Glossary

Paper with a neutral or basic pH (7 or higher). Acid breaks down the molecular chains in paper, causing yellowing and brittleness over time. Museum-grade paper is made from cotton fibers; conservation-grade acid-free paper uses buffered wood-pulp.

Color produced by combining light: red, green, and blue (RGB). Monitors, cameras, and scanners use additive color. All colors combined produce white; no light produces black. See CMYK.

Distortion that occurs when a curved or diagonal line is rendered with square pixels, producing a staircase effect. See Jaggies, Anti-aliasing.

A technique that minimizes aliasing by blending edge pixels with surrounding colors, producing smoother curves and diagonals on screen and in print.

An unintended defect in a digital image, introduced by compression, scanning, or processing. Common forms include jaggies and JPEG blocking.

A defect in which a gradient appears as distinct steps rather than a smooth transition. Can be caused by insufficient bit depth, poor file preparation, or printer limitations.

The machine-readable representation of an ISBN, printed on a book's back cover. KDP and Ingram Spark generate barcodes automatically from the ISBN during upload. See ISBN.

The invisible line on which most letters sit. Descenders — the lower portions of letters like g, p, and y — extend below the baseline. See Type.

The weight in pounds of 500 sheets (one ream) of paper at its standard size. KDP uses 60 lb offset paper for interiors; covers are 10 pt stock.

A mathematically defined smooth curve, controlled by anchor points and handles. The basis of all vector graphics and the pen tool in most design applications.

The number of bits used to represent each pixel. A 1-bit image is black and white only; an 8-bit grayscale has 256 tones; an 8-bit-per-channel RGB image has over 16 million colors.

1) Also called raster: an image made up of individual pixels, each mapped to a specific location and color. 2) In Photoshop, a pure black-and-white (1-bit) image mode. 3) The BMP file format. See Raster.

An image or background color that extends to the edge of the trimmed page. To bleed correctly, artwork must extend at least 0.125″ beyond the trim line on each bleeding edge. The PDF must be sized accordingly — larger than the trim size to include the bleed area.

The minimum rectangle that contains an object. PDFs define several types of page boxes (MediaBox, TrimBox, BleedBox, etc.) that describe different boundaries of a page.

The perceived amount of light emitted or reflected by a color. Distinct from lightness and saturation, though the terms are often used loosely.

The process of adjusting a monitor, scanner, or printer so that what you see matches what will print. Without calibration, soft proofing is unreliable.

The component color layers of a digital image. An RGB image has three channels (red, green, blue); a CMYK image has four. Each channel is a grayscale image representing the intensity of that color across the image.

A vector shape used as a mask to define which parts of an image are visible. Pixels inside the path are included; pixels outside are hidden.

Cyan, Magenta, Yellow, and Black — the four inks used in most commercial printing. Combining CMY theoretically produces black, but in practice a separate black ink is required for depth and contrast. Ingram Spark requires CMYK image files; KDP accepts both RGB and CMYK. See Additive color, RGB.

An unwanted overall tinge of color in an image or printed piece, usually introduced by incorrect scanning, lighting, or color conversion.

The use of profiles and software to maintain consistent color across different devices — monitors, scanners, printers. Effective color management requires accurate calibration and known device profiles. POD platforms do not publish their profiles.

A data file that describes the color characteristics of a specific device or color space. Embedding a color profile in an image file allows other applications and devices to interpret the colors correctly. Also called ICC profile. See Color space.

The process of dividing a full-color image into its CMYK components, each of which prints as a separate layer of ink. In digital printing, this is handled by the RIP.

The range of colors that can be represented within a given color model or by a specific device. RGB color spaces are larger than CMYK — not all colors visible on screen can be reproduced in print. See Gamut.

The process of reducing a file's size. See Lossless, Lossy, JPG.

An image with smooth gradations of tone, such as a photograph. Continuous-tone images must be converted to halftone screens for commercial offset printing.

A proof that serves as a binding agreement between designer and printer — the standard to which the final printed piece will be compared. For POD publishing, an ordered printed proof serves this function.

The range of tonal gradation between the lightest and darkest areas of an image. High contrast images have stark light-to-dark transitions; low contrast images appear flat.

The physical spread of ink dots when ink is applied to paper, causing halftone dots to print larger than intended. The result is a darker, softer image. Standard offset printing assumes about 20% dot gain; digital presses typically run 9–12%.

Dots per inch. Commonly used to describe image resolution, though technically the more accurate term is PPI (pixels per inch). For print, 300 dpi at the intended print size is the standard minimum.

A live effect applied to text or objects that creates the appearance of a shadow cast below. Drop shadows are a source of transparency and must be flattened or handled correctly before printing.

Encapsulated PostScript. A graphics file format based on PostScript that can contain both vector and raster content. When opened in a raster program like Photoshop, vector content is rasterized to pixels.

A simulated bold, italic, or bold italic created by a word processor when the actual font variant does not exist. Faux fonts are visually similar to the real thing on screen but do not exist as printable data — they will fail or be ignored when printed from a PDF.

To merge all layers of an image or document into a single layer, discarding hidden layers and removing transparency. Flattening is destructive — the original layered file should be saved before flattening a copy.

Originally, a complete set of metal type in one typeface and one size. Today used interchangeably with typeface. Technically, a font is one style within a type family — Times New Roman Regular and Times New Roman Italic are separate fonts within the same family. See Type.

Including font data within a PDF so the document displays and prints correctly on any system, regardless of whether the fonts are installed. Most print-on-demand platforms require all fonts to be embedded. Fonts have four embedding permission levels, set by the font's creator: print-and-preview, editable, installable, or no embedding.

Printing using the four process inks: cyan, magenta, yellow, and black. See CMYK.

The complete range of colors that a specific device or color space can reproduce. RGB gamuts are larger than CMYK gamuts — colors outside the CMYK gamut must be remapped when converting for print. See Rendering intent.

A printing defect in which a faint duplicate or shadow of an image appears in an unintended area, caused by uneven ink distribution (mechanical ghosting) or optical effects (optical ghosting).

The visual representation of a character or symbol in a specific font. A single character may have multiple glyphs — for example, a standard lowercase a and an alternate form.

An image mode in which each pixel carries only a luminance value — no color information. Often called black and white. In POD printing, a grayscale image submitted in CMYK may print with colored ink components rather than black ink only. See K-only.

1) The combined inner margins of two facing pages. 2) The space between columns of text. For bound books, the inner (gutter) margin must be wide enough to account for the binding — pages disappear into the spine.

A reprographic technique that simulates continuous tone using a pattern of dots of varying sizes or spacing. Larger dots create darker areas; smaller dots create lighter areas. The basis of all commercial printing of photographic images.

The attribute of a color that makes it identifiable as red, green, yellow, blue, and so on — distinct from its lightness or saturation. In painting, hue means pure color without any tint or shade added.

The page margin on the binding side — between the spine edge and the text block. Inner margins must be wide enough to keep text readable after binding. Required minimums increase with page count. See Gutter.

International Standard Book Number. A unique 13-digit identifier assigned to a specific edition of a book, used for sales, distribution, and cataloging. Each format and edition requires its own ISBN. In the US, ISBNs are sold by Bowker. KDP and Ingram Spark offer free ISBNs, but those tie the platform as publisher of record. See Barcode.

The staircase effect that appears on curved or diagonal edges in a low-resolution or unaliased image. A form of aliasing.

A common image format that uses adjustable lossy compression. Quality and file size can be traded against each other. JPGs do not support transparency. Opening and closing a JPG without saving causes no degradation; opening, saving, and closing compresses the file again, discarding more data each time. For print use, JPGs should be saved at maximum quality.

The adjustment of space between specific pairs of letters to improve their visual fit. Distinct from tracking, which adjusts spacing uniformly across a range of text. Letter pairs like AV and AT are classic kerning candidates.

In CMYK printing, using only the black (K) ink channel — no cyan, magenta, or yellow. A proper K-only grayscale image prints as true black-and-white. A grayscale image that hasn't been converted correctly may print with all four inks, producing a warmer or cooler tone.

A plastic film applied to a printed surface for protection and appearance. Book covers are typically laminated — either matte or gloss. KDP and Ingram Spark offer both finishes.

In image editing and layout software, a separate level on which individual elements can be placed and manipulated independently. Layers must be flattened before final PDF output for most print workflows.

The vertical space between lines of text, measured baseline to baseline. Pronounced "ledding" — the term comes from the lead shims once inserted between rows of metal type. Specified as type size on leading: 12/14 means 12-point type with 14 points of line spacing (2 points of added space). See Point.

A single sheet of paper in a bound book. Each leaf has two sides: a recto (right-hand, odd-numbered) page and a verso (left-hand, even-numbered) page.

Two or more letterforms combined into a single glyph to improve their visual fit. Common ligatures include fi, fl, ff, ffi, and ffl. Some ligatures are applied automatically by OpenType fonts; others (discretionary ligatures) must be enabled manually.

The light-to-dark property of a color, independent of its hue or saturation. Also called value or tone.

The area of a page within which all text and images intended to be read must be contained. For POD interiors, live elements must stay at least 0.25″ inside the trim lines. On covers the safe zone is 0.125″. Anything outside the live area risks being trimmed off.

File compression that reduces size without discarding any image data. TIFF uses lossless compression by default. The image can be decompressed perfectly. See Lossy.

File compression that reduces size by permanently discarding image data. Each save cycle discards more. JPG is the most common lossy format. See JPG, Lossless.

Lines per inch. The frequency of a halftone screen — how many rows of dots per inch. Higher LPI produces finer detail but requires higher image resolution.

A tool that protects specific areas of an image from being altered while allowing other areas to be edited. See Clipping path.

A margin setting that flips the inner and outer margin values between left and right pages, so that both pages of a spread have matching inner and outer margins relative to the spine.

An interference pattern created when two regular patterns overlap at slightly different angles or frequencies. In printing, moiré occurs when halftone screens are misaligned, or when a previously screened image is rescanned.

Numerals designed to sit within text like lowercase letters — with varying heights and descenders — rather than all aligning to a uniform cap height. Also called old-style figures. Preferred for body text; not used in tables. See Type.

A printing process in which the inked image is transferred from a plate to a rubber blanket, then from the blanket to the paper. The standard method for commercial printing. Distinguished from digital printing, in which no plate is involved.

1) A very short last line of a paragraph — a single word or word fragment. 2) The opening line of a paragraph stranded at the bottom of a page. See Widow.

Converting live text to vector outlines, which removes the font data and replaces letters with drawn shapes. This eliminates font-related upload failures and certain POD print anomalies, but makes the text permanently uneditable. A common precaution for final PDF delivery.

Standard book structure: Front matter — half title, title page, copyright page, dedication, table of contents, foreword, preface, introduction. Text — main body, beginning on page 1. Back matter — appendix, notes, glossary, bibliography, index. Front matter pages are typically unnumbered (blind folios) or use Roman numerals. Most books do not include all parts.

Portable Document Format. A file format that preserves layout, fonts, and images regardless of the system used to open it. The standard format for print-ready files submitted to KDP and Ingram Spark. PDF/X-1a is the prepress standard: fonts embedded, transparency removed, all images converted to CMYK.

The binding method used for most paperbacks: pages are gathered, the spine edge is sheared, and a cover is glued around the text block. The three remaining sides are then trimmed. The standard binding for KDP and Ingram Spark paperbacks.

A typographic unit of measure equal to 12 points, or approximately 1/6 of an inch. Used to measure column widths, margins, and other layout dimensions.

Picture element. The smallest unit of a raster image, carrying a single color value at a specific location. Image resolution is expressed as pixels per inch (PPI).

The basic unit of typographic measurement: 1/72 of an inch. Type size is measured in points. Leading is specified as type size on leading — 12/14 means 12-point type on 14-point leading. See Leading, Pica.

A printing model in which books are printed individually as orders are received, rather than in large press runs. Requires digital printing equipment. KDP and Ingram Spark are the dominant POD platforms for self-publishing.

Pixels per inch. The correct term for image resolution. Commonly referred to as DPI, though technically DPI describes the output of a printer (dots per inch), not the resolution of an image. For print, 300 PPI at the intended print size is the standard minimum. See DPI, Resolution.

The process of verifying that a print-ready file meets all requirements before submission: fonts embedded, images at sufficient resolution, no transparency, correct color space, trim size accurate. Most professional layout applications include preflight tools.

All processes that occur between completed layout and printing: typesetting, proofreading, image preparation, color correction, imposition, and file preparation. In POD publishing, prepress is largely the designer's responsibility.

A name used by an author in place of their legal name. Authors may publish under a pseudonym throughout the KDP and Ingram Spark processes; only account registration and tax information require a legal name.

The entity identified as publisher in a book's ISBN registration. When using a platform-assigned free ISBN, the platform (KDP or Ingram Spark) is the publisher of record. Purchasing your own ISBN from Bowker allows you or your imprint to be listed as publisher of record.

An image made up of a grid of pixels, where each pixel is mapped to a specific location and color. File size increases with image dimensions. JPG, TIFF, PNG, PSD, and BMP are raster formats. See Bitmap, Vector.

The method used to handle out-of-gamut colors when converting from RGB to CMYK. Four ICC-standard intents: Perceptual (compresses all colors, preserving overall appearance — usually best for photographs), Relative Colorimetric (maps in-gamut colors exactly, clips out-of-gamut), Absolute Colorimetric (preserves exact values, clips out-of-gamut), Saturation (prioritizes vivid color over accuracy — best for charts and logos).

The number of pixels or dots per inch in an image or output device. For print, the question is whether an image has enough pixels to reproduce well at its intended size — a number alone tells you nothing without knowing the print dimensions. 300 PPI at the intended print size is the reliable minimum for most book work; fine line art and text rendered as images benefit from 600–800 PPI.

Red, Green, Blue — the additive color model used by monitors, cameras, and scanners. RGB color spaces are larger than CMYK and cannot be fully reproduced in print. KDP accepts RGB image files; Ingram Spark requires CMYK. See CMYK, Color space.

A black made from all four CMYK inks combined, producing a denser, deeper black than K alone. Standard Photoshop rich black is C75 M68 Y67 K90. Rich black requires precise registration and is generally not recommended for body text.

Raster Image Processor. The hardware or software that converts a print-ready file into the dot pattern a printer outputs. The RIP interprets vector data (type, paths), applies color profiles, handles dot gain compensation, and screens the image for printing.

The intensity or purity of a color relative to its brightness. A fully saturated color contains no gray; a fully desaturated color is neutral gray. See Hue, Lightness.

Serif typefaces have small finishing strokes (serifs) at the ends of letterforms. Sans serif typefaces do not. Body text in books is traditionally set in a serif face; sans serif is common for display and heading use. See Type.

A folded sheet that forms a section of a book's pages. Folded once, a signature contains four pages; twice produces eight, and so on. Signatures are gathered in order before binding. In POD publishing, the printer handles imposition — designers work in single-page or two-page spreads.

An on-screen simulation of how a file will print. Reliable soft proofing requires a calibrated monitor, correct ambient lighting, and the output device's ICC profile. POD platforms do not publish their profiles, which limits soft proof accuracy.

The bound edge of a book connecting front and back covers. Spine width is calculated from page count and paper type. Standard spine orientation in the US and UK: when the book lies face-up, spine text reads left to right.

Two facing pages viewed together. Left-hand (verso) pages are even-numbered; right-hand (recto) pages are odd-numbered. Chapter openings traditionally begin on a recto page.

Tagged Image File Format. A raster image format that uses lossless compression by default, making it suitable for archival and print use. TIFF files are typically large but preserve full image quality.

Total Ink Coverage / Total Area Coverage. The sum of all CMYK ink percentages on a given area. If all four inks print at 100%, TIC is 400%. Excessive ink causes offsetting, slow drying, and wet paper. Recommended maximums vary by press and paper type.

Uniform adjustment of letter spacing across a range of text. Distinct from kerning, which addresses specific letter pairs. Tight tracking reduces space throughout; loose tracking opens it up.

Objects or effects that allow underlying elements to show through. Sources include reduced opacity, blending modes, drop shadows, and feathering. Transparency must be flattened before printing from most PDF workflows. Improper flattening can cause color shifts, stitching lines, and other artifacts.

The finished dimensions of a book after trimming, expressed as width × height — for example, 6 × 9. All page setup, margins, and image placement are calibrated to the trim size. The most common trim size for fiction is 6 × 9; nonfiction commonly uses 6 × 9 or 7 × 10.

A typeface is a family of related fonts — Times New Roman, Garamond, Helvetica. A font is one specific style and size within a family: Times New Roman Italic is a separate font from Times New Roman Regular. Fonts come in three main formats: TrueType, OpenType, and PostScript. OpenType supports up to 65,000 characters; TrueType and PostScript support 256. All three formats are cross-platform compatible on modern systems.

A sharpening technique that increases edge contrast by combining the original image with a blurred, inverted version of itself. The result is increased apparent sharpness without actual new detail. Excessive unsharp masking produces visible halos around edges.

Graphics described mathematically using points, lines, and curves rather than pixels. Vector art is resolution-independent — it can be scaled to any size without quality loss. Type is vector. EPS, SVG, and AI are vector formats. See Raster, Bézier curve.

A gradient applied to the edge of an image or shape, fading it to transparency. When applied to a shape or selection, it is called feathering. Vignettes are a source of transparency and must be handled correctly before printing.

A widow is the last line of a paragraph that begins a new page. An orphan is either a very short last line of a paragraph (a word or partial word) or the opening line of a paragraph stranded at the bottom of a page. Both are typographic problems. Automatic widow/orphan control in word processors eliminates them by creating unequal page depths — a cure that introduces its own problems in professional book design.

What You See Is What You Get. The principle that on-screen display accurately represents printed output. Reliable in most professional layout workflows; less reliable in word processors and when soft proofing without calibrated equipment.