Clipping is a reference to a tone reaching a maximum value, i.e. pure black, pure white or some other colour. You have probably heard general statements that clipping is “bad” and you should avoid this, especially in the highlights. You can tell if a tone has clipped by viewing the histogram created by your camera. Here is an example of a histogram showing the highlights and shadows being clipped:
At first glance it appears that this is a “bad” exposure since the right side of the histogram has reached the maximum for all colours, especially for the blue channel. You might think that this is an overexposed image. However, you will also notice that the shadows have also clipped for all channels. When you view this histogram in your camera you won’t see the separate channels as illustrated here. This is taken from the histogram shown in Photoshop. What you will see in your camera may suggest that you should decrease your exposure. The clipped highlights will “flash” in the preview. However, this is a very good exposure for this subject. Before you make a decision about whether there should be clipping or not, you need to consider the subject that you are photographing. Let’s take a look at the image for this histogram:
The reason that this image has clipping in the highlights is that the reflection on the hood is a “specular” highlight, which is usually reproduced as pure white or another pure colour. A specular highlight is a reflection of the light source and is most evident on shiny objects. Also, the tires have some pure black in the image, which is very normal so the shadow shows a very small amount of clipping.
Here is the same image with the clipped highlights shown in red and the clipped shadows shown in purple. This is what you will see when you view the RAW image in the Camera RAW converter in Photoshop. In order to show the full tonal range of this particular image, you need to have some clipping in the shadows and the large specular highlight on the fender needs to be clipped.
Clipping is also indicated when only one or two channels reach their maximum or minimum. It is not necessary to have a pure white or pure black to show clipping. In the car example, a lot of the highlight clipping is shown where the blue channel has reached the maximum and the red and green have not. If I reduced the camera exposure so the highlights were not clipped, the image would be grossly underexposed.
Let’s look at another example of desirable clipping. In this image, the neon sign has a pure yellow colour and the sky is black since it was taken at nighttime. The highlights would be flashing in your camera preview since the yellow (maximum red and maximum green) is very bright and totally saturated.
Here is the same image as shown in the Camera RAW converter with the shadow clipping shown in purple and the highlight clipping shown in red. For the yellow part of the neon sign the red and green channel are at their maximum and the blue is at the minimum value. If you reduced your camera exposure to prevent highlight clipping, the image would be way too dark!
In summary, clipping can be good and is necessary for many images. The important thing to consider is what is being clipped and by how much. To say that there should never be any clipping is to say that we should never have a pure black, pure white or any other pure colour. Many images need a full tonal range from pure black to pure white. There are many times that I purposely clip the shadows, even a small amount, in order to create some black. The analogy I use is with music and bass tones. If you turn off the bass on your stereo, the music sounds “flat”. If you eliminate all blacks, your image will appear “flat”. The same holds true with highlights. You need to know how to mix this “recipe” in your images.
You also need to consider that the histogram in your camera is based on the JPEG preview and if you use the RAW format, the dynamic range is much greater than what is indicated.
The general rule of thumb is to use the maximum exposure that you can without clipping areas that should not be clipped. For example, a bride’s dress may show some minor clipping along the creases and folds if the dress is a satin or highly reflective cloth. However, the large area of the dress should not be clipped.
You also need to make sure that you have the right white balance. If your white balance is way off, there will be more clipping for some colours. For example, if your white balance is too low, everything will appear too blue and some light cool coloured objects will show clipping. With the right white balance, the clipping may disappear or be reduced!
I will be covering this and other important tips in my class at Niagara School of Imaging. I’ll show you more ways to improve your camera and Photoshop techniques for better quality and faster workflow. Bring your camera and energy!
Cheers,
Brian Lee
Digital Workflow and Production Essentials
