PREFLIGHTING

Preflighting is the process of checking digital files prior to film output. It can be done manually or with the assistance of a software package. The purpose of preflighing is to identify problems that may occur in the print process prior to outputting film, therefore reducing or avoiding the risk of wasting money by catching errors when they are still easy to correct; prior to film output.
Font problems are the most common problem encountered with digital files. Missing fonts and unstable font formats are the leading gremlins that can crash your well planned project. Always remember to send both screen and printer fonts along with your files. Screen fonts are those which appear on the monitor.Printer fonts are the fonts that are actually utilized to create text in the final print product.

TrueType Fonts tend to be problematic due to the fact that there are no screen and printer fonts as in Type 1 fonts. Instead, there is only one scaleable font which, while OK on the monitor and when output by a laser printer, tend to be problematic when outputting through an imagesetter.

Improper Font styling is a common problem. Type 1 fonts are created with a separate font for each style, that is, plain, bold face,italic, etc. In page layout programs such as Quark and Pagemaker, styling can be applied to any text much like a word processing program. While this may look OK on your screen and even print nicely on your laser printer when the file gets to the image setter it will undoubtedly cause problems.

Imagesetters need the actual font, ie, Times Roman Italic, Times Roman Bold, etc. so be sure to include all typefaces that have been utilized in your document.

Unused Fonts are a problem when they are called for in a style sheet or template but are not actually used in the final page layout. If a font is identified in the style sheet, the imagesetter is going to look for that font regardless if it has been used or not.

Image Problems

Before we can have a meaningful discussion about Image Problems, we will need to define a few technical terms, so read on.
Image files can be divided into two main categories; Low Resolution or High Resolution. A low-resolution file is defined as less than 300 ppi (pixels per inch). They're usually used as RGB GIFs and JPEG's for web use at 72 ppi. A high-resolution file is defined as 300 ppi or higher, and in CMYK mode for printing. They're usually used as TIFFs and EPS files, and sometimes CTs.

A typical problem occurs when only a low resolution file is provided. When output, it will look jagged, blurred, lacking in definition, or as we in the industry technically call it, "really ugly". Therefore, always check to make sure the high resolution files, not the low, are included. If you use OPI, then we will have the high resolution files on hand here, and will "swap out" automatically to high resolution.

Another popular glitch is not linking image files properly if they get renamed. Example: Your designer is rushing to meet a deadline. He/she makes a last minute change to a graphic filed called "Logo-1" resaves it as "Logo-2" and then wisely removes the old logo file from the disk. When we attempt to output the file, the imagesetter stops and gives us a look not unlike the RCA dog with his head tilted to one side. Why? Because the page layout still calls for "Logo-1" which no longer exists. Things could be worse... what would have happened if the designer had NOT removed the old logo? Your proofs would have arrived with the old image in place and if the error wasn't caught, your finished piece would have gone to press with it.

The failure to specify the proper amount of colors for a given job happens quite often. If you have ever gone through the experience of noticing that type or other elements are missing from your proofs, quite often the reason is the improper specification of color. As an example, if a job is specified to run as two colors only, with PMS 200 and PMS 135, but there are elements in the file that are specified as PMS 201, these elements will not appear on your films. The reason is that your printer has instructed its computer to output only 200 and 135. If 201 has not been specified, it will not appear in the final output.

Why colors don't print the way you last saw them on your monitor.

ADDITIVE PRIMARY COLORS The red, green, and blue (RGB) components of light are called additive primaries. The display of all monitors is RGB. The additive colors are transmitted from light sources through the monitor.
SUBTRACTIVE PRIMARY COLOR A color system in which pigments, cyan, magenta and yellow of printing inks, are mixed to form other colors. Subtractive colors are created by light being reflected rather than emitted. Because of the difference between the way additive and subtractive colors are seen, color variations will be experienced when viewing colors from different light sources.
RBG COLORS vs CMYK COLORS All computer monitors create color via RGB components. The RGB mode has many millions MORE colors than the CMYK spectrum. Too bad we can't print RGB!!

Dot gain

It's not a woman's name, it’s when your colors darken on press.
The printing process is centered around color and contrast being created by dots. As the perfectly formed dot comes in contact with paper it tends to spread, more or less based on the absorption of the paper. Because of this, colors on the printed sheet will often appear darker than on your computer's monitor in your office. This is known as "dot gain".

Trapping. The overlapping of one color over another.

A computer gives the user the ability to perfectly align colors. Since the printing process is an imperfect one, the same accuracy cannot be expected when the job is running on press. Therefore, when two or more colors touch eachother, a process called "trapping" is utilized. Trapping entails having different colors overprint eachother slightly, in order to compensate for any shifting of the paper as it goes through the press. The "trap" can be applied by the designer but it is usually advisable to allow your printer to apply traps because the amount of trap required will vary according to the press on which it is being printed, the sheet of paper being used, ink color, and position on the sheet of paper.