February 28, 2023

Reviewing Color in Press Proofs

So, you created and submitted a print-ready art file, and then received a proof approval email for your latest graphics project. Now what? Before you click the green “Approve” button to send your file into production, you need to carefully review the proof for spelling errors, design content, technical colors (cutlines, creases, v-cut, white ink, and gloss), final print size, and production quantity. Electronic proofs are provided for all files and will indicate the design intent, but the rendered electronic images should not be used for ensuring and approving color matching. If requested, we can provide hard copy press proofs for color approval at an additional cost. This blog post will outline how to review colors in hard copy press proofs.

FACTORS THAT AFFECT THE APPEARANCE OF COLORS

Lighting

Industry best practices for color matching suggest that it be done in a viewing light booth that simulates direct sunlight (or other light source). Indoor light produces a very different color presentation than outdoor lighting. If your graphic will ultimately be installed internally, factors such as the color temperature of the lightbulbs, how many sources of lighting there are in the room, etc., can dramatically change the look of a printed graphic. The human eye is used to seeing things with outdoor lighting conditions which measure about 5000 Kelvin (K). Viewing under fluorescent lighting, about 4000K, can cause a greenish tint, whereas viewing under incandescent bulbs, 2700K, will cause a yellowish tint. High-intensity halogen bulbs and variable LED bulbs emit more different color. Additional factors need to be taken into consideration for outdoor graphics: building shadows, direct or indirect exposure to the sun path, and any artificial lighting can all affect the color appearance.

Material 

Not all materials share the same white point – some are bright, slightly yellow, or have a grey tone. Some don’t even start off white! All of our high-end large-format printers print directly on specialty substrates like acrylic, wood, cork, painted materials, and other custom materials that all have different initial colors. Some substrates absorb ink. On others, the ink sits on the surface or is only partially absorbed.

COLOR MATCHING ACROSS DIFFERENT SUBSTRATES

Our experienced prepress operators are experts in color correction and color matching. Additionally, modern software can very closely replicate a required color using input from a photo spectrometer. The combination of skill and technology is usually adequate. However, for difficult colors or varieties of materials, it may be necessary to provide a “ring around” (pictured right) which will encircle the best match with slightly different but still very close color options from which to choose.
Note: There are times where, due to the nature of the printing process, some colors cannot be exactly replicated. This is especially common for bright neon, pastel, and metallic colors.

Incorporating Paint

For commercial interior décor and retail displays, clients often want brand colors to span both printed graphics and painted accent areas. Whenever possible, it is best to start with the printed color and then match the paint to the printed graphic. It is generally much easier to make slight adjustments to paint color because it has more volume and a wider range of pigments.

Fabric

Fabrics depend on the type of material to be sublimated. Front lit fabrics are viewed much the same way as other printed substrates, in a light controlled room. Colors on back lit fabrics must be adjusted by the processing software to compensate for the light being filtered somewhat by the fabric. If you are using previously installed lighting for these graphics, remember that color temperature of the lights makes a difference in the viewing color.

Gradients and Transparencies

Graphics that incorporate gradients and transparencies can produce results that look different than on a digital proof. Critical effects might be best viewed on a sample printed on the actual material.

KEY TAKEAWAYS AND FINAL THOUGHTS

When reviewing press proofs for color accuracy, there are a few general guidelines to keep in mind:
  • Proofs should ideally be viewed in a color corrected light viewing booth. This is the only place where we can precisely match color. If you would like to view your proof in our light booth yourself, please speak with your Infinity Images project manager to arrange a meeting.
  • Color critical graphics may require several iterations to produce the desired effects and incur an added fee.
  • The final delivery of the graphic should be considered when reviewing the proof. For example, a billboard proof should be viewed from at least 20 feet away, while a retail display signage proof should be viewed from 2-5 feet away, depending on its location in the store.

What Does Large-Format Printing Mean?

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