In[]:=
ManipulateGrid
Image[
]
,{Text["RGB Color Codes"]},RowTextcolu=PixelValue
Image[
]
,u[[1;;3]],Textcolv=PixelValue
Image[
]
,v[[1;;3]],Spacer[10],{GraphicsRow[{Graphics[{If[colu!={0.,0.,0.},RGBColor[colu],White],RegularPolygon[4]},ImageSize200],Graphics[{If[colv!={0.,0.,0.},RGBColor[colv],White],RegularPolygon[4]},ImageSize200]},Spacings->200]},Alignment->Center,{{u,{590,620}},Locator},{{v,{590,440}},Locator}
Out[]=
​
RGB Color Codes
{0.470588,0.470588,0.466667}
{0.470588,0.470588,0.466667}