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UNDERSTANDING DIGITAL PRINTING
Digital printing is used to allow for the greatest flexibility of design with thousands of colours to add depth to all our patterns. New patterns and print media are added on a regular basis.
Industrial Digital printing works basically the same way that a desktop ink jet printer works but at a greater scale. Variables at the printing level include the inks/pigments/dyes used, the substrate printed on, and the speed and dpi printed. This short guide will walk you through the basics of visible colour, how the eye works, colour gamut, platform to platform variance, substrate variance, lot differences, and lighting standards.
VISIBLE COLOUR
The human eye perceives but a very small wavelength of the entire electromagnetic spectrum. Some people perceive a greater range than others and some animals can see into ranges that are not perceptible to the human eye (Bees, for example, can see into the Infrared). The most dramatic example with people is colour blindness. Inside the human eye are Rods that perceive grey tones only and three types of cones that perceive different primary colours (Red, Green and Blue). People who are colour blind have defective cones of one type or another.
Notice the rods in the eye are Red, Green and Blue. These are the primary colours of what is known as Additive colour. Pure wavelengths of visible light work with Additive colour such as from televisions, computer screens, colour gels used in theatre sets, etc. All three primary colours together create white light. Subtractive colour is light reflected from a surface or object. In subtractive colour the primaries are Magenta, Yellow and Cyan. All three primary colours in this system create black.
Digital printing, screen printing, dyed textiles, and paintings all use Subtractive Colour. Depending on the machine (and supplier), in question Mushaboom Design prints are created using tiny dots of Magenta, Yellow, Cyan and Black next to each other (some machines have additional pigments to create a broader gamut). They blend together optically to create thousands of possible colours but there are definite limitations. Not all colours can be matched and some colours that can be matched when printed on some substrates cannot be matched on other substrates.
Here you can see the continuous tone effect of a print as viewed by the eye from several inches away but as you get closer you can see the dots. This is not a flaw, just a natural characteristic of the technique. Only in extreme cases, when a colour cannot be matched is it considered a flaw and then the colour area will look quite speckled even from a distance.
The diagram below shows some examples of variance between what the human eye sees (the horseshoe shaped area), and what some technologies can reproduce. It illustrates that sometimes, a colour you can see cannot be matched due to physical limits of the technology, pigments or dyes available, and substrates used.
LIGHTING
The next important thing to understand is that lighting types and conditions can change how colours are perceived. Look back to the diagram of the visible spectrum, it is conceptualized based on the idea of ‘pure white light’. However, in reality we never encounter ‘pure white light’. Even natural sunlight at noon has more green and yellow in it and less red and magenta as seen in the diagram below. This phenomena is referred to as the colour temperature.
Notice how the light of Noon Sunlight, while it certainly has the flattest profile still spikes in some parts of the spectrum. This chart compares it to other light sources; Tungsten (incandescent), lamps, white LED (similar to fluorescent), and Mercury Vapor Lamps (usually found in stadiums and large trade show halls). If you had a paint chip and looked at it under these various lighting conditions, it would look different under all of them.
Colours which may seem perfectly matched to each other under one light source may not match at all under another light source. This is known as metamerism and is the reason why knowing the final lighting conditions is important and why we set standard lighting conditions for matching colours (Daylight, Kelvin 5000, D50 bulb).
PRINTER TO PRINTER (PLATFORM), VARIANCE
Not all printers are the same. Some printers have more base colours to work with than others meaning they can print a larger range or gamut. The gamut can also vary simply based on the colourants available but also by the software used to match colours. This is known as platform to platform variance. You can test this simply by printing something on your printer at home and then take the same file and print it on another printer. They will certainly be different. Mushaboom Design may, as needed, supply you with colour prints for approval but only a Production Proof, which is printed on the production printer on the chosen substrate, can be used for final approval. SUBSTRATE (MEDIA), VARIANCE
Each material on which we print has itʼs own unique characteristics of base colour, texture, which
LOT VARIANCE
Like most manufacturing methods, there is definitely colour variance when comparing one lot to SUMMATION
Having a basic grounding in the technology of digital printing so that you understand the |
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