Quoted from xTheBlackKnightx:LEDs in EMs wash out artwork, as they were not designed for this lighting.
The most common issue with LED implementation is exactly that... choosing the wrong brightness bulbs. Most people replace incandescents with LEDs that are 2-3x brighter which can definitely wash things out. The 1-LED or mini-SMD bulbs are the same brightness as incandescent, whereas everything else is much brighter.