noticeably bright and showy; very vivid in color, especially so as to create an unpleasantly harsh or unnatural effect.
Merriam-Webster Online Dictionary
garish (adjective)1.
clothed in vivid colors
2.
a) excessively or disturbingly vivid - garish colors garish imagery
b) offensively or distressingly bright - glaring
3.
tastelessly showy - flashy gaudy