Warhol these pictures
Mathematica

namedColors = {Red, Green, Blue, Black, White, Gray, Cyan, Magenta, Yellow, Brown, Orange, Pink, Purple};
    myRules = 
      Table[Rule[namedColors[[i]], RandomChoice[namedColors]], {j, 4}, {i,
         Length[namedColors]}];

myImages = {--images here--};

Grid@Table[ColorQuantize[ColorReplace[myImages[[i]], myRules[[j]]],5], 
{i, Length[myImages]}, {j, 4}]