What is Prepress?

Prepress is the term used in the printing and publishing industries for the processes and procedures that occur between the creation of a print layout and the final printing.
The Pre press procedure includes the manufacture of a printing plate, image carrier or form, ready for mounting on a printing press, as well as the adjustment of images and texts or the creation of a high-quality print file.

Since many publications nowadays are published both in print and electronically, many now refer to the shared processes as ‘premedia services’ instead.

Some special Prepress services include:
Trapping
File Conversions
Electronic proofing
Design
Retouching

 

Lionheart Offset Printing Pre Press Colour Selection Image

Lionheart Offset Printing Pre Press Colour Selection Image

Prepress Overview:

The prepress processes that are listed below may take place at one single location, such as a large publishing and printing company, or at a variety of places.
Usually some tasks happen at a publisher while others take place at a printer or a dedicated prepress company (which are sometimes referred to as service bureaus or trade shops).
Design:
Since the advent of desktop publishing, many people in the printing industry no longer consider design to be a prepress task.
The design process includes:

  • Preparing data, which includes copy editing and product photography, such as for a mail order catalog.
  • Creating the layout is done using one of the leading design application such as Adobe InDesign or QuarkXPress
  • People outside the graphic arts community may use tools like Microsoft Office or Publisher.
  • There is also a wide range of specialized applications for tasks like database publishing.
  • The correction cycle includes processes such as proof reading and image retouching, for which Adobe Photoshop is the leading application.

Preflighting:
Before finished pages go through the remaining processes, a validation is done to check if all the data meets the necessary production requirements.

Proofing:
During the design phase there are already page proofs being created. Proofs are usually also made by the company that is responsible for the printing.
This can be done for internal checks of the impositioning (imposition proofs) –  as well as for their customer who needs to sign off the proofs for approval.
More and more such proofs are ‘soft’ proofs that are evaluated on a computer monitor
‘Hard’copy proofing remains popular when there is sufficient time for it – and for colour critical or expensive jobs.

Imposition: Depending on the final output device, a number of pages will be combined into signatures.
Output to the final output device such as a digital press, filmsetter or CTP device.
To output data, pages or complete flats have to be ripped or rendered.
This process usually also includes:

  • transparency flattening: transparency effects such as drop shadows behind text need to be resolved.
  • color separation
  • color management
  • trapping
  • screening

Some people prefer to delay the above destination specific conversions to the very last moment.
This is commonly referred to as late binding.
Once a job is printed, its data usually go into an archive.

Many of the above steps are nowadays heavily automated, by either stand-alone applications or prepress workflow systems.
The automation also allows for more elaborate communication processes:
Exchanging data such as the final layout may still happen using a physical carrier such as a DVD.
In the past people usually submitted the native data, meaning the original layout file(s) and all associated images, fonts and other data.
Nowadays PDF files are often used instead.

Increasingly the internet is used for submitting jobs
This is referred to as web-to-print.
When the data exchange focuses purely on page content, solutions range from using an FTP server or e-mail system, to using file sharing tools such as DropBox or YouSendIt.
A more sophisticated web portal can add functions such as preflighting and page approval.
A digital storefront enables a printer to not just capture page content, but also order related information.
Such a system can also facilitate reorders and allow print buyers to customize documents on-line.
Job related data such as the job ID or run length are exchanged between systems such as an MIS (Management Information System), a prepress workflow, press control system and finishing equipment.
Protocols such as JDF allow systems from different vendors to exchange the necessary data.

Many projects nowadays are published using other media besides print as well.
The content of a magazine may also be published on the web while the content of a book is re-purposed for e-books .
There are special tools and protocols such as XML to facilitate cross media publishing.

Trap on a press is the ability of a printed ink to accept the next printed ink, compared to how well paper accepts that ink
Registration is when all printed images are lined up over one another.

What does Trapping in printing do?

Trapping is a term originally used as a measure of how well one ink printed on top of another.
Trapping involves creating overlaps (spreads) or underlaps (chokes) of objects during the print production process to eliminate misregistration on the press.
With the advent of Pre-press Software the term was misused to describe the compensation for misregistration between printing units on a multicolour press that was traditionally known as “Chokes and Spreads”.
This misregistration causes unsightly gaps or white-space on the final printed work.

One approach to trapping is to change the submitted artwork
In general, all digital files produced using any current professional software have some level of trapping provided already, via application default values.
Additional trapping may also be necessary, but all traps should be as unobtrusive as possible.

Traps can be applied at several stages in the digital workflow, using one of two trapping technologies: vector-based and raster-based. The right choice will depend on the type of products (packaging applications including flexo-printing have other requirements than commercial printing on offset systems) and the degree of interactivity or automation that is wanted.

In-RIP trapping moves the trapping to the RIP, so that it is done at the last moment.
The process is automatic, although it is possible to set up zones to allow different automatic rules for different areas, or to disable trapping for areas previously manually trapped.

File conversions:
Many people do not understand that some file formats do not print well.
For example, images in jpgs need to be converted to a png or TIFF format for better quality printing,
Please read our “ Print Ready Artwork Specifications” for more assistance.

Electronic proofing:
Electronic proofs are digital versions of your project that can sent to you online.
Lionheart has 2 versions jpeg and PDF.
Note: whilst these proofs are fast and easy to deliver and show the layout of any project, as a digital proof, the colour reproduction is not always accurate.