The trick we are going to see today is very basic, but it has many possible implications. It depends on what you are really trying to do, however changing the background colour of an image can be very handy when we want to highlight a picture, or even sections of an image.
Let's see how it is done with just a line of CSS.
The image
The image we are going to highlight needs to have a transparent background. A gif could be what we need.The only thing we should consider when choosing the right image is that the transparent part of it will be the part changing colour. Thus, if we want to highlight only a specific part of it, we should make only that part transparent. For example, we could make a star sparkle when the mouse gets over it; or we could emulate a shining effect on a polished metal button.