EPS & graphics glossary

39 plain-English definitions of the terms you will meet when working with EPS and vector files.

Design and print vocabulary is unusually unforgiving: a printer asks for bleed, a designer mentions outlining your text, a converter warns that transparency will be flattened, and none of it means much until someone explains it plainly. These are the terms that come up most often in our support email, defined without jargon.

If you are starting from scratch, read What Is an EPS File? first, then come back here for anything unfamiliar. For the technical detail behind the EPS-specific entries, see The EPS File Format Explained.

File formats

EPS (Encapsulated PostScript): A vector graphics format that stores artwork as a self-contained PostScript program. Designed to be embedded inside another document — a brochure, a report — and scaled without quality loss. Introduced in the late 1980s and still widely used for logos and print artwork.
PostScript: Adobe's page-description language, released in 1984, that tells printers and renderers how to draw a page. It is a real programming language: stack-based and postfix, so operands come before operators. An EPS is a single encapsulated PostScript graphic.
SVG (Scalable Vector Graphics): An XML-based vector format built for the web. Lightweight, infinitely scalable, styleable with CSS and animatable with JavaScript. The best choice for logos and icons on a website.
AI (Adobe Illustrator): Illustrator's native working file, with every layer and effect still editable. Best kept as the master copy and exported to other formats for sharing. Modern .ai files are PDF-compatible, which is why some other applications can open them.
PDF (Portable Document Format): PostScript's successor and a universal container that can hold vectors, embedded fonts, raster images and multiple pages. Opens almost anywhere and is preferred by modern print workflows.
PNG: A lossless raster format supporting full alpha transparency. The right target when converting an EPS logo for screen use.
JPG / JPEG: A lossy raster format built for photographs. It has no transparency and its compression damages the hard edges and text that vector artwork is usually made of.

Core concepts

Vector graphic: An image defined by mathematical paths — points, lines and curves. Because it is maths rather than pixels, it is redrawn at full quality at any size. See our guide on vector vs raster.
Raster graphic: An image made of a fixed grid of coloured pixels. Excellent for photographs, but it has one native resolution and blurs when enlarged past it.
Rasterize: To convert vector artwork into pixels at a chosen resolution — for example exporting an EPS to PNG. The step is one-way: the mathematical description is discarded.
Resolution independence: The property of vector formats whereby no resolution is stored at all, so output quality depends only on the device rendering the file.
Bézier curve: The curve type vector formats use, defined by anchor points and control handles that determine how the line bends between them.
Anchor point: A defined point along a path. Dragging anchor points and their handles is the fundamental act of vector editing.
Path: A sequence of anchor points and the curves between them. A path may be open, like a line, or closed, like a rectangle.
Stroke and fill: A stroke is the outline drawn along a path; a fill is the colour inside a closed one. Strokes are centred on the path, so half the stroke width sits outside the shape — a frequent cause of clipped artwork.
Clipping path: A shape that masks artwork, hiding everything outside it. Used to crop images to a non-rectangular outline.

Inside an EPS file

Bounding box: The %%BoundingBox header line declaring the artwork's extents in points. Host applications trust it completely, so a wrong value produces artwork that appears cropped or surrounded by unexpected white space.
Point: The unit PostScript works in: 1/72 of an inch. A 72×72 point graphic is exactly one inch square.
DSC (Document Structuring Conventions): The %% comment lines carrying metadata such as %%BoundingBox, %%Creator and %%Title. They are comments to the language but metadata to the applications reading the file.
Preview thumbnail: A small low-resolution bitmap (usually TIFF or WMF, typically 72 DPI) embedded so layout software can display something without running the PostScript. This is the real reason an EPS often looks blurry on screen while printing perfectly sharp.
Encapsulation: The set of restrictions that make an EPS safe to embed. It may not use operators that alter global state, such as setpagedevice or initclip, because doing so would corrupt the document hosting it.
Ghostscript: A free PostScript and PDF interpreter that Inkscape, GIMP and many document viewers use to read EPS. If a desktop application opens your EPS as a blank or grey box, Ghostscript is usually what is missing.
Flattening: Converting transparency effects into opaque shapes. EPS has no transparency, so drop shadows and glows must be flattened on export — which is why they are no longer editable and sometimes show faint seams.

Colour

CMYK: The four-ink subtractive colour model (Cyan, Magenta, Yellow, Black) used by printing presses. Looks duller on screen than RGB, which is expected rather than a fault.
RGB: The additive Red-Green-Blue model used by screens. Brighter and wider-ranging than CMYK, and the right choice for anything viewed on a display.
Spot colour: A pre-mixed ink, such as a Pantone, printed on its own plate rather than built from CMYK. Used for exact brand colours. It has no true RGB equivalent and is always approximated on screen.
Gamut: The range of colours a device or model can reproduce. RGB and CMYK gamuts differ, so some screen colours simply cannot be printed.
Colour profile (ICC): Data describing how a file's colour numbers map to actual appearance. A mismatched or missing profile is a common cause of colours that look wrong rather than merely duller.
Overprint: A print setting where one ink prints on top of another instead of knocking it out. Wrong overprint settings can make artwork vanish or darken unexpectedly on press.

Output and print

DPI / PPI: Dots or pixels per inch, a measure of raster resolution. Pixels needed = physical size in inches × DPI. Vector files have no DPI until they are rendered.
Transparency and alpha channel: See-through areas of an image. The alpha channel stores how opaque each pixel is. PNG, SVG and PDF support it; JPG and EPS do not.
Anti-aliasing: Softening the stepped edges of rasterized artwork by blending edge pixels with the background. It is why a rasterized logo cannot be cleanly recoloured afterwards.
Lossless compression: Compression that preserves every detail, as PNG does. Re-saving never degrades the image.
Lossy compression: Compression that discards data to save space, as JPG does. Every re-save compounds the damage, so always re-export from the original.
Bleed: Artwork extended past the trim edge, normally by 3 mm, so that trimming never leaves a white sliver at the paper's edge.
PDF/X: A family of PDF profiles built for printing, such as PDF/X-1a and PDF/X-4. Many print shops require one; a plain conversion does not produce it.
Outlining text: Converting fonts into vector shapes so the artwork no longer depends on the font being installed. It guarantees correct rendering but makes the text permanently uneditable.
Font embedding: Storing the actual font data inside the file so it renders identically elsewhere. PDF supports this well; an EPS that neither embeds nor outlines its fonts will have them substituted on another machine.
Tracing / vectorizing: Analysing a raster image to generate vector paths approximating it. It works acceptably on high-contrast flat-colour images and poorly on photographs, soft gradients and small text.