While picture quality can easily be improved by making colors more vivid, you don't want to go overboard with color saturation.
A picture's inherent color intensity or color saturation is often inadequate for online publishing. A current trend is to exaggerate an image's color saturation to levels that would otherwise look unnatural, but are well suited to computer monitors and mobile phone screens.
To change an image's color saturation, choose the command Adjust > Saturation.
The same picture at different levels of color saturation.