The tone curve is a powerful tool for adjusting an image. While HDR can bring out detail in every area of an image the tone curve can be used to bring out selective elements of a picture. The tone curve can also be used to spread out the tonal detail over a wider range of levels. The example below shows how this effect can bring alive a picture and make it more defined. A by-product of an "S" shaped curve is an increase in colour saturation. This is because the differences between the colour channels are increased by the curve.