Dynamic Range is the difference in light levels in an image, between the darkest and the brightest areas. On an overcast day with little sun and few shadows, there will be a fairly low dynamic range, i.e. there will be no areas of deep black and no extreme bright spots. On a sunny day, however, in a scene with distinct shadows, there will be a greater difference between the brightest and darkest areas, and this is what we call a wide dynamic range or WDR (also known as High Dynamic Range, or HDR).