After you process your HDR image you might notice a color cast when you compare it with the 0EV image. When I use Photomatix to process my HDR image set I can usually detect a warm/reddish color shift. No problem, you can use cooling filters or fiddle with the “hue” in the hue saturation adjustments or you can try Tim Grey’s method www.timgrey.com. He applies it to single shot images but there is no reason why it can’t be applied to HDR images.
Dup the layer (Ctrl-J) (Cmd-J)
Go Filter>Blur>Average (this is the average of all the pixels and is displayed as a solid color).
Go Image>Adjustments>Invert (this inverts or is the complimentary color)
Change blending mode to Color (reduce opacity, usually to about 25 and add color saturation back)
Below is an HDR image that has undergone the process and to see the before would not be very dramatic as the color shift is slight. The above steps reduced the blue cast to the image. To see how this technique can correct an extreme color cast I’ve shown a before and after of my daughter, Brooke (single shot). I left some of the warm tone by reducing the opacity to 20 because she likes the golden tan.