Datacolor's SpyderCube 3D Cube for RAW Color Calibration is a compact (1.5"/3.8 cm square) - digital color balancing tool that not only allows you to correct the color temperature but also the exposure, brightness and black point of your images. The SpyderCube is a spectrally neutral three-dimensional tool that's small enough to fit in your pocket or camera bag and gives you all the features needed to easily adjust your images in post-production. Its multi-sided construction allows special attention to highlights and shadows and contains more features for image control than a gray card or white balance tool.
Just place the SpyderCube in the lighting conditions under which you will be photographing. Orient the cube so that the lower black face, containing the black trap, is at the bottom front and the two split white/gray faces are both visible. Take a photograph that includes the Cube. It makes several measurements that make it possible for you to be confident that your colors are accurate, your shadows and highlights are properly exposed and your image is adjusted to the ideal density, regardless of the lighting conditions.