| |
Preflight of Electronic Files
Prior to Final Output
Technical Guidelines
Preflight of electronic files: A methodical procedure established to ensure that files will output as intended on schedule with no re-runs. The following steps are recommended to find potential problems ("electronic hairballs") before the job is queued for output and early enough in the production cycle to obtain missing pieces or make changes.
Preflight is handled in two stages: job setup (or sample pages) and live prepress production. The preflight check during live prepress production is virtually the same as for sample pages.
Color palette, grid, and sample pages or client-supplied test files are carried through to film and checked for the following:
- The color palette is checked for accuracy of color and includes a densitometer check of tints. A Matchprint is made of film and checked before routing to the client for approval. Once approval is given, colors can be used to build masters for production. Proofs of color palettes should be generated in every medium in which the client will see color: Canon Fiery, Iris, Doublecheck (Ekta), and/or Matchprint, as appropriate.
- The grid is output to film positives and spec-checked for trim, bleed, type area, and backup of verso and recto pages to ensure mirroring of margins and print areas. Film positives are routed to the client for approval prior to setup of master page templates.
- Sample pages or client-supplied test files are first approved by the client as Fiery color laser proofs. Before film is run, color-separated laser proofs are run and checked against the Fieries for the following:
- presence of all fonts in both text and art. Verify that special characters such as accents or math symbols are not missing
- separation of all process colors in devices and object-oriented (vector) art
- knockouts and overprints in art and screened text areas
- Color laser proofs indicate what colors, tints, etc., have been used. Because they are only 300-dpi proofs, they do not always adequately display type density, rule weights, or trapping. Therefore, carefully review sample page film proofs for design approval of type attributes.
- Color-separated laser proofs are black-and-white proofs of what will appear on each plate when film is output. These proofs should be output by the vendor who runs the final film. When separated laser proofs are generated, the low-res .apr files are swapped for their high-res counterparts just as when film is output.
- presence of all icons
- clean edges on art and photos
- fit of images in windows and trapping of rules
- bitmapping of scanned (raster) art and photos (indicates that high-res image did not swap)
- bleeds and crossovers per spec
- banding problems on gradient screens
- incorrect stroking of type (signifies a layering problem in Quark, usually where type thinks it needs to trap to a white background because some part of the text box is touching an art box)
- possible design problems affecting print viability
Planning for Web Presses
Here is an excerpt from our seminar on electronic publishing: "After all is said and done, however, the rule still applies: Just because you can do something doesn't mean you should!" The final design must hold on press. Assume a press gain of at least 10-15% for high-speed web presses.
Therefore, avoid the following:
- specifying 2-screen mixes of type smaller than 14 points, rules thinner than 2 points, 3-screen mixes of any type, or thin rules
- specifying colors in the palette in less than whole number increments (e.g., 10.5% cyan) or colors that contain less than 5% of any one color
- reversing type designed with thin ascenders/descenders or fine serifs
- gradients with insufficient screen range
- butting colors that do not contain common colors (e.g., 20% yellow/20% magenta butting to 20% cyan/20% black). To avoid trapping issues, use complementary colors: lighter/darker versions of the same color or a common color (e.g., 20% yellow/20% magenta butting to 20% magenta/20% cyan).
Running Sample Film
Film is run, and internal Doublecheck proofs are made. The proofs undergo another quality control check for registration, knockouts, and trapping. Matchprints are then made and also checked for quality before being sent to the client for final approval. Once the samples/test files are approved, full production can begin.
Live Prepress Production
The steps for live prepress production are essentially the same. If standing devices and problematic design elements are addressed (and corrected as necessary) during the sample process, it is rare that problems arise in these areas during live production. Of course, in our industry, Murphy was an optimist. Therefore, for the sake of budget and schedule (and sanity), any design changes that occur after samples have been approved should go through all the same quality control steps as original sample pages/test files.
Once live production commences, the preflight begins with an online check of the electronic files before separated lasers are run. With client-supplied files, we look for (and unfortunately quite often find) these problems:
- incomplete file folders: the folder does not contain all related art files, .apr files, TIFF files, etc. This is the most common problem with supplied files and causes inordinate delays
- improper file format use
- missing fonts in text and art (incomplete suitcase provided)
- process colors not turned on
- incompatible versions of software
- incorrect version of the file (does not match hard copy submitted with disk and printout of directory)
Finding and correcting these problems online minimizes what is found in the check of separated lasers.
Note:
The charge for preflight of client-supplied files includes online analysis, generation of color-separated proofs, and the actual "eyes-on" checking process. It does not include the cost of actually repairing the files to be output-viable.
During live prepress preflight, attention is focused especially on the variable parts of files: art, screened areas, icons, separations, etc. Before outputting imposed film, sample flats are sent to the designated printer for approval of setup of the imposed pages and printer marks. Special considerations apply to el-hi teacher wrap editions with reduced imported student pages or ancillary pages:
- Does the ratio of reduction of the SE or ancillary properly fit the window in the TE?
- Have type or images changed position in the reduced version as compared to the 100% version?
- Are annos appearing in reduced SE's and ancillaries?
- Do folios in source documents change when imported into target documents?
|
|
