The original color of the apple is bright red.
The picture intend to tell public what a red apple will look like from a patient with Cataract 白內障.
Most people think loss of vision is black but cataract patient see things a bit blur, yellow tone and nearly loss vision in the middle field.

影留存憶 - I hope public can remember this picture when they walk pass a poster with this "Red apple" in their mind. A totally black or extremely colorful pictures is not specific enough to give the message of "lossing vision".

攝出希望 -
A picture people remember could increase awareness of "lossing vision" and initiate more support to the sufferers