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The Art of Prepress: How To Take Your Digital Design To Printed Perfection

Translating digital images into printed artwork is truly an artform. A logo or design may look great on a computer screen, but a great deal of work takes place between the vision and the finished packaging.

The smallest adjustments in the prepress and production stages of process printing can make the difference between products that jump off the shelf and those that blend into the background.

Get to market faster by following these tips for product packaging design. Need help? Our experts are here to support you through the process.


Most artwork created for digital use is done in a mode known as RGB, which stands for red, green and blue. Those colors can be combined to produce many other colors of the spectrum.

RGB colors can’t exist without a light source – a computer monitor or TV screen, for example. Human eyes need the light to see true RGB color.

The printing process requires a different mode: CMYK, which stands for cyan, magenta, yellow and black. Instead of reflecting light, CMYK absorbs it. Trying to print a digital art file directly would result in dull, less vibrant colors because of the difference in color modes.

For best results, designers should create their image files in CMYK in InDesign or other design software.

CMYK colors that can be matched exactly in the printing process are referred to as “gamut” colors. Colors that fall “out of gamut” cannot achieve an exact color match during the printing process. If an image requires an exact color match for a brand logo or other purpose, custom Pantone or spot color formulations are used.

Most printing presses have extra decks to accommodate Pantone colors, in addition to those necessary for CMYK inks. Great American Packaging’s new Koenig & Bauer Flexotecnica EVO-XD printing press can accommodate three extra decks for custom Pantone mixtures, plus one for white.

Things to keep in mind:

  • RGB colors are intended for applications that have a light source. Colors for print must be in CMYK mode.
  • Design in CMYK mode, if possible.
  • If you design your artwork in RGB, export it in CMYK mode as a PDF or TIFF file before sending it to us.
  • When printing on a clear substrate (versus paper), white is considered a separate color.


The next step in preparing digital artwork for printing on a poly medium is to understand DPI (dots per inch) or PPI (pixels per inch). They represent the measure of an image’s on-screen resolution. DPI or PPI must be converted to LPI (lines per inch). LPI is the measure of lines in a square inch. Each line consists of a row of halftone dots consisting of small rosettes of cyan, magenta, yellow and black. The variation and size of each rosette creates the simulation of continuous color tone.

Clients should make sure that their files are a minimum of 300 DPI. The resulting LPI on poly bags and packaging media tends to be around 130 to 150 LPI.

Artwork can be created in 300 DPI in Photoshop and similar software, but clients should be careful not to send images directly from the internet. Most websites down-convert image files to 72 DPI or smaller to save on storage space.

Things to keep in mind:

  • DPI files must be converted to LPI before printing.
  • Do not send files directly from the internet –the resolution is too low for printing.


Font choice is important to the printing process. Some font styles and sizes may look great on a video monitor but lose their sharpness and impact when printed. This is especially true on atypical substrates, such as plastic. Great American Packaging recommends:

  • A minimum of 8-point serif fonts and 6-point sans serif fonts for positive prints (dark font on a light background).
  • A minimum of 10-point serif fonts and 8-point sans serif fonts for reverse prints (light font on a dark background).

Serif fonts such as Times New Roman and Garamond use short cross-lines at the ends of each stroke. For this reason, these fonts need to be printed larger to avoid cross-lines running together. Sans serif fonts such as Arial and Helvetica do not contain cross-lines, and, therefore, can be printed in smaller sizes.


During the printing process, ink is applied to the film in halftone dots. Dot gain, also called tonal value increase, is caused when halftone dots expand in area when applied to the printed substrate.

If it is not managed properly, dot gain can cause printed images to look darker than intended or make drop shadows blur and lose definition. In process print, it can also affect the perceived color of the overall image.

The dot gain can depend on many factors including, the structure of the printing plate and the pressure of the plate applied to the substrate. Even the viscosity of the ink can affect the final image.

Things to keep in mind:

  • It is important that only top-quality printing plates are used.
  • Press operators must make the necessary adjustments throughout the printing process to compensate for dot gain.


Production preparation should include gray balance to create a sharper, more impactful image. Gray Balance allows CMYK inks to absorb sufficient light and produce the variation in shades necessary for the final image.

Shadow tightening is a similar process. It concentrates on applying the black ink appropriately where darker shades cannot be achieved through CMY overlays.

Shadow tightening and gray balance can also be formulated to compensate for dot gain. This is especially true where drop shadows have been distorted by the effects of dot gain. Tightening allows the drop shadows to expand to match the dimensions of the original image file.


Consistent registration takes into account even the smallest movement of the printing substrate on the press. Inks and plates must strike a consistent spot on the printing medium so that each impression is located exactly where it should be. Inconsistent registration can lead to unintended blurring or halo effects.

At Great American Packaging, we use only the highest quality, award winning plates to help us achieve the best possible ink laydown. Our plates are designed to match the unique fingerprint of our press, guaranteeing the highest print quality possible.

Finally, color matching can be imperative when it comes to maintaining your brand and logos. Exact color matching is not something that can be accomplished with the naked eye, even by professionals with years of experience. Densitometers are devices that accurately measure the optical density (the degree of darkness or lightness) of each and every color in an original artwork file or sample.

Great American Packaging uses only GRACoL-compliant inks. GRACoL stands for “General Requirements for Applications in Commercial Offset Lithography” and provides an excellent reference source for color printing quality and consistency.


Whether it’s designing your artwork, managing the prepress, or running the press, our experienced professionals have a thorough understanding of the countless factors that come into play when you’re trying to achieve that perfect image on a plastic substrate.

To learn more about these and the many other factors affecting your printed packaging, contact us online or call 877-289-2247 (BUY-BAGS).