To fade in color — when the color of something (clothes, painting, scenery) becomes lighter or less vivid over time or due to light/rubbing.
長い間窓辺に置いておいたポスターの色褪めがひどい。
The poster left by the window for a long time has severely faded.
日焼けで服の色褪めが早まった。
Sun exposure sped up the fading of the clothes' color.
写真の鮮やかさが年を経て少し色褪めてきた。
The vividness of the photo has faded a bit over the years.
彼女の顔色が色褪めるほどの驚きだった。
It was such a shock that her complexion went pale.