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. (2) A photograph or continuous-tone illustration that has been halftoned and appears on film, paper, printing plate or the final printed product.

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.