AEB Mode

DSLR and mirrorless cameras, as well as some compact digital cameras, offer Automatic Exposure Bracketing. This feature enables you to automatically take three or more exposures in a row: one at the proper exposure, one or more underexposed, and one or more overexposed.

Aperture Priority

In Aperture Priority mode, you select the aperture and the camera determines the correct shutter speed for the available light. The shutter speed also depends on ISO sensitivity. This is the correct mode for shooting bracketed shots for HDR (refer to Section 1 for more information).

Bit

Bits represent digital data in computers. Digital Images are made of bits. A bit depth corresponds to 2^(Bit Depth) levels (e.g. 256 for 8-bit).

Bit Depth

The number of bits a file type uses to represent a pixel's color at a given location in an image.

Bracketed Images

A group of photos taken with the Automatic Exposure Bracketing function of a camera, resulting in photos of the same scene taken with different exposures.

Chromatic Aberration

As the lens focuses different wavelengths slightly differently, chromatic aberration occurs. For example, the purple fringing you often find around edges (as with leaves in front of a bright sky).

Contrast Ratio

Another way to describe the dynamic range of a scene. The ratio between the darkest and brightest areas.

DSLR

Digital Single Lens Reflex camera.

Dynamic Range

In the context of photography, the total range of light intensity in a scene, from the deepest shadows to the brightest highlights.

EXIF

The Exchangeable Image File header contains information about the image, the camera, location, date and time and camera settings.

Exposure

The amount of light that enters a camera for the length of time the shutter is open. Exposure depends on aperture and shutter speed, as well as the camera’s sensitivity to light (controlled by the ISO). "Exposure" is also shorthand for a photograph or frame (a frame of film).

Exposure Fusion

A family of HDR Styles / Methods, based on combining bracketed photos in such a way that highlight details are taken from the underexposed photos and shadow details from the overexposed ones.

EV (Exposure Value)

A measure of exposure which is the equivalent of a stop. In the absolute sense, EV is defined as the exposure from a photo taken at 1 second, f/1, and ISO 100. In the relative sense, the correct exposure is normally 0 EV and any deviation is measured in positive or negative EV from that mark.

HDR

High Dynamic Range. A scene has High Dynamic Range when the lighting intensity differences in the scene are large.

HDR Image

Strictly speaking, an HDR image is an intermediary image with 32 bits per color channel (96 bits per pixel). Such an HDR image is the result of merging photos of the same scene taken under different exposure settings, and storing the high dynamic range output in a special HDR image format. This 32-bit intermediary HDR image must be adjusted using an HDR Tone Mapping method, to enable proper display on standard monitors, or when printed. It has become very common to speak of an "HDR image" as the image file that results from HDR Tone Mapping the intermediary 32-bit HDR image. But this is not technically correct, as the "HDR image" is in fact the 32-bit input file, in the formal terminology of an HDR processing work flow.

Histogram

Histograms represent brightness distribution in digital images. They help evaluate correct exposure. The y-axis represents the amount of pixels and the x-axis represents the brightness value.

JPG

A common image file format with two primary strengths – a relatively small file size and universal compatibility. JPEGs use a lossy compression scheme and should not be edited and re-saved.

Noise

Statistical variations inherent in the sensor system cause noise. Noise is always present, but higher sensitivities and smaller sensors usually generate more noise.

Pixel

Digital pictures consist of pixels, the smallest units. Each pixel has a color that can be represented by 8 or 16 bits or as a floating-point number (32bit HDR).

PPI

Pixels per Inch. Can be used to describe the actual pixels per inch of a print. Often confused with DPI (Dots per Inch), used by color printers to print an image.

RAW Image

A file containing the raw data from the camera sensor. Raw files do not have a color profile or other stylistic preferences permanently applied.

TIFF

A comprehensive image format that offers lossless compression schemes for smaller file sizes with higher quality. This format is suitable for editing and printing but not publishing on the Web.

Tone Mapping

A family of HDR Styles / Methods for adjusting a 32-bit merged HDR image into an image that can be properly viewed on monitors and when printed.