shade plane with a color function color(x,y)

I am making a RGB color function which assigns an RGB color to each point in the plane. To check if it does what I think it should do (i.e. debugging it), it is helpful to be able to plot the function to see how the problematic areas are arising. How can I plot this function? i.e. is there something along the lines of

Plot[RGB[f[x,y],g[x,y],h[x,y]],{x,0,10},{y,0,10}]

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closely related: 50461 –  Kuba Jun 15 '14 at 8:38

cf = Function[{x, y}, ColorData["Rainbow"][Mean@{x, y}]];

Oh it just needs to be rescaled. ColorData domains are {0,1} –  mfvonh Jun 15 '14 at 3:03
RGBColor also takes values in the domain {0,1}. If you have your domain you can just divide by a constant to get the values in that range. –  mfvonh Jun 15 '14 at 3:21