Prepress & Imposition Glossary: Print Production Terms Explained

Ever wonder what happens to your graphic design after you “export”? Where does it go, between your computer and the million-dollar printing press?

In commercial printing, the steps between file delivery and production can determine whether a job runs smoothly or results in costly errors. Prepress workflow in print production acts as the high-stakes bridge connecting digital pixels to physical paper. If a file isn't prepared perfectly, small digital oversights transform into thousands of dollars of wasted paper, incorrect colors, and ruined print runs.

To ease production and print buyers’ entry into the commercial design and printing world, this glossary explains essential prepress, print production, and imposition terms in clear language. We hope this new resource assists you in navigating the exciting world of commercial printing.

What Is Prepress?

Prepress is the term for all the steps undertaken from the completion of a print layout to the step of printing it on a press. The pre-press stage of printing is very similar to the gatekeeping process of a quality check. It enables everything to be automated and coordinated in a way that satisfies the limitations of a printing press. 

It is also the stage of designing in which the digital files are turned into press data, along with the press plates and proofs.

Essential Prepress Terms

Preflight checking: The crucial initial diagnostic scan of digital files to identify potential printing errors (like missing fonts, low-resolution images, or incorrect color spaces) before the job goes to production.

Plate / Platemaking: A printing plate carries the image used during production. With offset lithography, the image is transferred from the plate to a rubber blanket, from where the image is further transferred to the paper. Plate materials and imaging methods works different according to the printing process.

RIP (Raster Image Processor): This refers to the software or hardware that converts print files, processes fonts, images, transparency, screening, color separations, and transforms the page into raster data for plate setting or digital printing. 

Resolution: The resolution of a raster image is described in terms of pixel density, i.e., the number of pixels per inch, PPI. According to the standard for printing high-quality commercial graphics, the resolution should be 300 PPI for the printout; however, this is just an approximation. The required resolution depends on the printing method, image type, viewing distance, and line screen.

Material: The ink can be printed on paper, cardboard, vinyl, and many other materials.

Trapping: A prepress technique that slightly overlaps adjoining colors to prevent visible white gaps caused by minor registration variation during printing. 

Computer-to-Plate, or CTP: A platemaking workflow in which digital page data is imaged directly onto a printing plate without first producing film. 

File Preparation and Artwork Terms

Designs must be aligned to a specific margin and must allow an adequate amount of room for any changes that might be made to a design to prepare the file for printing.

Bleed and crop marks: A bleed is an area of a printed design that has been extended to prevent an unprinted edge from showing. Crop marks designate where the printed paper is to be cut. Bleeds are usually 1/8 inch (or 3mm) beyond the crop marks.

Slug Area: This is outside the bleed area. It gets cut with scrap paper. Production notes provide some guide to provide the details to design

Live Area / Safe Zone: To avoid accidental trimming, the space within the trim line where necessary texts, logos, and other critical elements of the document must go.

Rich Black vs. Plain Black: While plain black is usually made up of one ink color (usually black separation) like 100% K, rich black is made up of black with certain combinations of CMY colors. The specific formula and maximum ink level must be determined from the printer because the requirements differ from press to press, from paper to paper, and from color profiles.

Transparency Flattening: It is the process of converting the overlapped transparent artwork to printable vector/raster elements when the output system cannot handle live transparency.

Outlining Fonts (Converting to Curves): Process of converting text into vector shapes that appear independent of the fonts used. While outlining avoids problems with missing fonts, it makes text hard to edit and removes the font information. Font embedding should be considered whenever the printer can handle that process.

Artboard: Artboard is the area in which your design exists in the vector graphics software.

Vector Graphics: This kind of graphics uses paths, so it is resolution independent and can be scaled to any size.

Raster Images: Raster images consist of a fixed grid of colored dots.  Because of this, these images can’t be scaled to a larger size than normal without a decrease in picture quality.

Color and Image Terms

These printing terms for design with CMYK process printing can help with understanding the cause of a lackluster print when you expect a vibrant result.

CMYK: Refers to the 4 process colors in printing: Cyan, Magenta, Yellow, and Key (Black). Process colors: 

RGB: A system in which red, green, and blue colors are mixed to form an image. The RGB colors may have to be converted according to the printer's needs and color management process into the CMYK or output colors.

Color separation: Normal process printing consists of cyan, magenta, yellow, and black separations, and some work also includes spot colors, white ink, varnishes, coatings, or expanded gamut ink.

Spot Color: An ink that is premixed and printed with its own separation. Spot colors can be used alone or in combination with process inks when exact brand colors, metallics, fluorescents, or other special effects are needed.

Registration marks: These are used to show where a printing plate should line up. The printer will align all the plates to a registration mark.

Color Profile (ICC): These are assigned to a device in order to help that device accurately display and reproduce the correct colors.

Terms for Quality Control and Proofing

Soft Proof: Proofing of artwork as it would look using the chosen output profile on screen. The accuracy of this proofing depends on how calibrated the monitor, viewing conditions, software settings, and device are. 

Hard Proof / Contract Proof: A physical proof produced to an agreed standard or specification and color managed. Once approved, it can be the visual reference for expected color during production.

Press Proof: A sample that is printed through the full process with production ink, plates, and paper. It’s a very accurate sample, but because of the setup, it’s only used for special high-volume projects.

Color Bar: A color measurement tool that contains patches of colors that are printed on the edge of the production printing sheets. It helps an operator measure the consistency of the ink used throughout the printing process.

Densitometer: A device used by press operators to measure the optical density of printed ink or film, and thus help them maintain ink strength and consistency. 

Spectrophotometer: An instrument for measuring the spectral reflectance or transmission of a color. Measurements can be transformed to standard colour values and compared to targets or tolerances.

What Does Imposition Mean in Printing?

A layout of pages or repeating patterns on a press sheet to make sure they are in the right order and orientation after printing, folding, cutting, and binding. Imposition can also result in better paper utilization and production efficiency.

When you fold up a massive blank sheet that includes multiple printed pages, those pages get all jumbled up. Fortunately, some printing software knows how to figure out where each page needs to go, even if pages need to be printed upside down, to make sure the finished product is an actual booklet.

Important Imposition Terms

Parent Sheet: A parent sheet is generally the large, uncut sheet supplied by a paper manufacturer or merchant 

Press Sheet: A press sheet is the sheet size prepared or used for a particular press run. 

Signature: A printed press sheet, with multiple pages, that is folded into a definite page sequence before gathering, sewing, stitching, or binding. Some of the signature counts are 8, 16, and 32, but other numbers can also apply. 

Pagination: The numbering and sequence of pages in a publication.

Creep: The gradual outward displacement of the inner pages in a folded and nested publication, especially in saddle-stitched work. Imposition software compensates for creep by shifting page content according to its position in the signature and the thickness of the stock. 

Gripper Margin: The area of the edge of the printed sheet that cannot contain image or text. The edge gets held by a mechanical clamp that pulls the sheets through the press. The required gripper margin varies by press, sheet size, feeding system, and production setup. It should always be confirmed with the printer.

Work and Turn: A sheetwise layout in which both sides of the job are imposed on the same side of the plate or press form. After the first side is printed, the sheet is turned from side to side while retaining the same gripper edge, and the reverse side is printed. 

Work and Tumble: A layout in which the sheet is flipped from front to back around a horizontal axis before the second side is printed. The opposite edge generally becomes the gripper edge. 

Gutter: The space between adjacent pages, panels, or imposed products. In a bound publication, the gutter can also refer to the inside margin near the spine.

Folding, Binding, and Finishing Terms

Perfect Binding: A binding method in which  gathered pages are prepared and glued together along the spine edge, and then a wrap-around cover is applied. It is commonly used for paperback books, reports, and catalogs.

Saddle Stitching: A binding method in which folded sheets are nested and bound through the center fold with wire staples. This is mostly used in magazines, booklets, and shorter publications.

Scoring: A technique for creating a controlled line on heavy card stock to reduce cracking along the fold.

Die Cutting: A process of cutting with the use of special templates to create custom or complex shapes.

Foil Stamping: A fancy method to get shiny foil, either colored or metallic, stamped onto paper.

Embossing & Debossing: Embossing raises an image above the surface, while debossing presses the image below the surface. The process may use matched dies, depending on the material and finishing method. 

Elevate Your Output With Professional Prepress Printing Services 

Learning the language of prepress and imposition cuts the distance between your digital ideas and the physical product. Now that you know how plates are created, how colors are segmented, and how pages are arranged, your designs will require fewer iterations and will help you avoid costly print jobs. You will get exactly what you imagined.

Stop trusting your important print jobs to chance. An experienced prepress printing services provider can help catch file problems before they result in delays, reprints, or unnecessary production costs.