H

Halftone Screen : A pattern of tiny dots that is used for printing an image to simulate continuous tones.
Hard Proof : The printed proof of a document created to preview how colors will look when reproduced on a specific output device, usually a commercial printing press. A hard proof may be produced using a laminate contract proofing system (e.g., Imation MatchPrint) or a tightly calibrated digital printer designed for proof creation.
Highlight : The area of a glossy object over which specular reflection can be viewed. It is normally the color of the light source, not of the object.
Histogram : A graph showing the number of pixels at each level of brightness in an image.
HSB : A three-coordinate, device-independent color model. The HSB coordinates define colors in terms of Hue, Saturation, and Brightness.
HSL/Hue-Saturation-Lightness : HSL, also known as HSI (Hue-Saturation-Intensity) is a color space used to represent images. HSL is based on polar coordinates, while the RGB color space is based on a three-dimensional Cartesian coordinate system. Intensity is the vertical axis of the polar system, hue is the relative angle and saturation is the planar distance from the axis. HSL is thought to be more intuitive to manipulate than RGB space. For example, in the HSI space, to change red to pink requires only changing the saturation parameter.
HSV/Hue-Saturation-Value : A color space that describes color using three basis components: hue, saturation and brightness.
Hue : The wavelength of light of a pure color that gives a color its name--such as red or blue--independent of its saturation or brightness.