H
 

H & V lock time

The length of time it takes for a device to lock to horizontal and vertical sync.

H (Horizontal)

Horizontal Period or Rate, Line of Video Information or Horizontal Sync Pulse

Hairline:

A very thin line or gap about the width of a hair or 1/100 inch.

Halftone

If you take a black and white photograph it is made up of not just black and white but lots of different greys. To recreate the greys just by using black ink the image is broken down into a regular pattern of dots which vary in size depending on the darkness of grey they are recreating. The darker the grey, the larger the dots. In order to make the screened image look more like a continuous tone image the dots are kept as small as possible. However, restrictions in the printing process govern the minimum size of dot that can be reproduced. Color images are screened in the same way except they are created from four colors so each color is screened separately and overprinted to create the desired effect. The frequency of the halftone screen is known as the screen ruling and is specified as lines per inch (lpi) or lines per centimeter (lpc). For offset litho printing (used for the vast majority of print) the screen is normally set at between 150lpi and 200lpi, although for fine art work it can be much higher.

Halftone:

Converting a continuous tone to dots for printing.

Handle

An extra number of frames attached to the head and tail of an optical print as a safety precaution. (Laboratory)

Hard copy:

The output of a computer printer, or typed text sent for typesetting.

Hard disk

A digital data storage device using a rigid, magnetic disk.

Hard Disk

A data storage and retrieval device consisting of a disk drive and one or more permanently installed disks. Increasingly common for storing sound effects and archiving for future use.

Hard white clip

Stops the composite video going above a predetermined level.

Harmonic

A periodic wave having a frequency that is an integral multiple of the fundamental frequency. For example, a wave with twice the frequency of the fundamental frequency is called the second harmonic.

Harmonic Distortion

Acoustic distortion characterized by unwanted changes between input and output at a given frequency. (Acoustics)

Harmonic distortion

The production of harmonics at the output of a circuit when period wave is applied to its input. The level of the distortion is usually expressed as a percentage of the level of the input.

HDTV

High-definition television.

Hertz (Hz)

Unit for measuring frequency of d signal; formerly called "cycles per second."

Hexachrome

The four color print process is quite limited in the number of colors it can reproduce. Adding two additional colors, orange and green, allows a much wider range of colors to be reproduced. Hexachrome is a six color printing process using the traditional four process colors: black, magenta, yellow, cyan; plus orange and green. Images with oranges and greens tend to benefit most from hexachrome printing, that's why you will usually see demonstration images are bowls of fruit or plants! Beware, though, because hexachrome printing presents increased registration problems and for additional material and make-ready times.

Hickey:

Reoccurring unplanned spots that appear in the printed image from dust, lint, dried ink.

High frequency (HF)

The frequency bands from 3 to 30 MHz.

High frequency loss

Loss of signal amplitude at higher frequencies, caused for example, by passing a signal through a coaxial cable.

High-bulk paper:

A paper made thicker than its standard basis weight.

Highkey

An overall brightly lit scene with relatively few shadows. (Lighting)

Highlight:

The lightest areas in a picture or halftone.

High-Pass Filter

An electronic filter used in various audio circuits to attenuate all frequencies below a chosen frequency.

High-Z looping input

A high-impedance input circuit which also includes an output to enable routing the signal to another piece of equipment.

Hiss

Asperity Noise. Noise caused by minute imperfections in the recording medium (tape). (Sound)

HMI

An enclosed, AC mercury arc lamp. (Lighting)

Horizontal resolution

Chrominance and luminance resolution (detail) expressed horizontally across a picture tube. This is usually expressed as a number of black to white transitions or lines that can be differentiated. Limited by the bandwidth of the video signal or equipment.

Hum-bucker

A circuit (often a coil) that introduces a small amount of voltage at power-line frequency into the video path to cancel unwanted ac hum.

Hybrid DVD

hybrid DVD -- A general term for a DVD-Video disc that contains both video and computer content. See also enhanced DVD.

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