In photography, HDR refers to “high dynamic range”. Dynamic range is the range of luminance that can be captured in a photo, from the darkest shadows to the brightest highlights.

Unlike the human eye, digital camera sensors (or film in traditional cameras), can only capture a limited dynamic range when photographing scenes with both very bright and very dark areas, such as an interior with a large window. HDR processing creates a 32-bit image which has twice as much information, and therefore many more steps between tones, than an ordinary JPG. This HDR image is then evenly exposed, resolving details in the darkest areas, without losing definition in the brightest areas. And when pushed beyond the “corrective” boundaries, HDR can produce an unreal, plastic, or even “hyper-real” tone, and as such has become a creative technique in itself. Typically, an HDR file needs to be converted back to a 16-bit image format for final output.