The discoloration in your skin is likely secondary to scar tissue and deposits (like hemosiderin) in the dermis itself. While LED light has been purported as a treatment for acne (with mixed results), it is likely not useful to lighten to treat scarring from acne.
You would probably need to look at peels or laser resurfacing to treat some of those areas of discoloration. If the areas are deep or dark enough or if your skin is dark it may be difficult to resolve these discolorations.
In addition, it is important to know that some of these marks can continue to fade over time on their own. Typically a good guideline is waiting about 6 months. There have also been anecdotal reports of topical scar medications like Mederma or ScarGuard being effective but it is possible these treatments may worsen your acne.
I hope this helps.
