Nikon 4 user manual 150, Compression

Appendix E

Compression

A method for reducing file sizes for storage or transmission. Compression algorithms can be divided into “lossless” algorithms, such as LZW, in which no information is lost when files are restored to their original size for display or editing, and “lossy” algorithms, such as JPEG, in which some information is lost when the file is restored. See also JPEG, TIFF.

Crop

The portion of the image selected in an image window.

Curve

See Tone Curve.

Eyedropper

A tool for sampling white point, black point, or midpoint. See also Black point, Midpoint, White point.

FireWire

Apple’s term for the IEEE 1394 interface. See IEEE 1394.

Fisheye lens

A “fisheye” lens is any lens with a view angle of 180 degrees or more. Fisheye lenses may have a view angle of 180 degrees in all directions or only diagonally. Distortion increases towards the edges of the picture, with little or no distortion at the center of the image. The Fisheye Lens palette in Nikon Capture 4 can be used to reduce distortion in images taken with an AF DX Nikkor ED 10.5 mm f/2.8G lens to create an image close to what would be produced by an ordinary wide-angle lens.

Gamma

Gamma (also written “γ”), a fundamental property of video systems, determines the intensity of the output signal relative to the input. When calculating gamma, the maximum possible input intensity is assigned a value of one, and the minimum possible intensity (no input) is assigned a value of zero. Output is calculated by raising input to the inverse of the gamma value (output = input( 1/γ ) ).

Gamut

The range of colors that can be expressed by a given input device (for example, scanner or digital camera), output device (monitor or printer), or color profile. No gamut can reproduce all of the colors seen by the human eye. The gamut of primary RGB (Red, Green, and Blue) transmitted light displays (film transparencies and color monitors) is very different from, and complementary to, the gamut of secondary CMYK (Cyan, Magenta, Yellow, and blacK) re- flected light displays (printed materials). See also CMYK, Profile, RGB.

Gray point

See Midpoint.

Halo width

The extent of pixels around a selected central pixel affected when Unsharp Mask is applied. Also referred to as “radius.” Increasing the halo width increases the width of edges affected by Unsharp Mask. Excessive application of Unsharp Mask results in an undesirable halo along edges in the image. See also Unsharp Mask.

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