In[]:=
ManipulateGrid,{Text["RGB Color Codes"]},RowTextcolu=PixelValue,u[[1;;3]],Textcolv=PixelValue,v[[1;;3]],Spacer[10],{GraphicsRow[{Graphics[{If[colu!={0.,0.,0.},RGBColor[colu],White],RegularPolygon[4]},ImageSize200],Graphics[{If[colv!={0.,0.,0.},RGBColor[colv],White],RegularPolygon[4]},ImageSize200]},Spacings->200]},Alignment->Center,{{u,{590,620}},Locator},{{v,{590,440}},Locator}
Out[]=