Take a look at the photo above captured with my camera phone. I choose my camera phone because it does not do the best photos when compared with my DSLRs. That being said you can see the difference between the two images. First is the original and the second is the image processed in LAB color in GIMP.
All I did to fix the image was one unsharp mask on the L channel and two curves adjustment in the A and B channel. You really do not need to understand how LAB works to get some decent photos. I think the LAB corrected version restores the vibrancy back to the paint colours.
A little later I will be organizing a GIMP workflow to show you how you can vastly improve your camera phone images with very little work or real understanding of how LAB colour works.