other objects, everything appears static.
I assume people have some experience with this, so I'd appreciate any thoughts on how to achieve the illusion of movement. I've tried a scrolling image of stars ontop of my background, but it doesn't look very good and it ruins the background image a bit. Also, because some of the stars are online 1 pixel across, they seem to flicker badly when the movement is <1 pixel.
Another idea is to have some larger objects such as rocks which could continually fly past the screen, but I'm not sure how many would be needed to make it look nice.
Does anybody have any examples or ideas?