First, use a photographic target with pure white, black, red, green, and blue on it. Put the target on the lower right or left corner of the image so it can be easily cropped out of the final image. Use photoshop or some other photo editing package to make adjustments to the image so that the photographic target comes into pure color as represented by the software’s RGB and greyscale refinement techniques. It’s not the best way to do it, but you can make smaller adjustments to images that are pretty close to correct.

Second, I’ve read on that one relatively continuous problem with digital cameras is there over-sensitivity to white balance due to the camera’s exposure/f-stop settings. The camera sometimes tweaks the image during processing to adjust for an underexposed image due to available light. Using your camera’s manual white balance setting could help, and it’s usually not hard to set. It’s always the last thing I change before shooting.