Editing Zone System (section)

=== Digital photography ===

The Zone System can be used in digital photography just as in film photography; Adams (1981, xiii) himself anticipated the digital image. As with color reversal film, the normal procedure is to expose for the highlights and process for the shadows.

Until recently, digital sensors had a much narrower dynamic range than color negative film, which, in turn, has less range than monochrome film. But an increasing number of digital cameras have achieved wider dynamic ranges.  One of the first was [[Fujifilm]]'s [[FinePix S3 Pro]] digital SLR (released in 2004), which has their proprietary "[[Super CCD]] SR sensor" specifically developed to overcome the issue of limited dynamic range, using interstitial low-sensitivity photosites (pixels) to capture highlight details.{{Citation needed|date=May 2009}} The [[Charge-coupled device|CCD]] is thus able to expose at both low and high sensitivities within one shot by assigning a honeycomb of pixels to different intensities of light.

Greater scene contrast can be accommodated by making one or more exposures of the same scene using different exposure settings and then combining those images. It often suffices to make two exposures, one for the shadows, and one for the highlights; the images are then overlapped and [[Tone mapping|blended appropriately]], so that the resulting composite represents a wider range of colors and tones. Combining images is often easier if the [[Digital image editing|image-editing]] software includes features, such as the automatic layer alignment in Adobe [[Photoshop]], that assist precise registration of multiple images. Even greater scene contrast can be handled by using more than two exposures and combining with a feature such as Merge to [[high-dynamic-range imaging|HDR]] in Photoshop CS2 and later. A simplified approach has been adopted by [[Apple Inc.]] as a selectable HDR option in later versions of the [[iPhone]].

The tonal range of the final image depends on the characteristics of the display medium.  Monitor [[contrast ratio|contrast]] can vary significantly, depending on the type ([[Cathode-ray tube|CRT]], [[LCD]], etc.), model, and [[Color calibration|calibration]] (or lack thereof). A [[computer printer]]'s tonal output depends on the number of [[ink]]s used and the [[photographic paper|paper]] on which it is  printed. Similarly, the density range of a traditional [[photographic print]] depends on the [[List of photographic processes|process]]es used as well as the paper characteristics.

==== Histograms ====

Most high-end digital cameras allow viewing a [[image histogram|histogram]] of the tonal distribution of the captured image. This histogram, which shows the concentration of tones, running from dark on the left to light on the right, can be used to judge whether a full tonal range has been captured, or whether the exposure should be adjusted, such as by changing the [[exposure time]], lens [[aperture]], or [[ISO speed]], to ensure a tonally rich starting image.<ref name="Histograms and the Zone System">[http://www.illustratedphotography.com/basic-photography/zone-system-histograms Discussion on how histograms can be used to implement the Zone System in digital photography] ([https://web.archive.org/web/20120501173208/http://www.illustratedphotography.com/basic-photography/zone-system-histograms archived 2012-05-01])</ref> A technique called [[ETTR]] (exposing to the right) based on histogram reading rather than exposure metering is shown to be more appropriate for digital sensors to extract more visual information out of them for further processing in editing.