Dynamic range (DR) is the measurable difference between light and dark extremes (white, black, highlights, and shadows) of composition values. Natural light determines our everyday “real-world” dynamic range of values and colors we see.
Devices such as plasma displays require near complete darkness to realize their full range. Print images viewed under inadequate ambient light may not be representative of their full dynamic range.
No absolutely pure color, white, or black exists in the real world. However, degrees of color, white, and black do, and may be measured. Photographers gauge the luminance range (brightness/darkness) of their compositions according to the allowable minimum and maximum dynamic range their camera can capture, the quality of the printed images, and/or the clarity of developed film images.
Black Clipping and White Clipping
Clipping refers to the loss of highlights or shadows detail under/overexposure during the image taking.
White clipping, called "blown highlights," refers to overexposed bright areas. This is due to overexposure or the camera’s sensor sensitivity. The clipped area will typically appear completely white or as a distorted color (too much red in grass or yellow in sky). Camera pixels saturated with light block out detail of that area, thus creating blown highlights.
In the same manner, when there is not enough light hitting the pixel (creating underexposed areas), detail is lost and only solid black is captured. Post processing (Photoshop tweaking) cannot bring detail back since no detail has been captured.
Dynamic Range in Cameras
When taking a picture, you should consider the dynamic range of the camera’s imaging sensor as well as the dynamic range of the scene to be shot. It is the job of the photographer to successfully capture the scene within the limitations of the camera’s dynamic range. And all cameras do not have the same dynamic range.
The camera’s dynamic range, measured in “stops,” describes the range of highest measurable light intensity (brightest highlights) to the lowest measurable light intensity (darkest shadows). The camera’s sensor reads the dynamic range according to the camera’s sophistication and capability. The result is evidenced in the quality of the output image.
A quality SLR (single lens reflex) camera has a better image sensor to produce better contrast ratio. That is, wider dynamic range. Camera shows what it captured on a histogram. By reading histogram, you will know if you have any white or black clipping.
A histogram is a visual representation of data frequency. Photography histograms are used to represent color distributions (pixels) and are helpful in understanding digital images.
In a stacked histogram, pixels may be sorted and stacked and intensity may be determined by the height of each stack. Pixels may also be sorted according to brightness; pure black is indicated as zero and pure white is “255”.
Histograms of correctly exposed images typically show shadow areas beginning at “0” (black or darkest color) that gradually increase and showing subtle highlight details. A smooth downward curve ending in “255” shows a correctly exposed image.
Histograms of underexposed images typically show many pixels with, or clustered at, “0” value and few in the highlight area. This indicates clipped shadows.
Histograms of overexposed images show many pixels with, or clustered at, value “255”.This indicates clipped highlights. Subtle highlight details are lost and few pixels fall within the shadow area.
Histograms with all of the pixels clustered in the mid-range values show lack of contrast, which typically results in a blurred or hazy image. Histograms that appear “combed” (vertically streaked) indicate some tones missing. For example, tones/values are redistributed over a wider tonal range when an image with low contrast has its levels and curves adjusted to improve its contrast.
High-dynamic-range (HDR) imaging produces a greater dynamic range of brightness than standard digital imaging. Different exposures of the same subject are combined to create a broader tonal range.
Non-HDR cameras (LDR and SLR) lose light and dark details. This may be resolved by taking multiple photographs at different exposure levels and combining them to produce a photograph representative of a broader tonal range.
Image Source: Ralph Nordstorm Photography