High Dynamic Range Imaging - Photography

Photography

In photography, dynamic range is measured in EV differences (known as stops) between the brightest and darkest parts of the image that show detail. An increase of one EV or one stop is a doubling of the amount of light.

Dynamic ranges of common devices
Dynamic ranges of common devices
Device Stops Contrast
LCD display 9.5 700:1 (250:1 – 1750:1)
DSLR camera (Canon EOS-1D Mark II) 12 2048:1
Negative film (Kodak Vision3) 13 128:1
Human eye 10–14 1024:1 – 16384:1

High-dynamic-range photographs are generally achieved by capturing multiple standard photographs, often using exposure bracketing, and then merging them into an HDR image. Digital photographs are often encoded in a camera's raw image format, because 8 bit JPEG encoding doesn't offer enough values to allow fine transitions (and introduces undesirable effects due to the lossy compression).

Any camera that allows manual over- or under-exposure of a photo can be used to create HDR images. This includes film cameras, though the images may be digitized for processing with software HDR methods.

Some cameras have an auto exposure bracketing (AEB) feature with a far greater dynamic range than others, from the 3 EV of the Canon EOS 40D, to the 18 EV of the Canon EOS-1D Mark II. As the popularity of this imaging method grows, several camera manufactures are now offering built-in HDR features. For example, the Pentax K-7 DSLR has an HDR mode which captures an HDR image and then outputs (only) a tone mapped JPEG file. The Canon PowerShot G12, Canon PowerShot S95 and Canon PowerShot S100 offer similar features in a smaller format. Even some smartphones now include HDR modes.

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