Operation Manual

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Appendices
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Appendices— Appendix B
Term Defi nition
Crop The selected portion of an image.
Curve See Tone Curve.
dpi dots per inch, a measure of resolution. The more dots per inch, the higher the resolution. See also ppi, Resolution.
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 pos-
sible 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 (moni-
tor or printer), or color profi le. 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 (fi lm transparencies and color monitors) is very different from, and comple-
mentary to, the gamut of secondary CMYK (Cyan, Magenta, Yellow, and blacK) re fl ect ed light displays (printed materials). See
also CMYK, Profi le, RGB.
Halo width
The extent of pixels around a selected central pixel affected when Unsharp Mask is applied. Also referred to as “radius.” In-
creasing 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.
Histogram
A bar graph showing the distribution of tones or chroma in an image. The horizontal axis shows tone level (bright ness) or chro-
ma, the vertical axis the number of pixels. The bars in the graph show the num ber of pixels of a given brightness or chroma in
the image. The histograms displayed in the “Curves” and “LCH Editor” palettes shows the distribution for the selected chan-
nel, and can be used for ref er ence when editing curves. See also Tone, Tone curve.
ICC
The International Color Consortium, an international organization working to develop stan dards for color management and
color management profi les. ICC profi les were developed for the conversion of color space information between devices, and
are now on their way to becoming a global standard. ICC profi les have been proposed as an International Or ga ni za tion for
Standardization (ISO) standard. See also Profi le.
Gray point Controls the output level for mid-tones in the original image. See also Tone, Tone cur ve.
Firewire Apple’s term for the IEEE 1394 interface. See IEEE 1394.
Grayscale
A color model reproduces image data in shades of gray. Eight-bit grayscale supports 256 shades, sixteen-bit grayscale 65,526
shades. See also Bit depth.