Why is it so hard to see black and blue?

The Salvation Army South Africa have used the dress that recently sparked a debate over it's colour.  They ask why is it so hard to see black and blue?  We must speak out against domestic abuse.  We must stop abuse against all victims. Physical violence only one form of domestic abuse - the other forms are psychological, sexual, financial and emotional. Victims can experience one or all of the types. 

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