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Large format file preparation guide

*Goals and Design*

When preparing your files for output, you need to determine the goals of the project and then choose a medium and create a design that will best meet your goals.

For example, if you are a Marketing Manager given the task of producing a giant banner for a product launch, you need to make sure your design will translate well when printed very large and viewed from a distance. If you’re preparing for a trade show, you need to consider both distance and the fact that people will be darting by your booth, requiring your visual content be potent enough to catch wandering eyes.

The best solution when designing for large-format printing is to keep it simple and direct. Subtlety and complexity are difficult if not impossible to see at a distance and when competing for viewers’ attention.

The bottom line is to create a message that the medium can support.

*File Preparation Tips*

When blowing up images to large sizes from computer-generated image files, it is important to make sure the files were created in formats and resolutions that will assure quality results when printed.

There are three main issues to be aware of and if you’re careful, you’ll be amazed when you unfurl your product from the carton.

# *Resolution and File Formats*
Resolution relates to how crisp your images will appear when scaled up to many times the size you’re viewing it at on your monitor (72 dpi) or the color laser hardcopy proof you printed to get design approval from your boss or client (300 dpi at 8.5” x 11” size).

DPI stands for dots per inch, which harkens back to the world of offset printing where printed images are literally composed of CMYK dots that combine to form the illusion of a solid image on paper. Although computer images are defined by combinations of RGB pixels (rectangles instead of dots), the term DPI has carried over and is usually used to determine how many pixels are actually present in a computer image at any given size (e.g. 150 DPI at 30” x 40”).

Most large-format output devices are now capable of yielding output at resolutions of 300 DPI or higher at giant sizes, yielding very clear crisp results (have you seen billboards lately? Or been stuck in traffic next to a bus that is wrapped with adhesive vinyl panels advertising the incredibly sharp facial features of your favorite TV personalities?)

The formula for getting it right when going “grand” is actually pretty simple as long as you prepare your files properly in advance.

The good news is that there are certain file formats that don’t depend upon resolution to look great any size. These are called vector files.

Fonts and .eps logos are classic example of vector file formats.

Vector graphics can be stretched like rubber bands or blown up like blimps and they will still look sharp. That is because vector files, unlike their needy counterparts, bitmap files (which we will get to shortly), are defined by mathematical ratios, not a finite pre-determined number of pixels.

When preparing documents for large-format output, bitmap images require the most attention. If you create images in Photoshop, scan photos, or take photos with a digital camera, then you need to make sure those images possess enough resolution (DPI) to print properly at their final size. If you don’t, your poster or banner could look like some kind of horrible disaster at Lego Land!

For example, if you’re designing for a final size of 36” x 48” and you want to get your images to 300 DPI at that size, you can set your page up for 18” x 24” (25% scale) and import your bitmapped images at 1200 DPI and they will then blow up nicely to 300 DPI when scaled up 400% to 36” x 48”.

Note: Your intuition might tell you that 25% size of 36” x 48” is equal to 9” x 12”, when in actuality, 9” x 12” is equivalent to 1/8 the size of 36” x 48”. Your intuition wasn’t paying attention in math class, as scaling up is an exponential process! Okay, just look at the handy chart below and it will help you catch up on your geometry.

Designing at 25% of your final output size is a good way to help manage your file sizes, because bitmaps at full-resolution, full-size can be very cumbersome to work with.

By the way, for most poster and banner applications that are not especially complex, detailed, or subtle, 150 DPI at 100% will yield pretty good results. On the other hand, if you’re dealing with detailed and/or color critical imagery, 300 DPI at full-size is a better choice. If you’re designing something color critical at 25% size, you need to make sure your bitmap imports or Photoshop document are at 1,200 DPI.

When you’re dealing with REALLY BIG stuff, you can often get away with 150 DPI at full-size, simply because your final output will probably be viewed from a greater distance (“good from far, far from good”). In other words, it doesn’t matter if it looks a little grainy or jagged up-close, because your audience will be at a safe distance from the display (e.g. an arena or large event setting).

# *Color Management*
The two main color models utilized in computer graphics are RGB (Red, Green & Blue) and CMYK (Cyan, Yellow, Magenta & Black). How your final output is printed or viewed determines the correct color system to choose when preparing your files.

If you’re designing for digital or offset printing, or for that matter, any ink or toner-based printing device, you should be designing and proofing your images using CMYK. If you’re designing for a monitor screen or projector-based presentation, 35mm slide imaging, or a Digital C Print, you should work in RGB, as that is the native color model for those environments.

Note: Digital cameras produce images that are RGB, which is why they look accurate on your monitor (also RGB). If you’re taking digital camera images and putting them into a CMYK design, make sure you bring them into Photoshop (or any other image processing software) and convert them to CMYK first. That is also a good time to check the resolution (DPI) of those bitmapped images to make sure that they will look good when printed large.

# *Submitting Files for Printing*
PrintPromotion.com supports native documents from most major graphics software packages (e.g. Illustrator, Photoshop, Quark, InDesign, Powerpoint). If you’re not sure about a file format, please feel free to call and ask.

We also support exported files, such as .tiff, .eps, or high-resolution .jpg and .pdf files (again, feel free to call and ask).

If you’re using native file formats, make sure that you include any imports or fonts that are not imbedded in the files (e.g. use the “collect for output” command in Quark that automatically gathers up all of the support documents and fonts your file requires for it to output correctly).

When you’ve gathered everything together in one folder, compress the files into archives using stuff-it or .zip so that all the files are batched into one file that is significantly smaller in megabytes than the raw files would be. Smaller files upload faster and are easier to store and manage on both ends.

Thanks for trying Printing Responsibly and we hope this quick little lesson in the basics has been helpful.

Filed under: File Preparation on June 11th, 2005