Coping with Contrast
The optimum exposure for most images is when there is an even spread of tones, from dark shadows to bright highlights—or in other words, a fully expanded histogram.
Low contrast presents no difficulties at all, other than perhaps judgment, as it is a simple matter to drag the white and black points out to the edges. High-contrast images, on the other hand, are always in danger of being clipped, and image-editing tools need some image data to work with. This means getting the exposure right—not necessarily the same thing as getting it averaged.
High-contrast scenes always need special care, even more so than with transparency film. As we saw on the previous pages, the response of a sensor to light is linear. Crudely put, it ...