Because "clipping" - the cutting off of tonality at the left or right side of the histogram in digital photography - can cause you problems, it is worth paying attention to. But to arbitrarily define how a histogram should look or act is asking for trouble. If you look at a histogram and look at clipping without looking at the photo will lead you astray. The histogram is a guide, not a “speed limit” sort of thing that will get you arrested by the histogram police should you ignore it.
Let’s look at what is going on. All clipping tells you is that the scene’s pure white and pure black start beyond the limits of what you are seeing in the image. There are many situations where you will photograph and the histogram will clip automatically because the contrast range of the scene is beyond the capabilities of the camera. That means that no matter what you do, even if you adjust the histogram in the computer to “no longer” clip, you cannot recover detail that was never captured, which is what the clipped histogram will show.
But that might not matter. We don’t need to see every detail in a scene in order for a photograph to be successful. In fact, many times, we do not want to see every detail. If we were to look at the great photographer, W. Eugene Smith, and his work (he is considered by many to be the father of modern photojournalism), we would quickly discover that most of his images were “clipped” compared to the original scene or the negative. He went for a very dark sort of image in order to better communicate his vision to the viewer.
Black tones and dark areas are very subjective. We generally want to have at least something pure black, meaning those tones are just starting to clip. But some images, especially when processed with the tonal information RAW has, look better with the dark areas having no tones, just pure black, meaning the clipping is higher. On the other hand, whites tend to be very sensitive to clipping. Often we want the white tones to just barely hit the end of the histogram, just under clipping. But sometimes we have scenes that have very bright light or reflections that distract from our subject - in that case, we can let them go pure white, making more of the image "clip", but keeping our important detail.
The important thing is not whether we clip or not clip, but what happens when clipping occurs. Is this good for the photo or bad for the photo? Does the picture look better or worse? Will it print or reproduce properly?
Note: Outdoor Photographer columnist Rob Sheppard teaches many online photo workshops, such as The Magic of F-stops: Choosing the Right Aperture and Successful Publication Photography. In addition, BetterPhoto.com's digital photography school has a number of courses designed to show you how to get a good exposure with a digital camera.
Great stuff!!
Posted by: image restoration | October 25, 2009 at 10:48 PM