In my recent blog I explained why the demand for printed fabrics is increasing and the challenge this poses for the digital print industry. Today, with help from Digital Imaging Expert Scott Martin of Onsight, I will share tips and tools to help printers profile textiles for a consistent digital workflow.
While smooth textures can often be measured using traditional digital tools, fabrics with texture or specular reflections (like coated canvases) can cause issues. It's a lot harder to achieve consistency on a coarse weave than a smooth weave. Fluorescence further complicates things because you probably want to capture and characterize the color of fluorescent ink, but if the fluorescence is in the fabric you will likely want to cut it out.
When digitally printing textiles, it is crucial to linearize and profile each substrate to achieve the highest level of color accuracy. Today I'll explain why traditional profiling devices are not well suited for the job and offer tips accurately profile textiles.
Close up of a profiling target on glossy canvas. Image courtesy of Scott Martin Onsight.
New Materials Require New Tools
To print accurate color on textiles, print shops need to reconsider their color measurement devices.
Traditionally, printers use a 0:45 or 45:0 spectrophotometer for a digital workflow because it's the standard for graphic arts and best mimics what the eye sees. Although this type of device works well on even surfaces, the smaller aperture cannot capture enough of the sample for an accurate reading or properly handle gloss.
A sphere spectrophotometer with a large aperture and very indirect lighting can be used to help “smooth out” the readings of highly textured fabrics, but is not optimized for most digital workflows. To properly profile textures, digital printers need to consider two things.
1. Aperture Size
A 2 mm aperture is common for graphic arts because it can measure small color bars. Digital print may go to 4 or 4.5 mm to capture a little of the variability in early digital print materials. However, as you can see in this graphic, not even a 4 mm aperture is large enough to capture enough of the variability in a textured weave.
With an 8 mm aperture, the i1Pro 3 Plus can capture 28x more area than a 1.5mm aperture, reducing variability on textured and fabrics for more consistent profiles. It also offers virtual scan, which captures multiple locations to further reduce variations in the material affecting the results.
2. Polarization
Polarization can be an issue on surfaces like canvas that start to lose color because gloss and specular highlights can veil dark colors. As an example, here is the 3D gamut for a glossy canvas fabric swatch measured by Scott Martin using an i1iSis 2 with its small aperture optimized for paper.
Image courtesy of Scott Martin, Onsight.
When you measure a fabric like this using a small aperture without polarization, you can encounter problems because specular highlights will cause you to miss data down in the dark area, resulting in a little bit of roughness in the shadows and reduced overall gamut.
Image courtesy of Scott Martin, Onsight.
This is a 3D gamut of the same swatch, measured using the i1Pro 3 Plus with an 8 mm aperture and polarization. It looks much bigger and smoother because the large 8 mm aperture allows a lot of light into the instrument to get the best measurement, while also reducing the effect of micro-highlights.
Image courtesy of Scott Martin, Onsight.
We don't see those micro-highlights with our eyes. We see the actual color, which is exactly what we're trying to cure with polarization.
Many color scientists wonder whether polarization changes the color because we've lost our white point. The fact is we didn't lose our white point because our “paper” is still the paper and the white point is still there. What we've done is filled out the bottom of the gamut area and cleaned up the saturated colors and those darks because they no longer have micro-highlights.
Of course, polarization isn't a cure all for everything, but it's a great tool for your toolbox, just like polarized glasses to avoid reflections in the real world.
Choose the Right Spectrophotometer for the Job
The i1Pro 3 Plus was designed to calibrate and profile a variety of textile substrates, including organic, synthetic, weaves, and sublimation sheets. With the ability to measure a larger area and polarize, it can reduce color variability on less traditional fabric-type surfaces. It can even eliminate chromatic highlights for better profiles that translate to fast production with less wasted time and materials.
Best Practices for Profiling Digital Textiles
To ensure you get the best measurement results on textiles:
- Use a wide-measuring aperture to allow as much light as possible to enter the device. The 8 mm aperture on the i1Pro 3 Plus is ideal.
- Firmly anchor the material. Although this can be tough with fabrics, it must be dimensionally-stable. The i1Pro 3 Plus comes with magnetic bars that work with an included backer board to ensure the fabric is dimensionally-stable.
- Take multiple measurements per patch. The virtual aperture feature on i1Pro 3 Plus does this for you, making it a real advantage of the i1 series.
- Choose the right measurement mode:
- Use M1 to capture fluorescent effects. In the proofing world for graphic arts, we've largely moved to M1 to capture the effect of OBA fluorescence. It can also capture the fluorescent effects in fabric.
- Use M2 to eliminate fluorescent effects. In fabrics, it is helpful to cut the fluorescent illuminant back when you're not concerned about a proofing paper to other substrate match, just getting the right color on the final material.
- Use M3 with polarization to eliminate both the fluorescence and the specular reflectance. The polarizer is automatically a UV filter, too.
Profile Like a Pro
It is possible for digital printers to get an amazing quality result for traditional ICC profiling on less traditional fabric-type surfaces. Get in touch, read Scott Martin's i1Pro 3 Plus review, or visit our website to learn more about the i1 Pro 3 Plus Family.
