Hairline (Rule)
Subjective term referring to very small space, thin line or close register. The meaning depends on who is using the term and in what circumstances.

Half-scale Black
Black separation made to have dots only in the shadows and midtones, as compared to full-scale black and skeleton black.

Halftone
(1) To photograph or scan a continuous tone image to convert the image into halftone dots.

Halftone Screen
Piece of film or glass containing a grid of lines that breaks light into dots. Also called contact screen and screen.

Halo Effect
Faint shadow sometimes surrounding halftone dots printed. Also called halation. The halo itself is also called a fringe.

Hard Dots
Halftone dots with no halos or soft edges, as compared to soft dots.

Hard Mechanical
Mechanical consisting of paper and/or acetate and made using paste-up techniques, as compared to electronic mechanical.

Head(er)
At the top of a page, the margin.

Head-to-tail
Imposition with heads (tops) of pages facing tails (bottoms) of other pages.

Heat-set Web
Web press equipped with an oven to dry ink, thus able to print coated paper.

Hickey
Spot or imperfection in printing, most visible in areas of heavy ink coverage, caused by dirt on the plate or blanket. Also called bulls eye and fish eye.

High-fidelity Color
Color reproduced using six, eight or twelve separations, as compared to four-color process.

High-key Photo
Photo whose most important details appear in the highlights.

Highlights
Lightest portions of a photograph or halftone, as compared to midtones and shadows.

Hinged Cover
Perfect bound cover scored 1/8 inch (3mm) from the spine so it folds at the hinge instead of, along the edge of the spine.

HLS
Abbreviation for hue, lightness, saturation, one of the color-control options often found in software, for design and page assembly. Also called HVS.

Hot Spot
Printing defect caused when a piece of dirt or an air bubble caused incomplete draw-down during contact platemaking, leaving an area of weak ink coverage or visible dot gain.

House Sheet
Paper kept in stock by a printer and suitable for a variety of printing jobs. Also called floor sheet.

Hue
A specific color such as yellow or green.