You are in:
Colour management in wide format and flatbed printing
Corporate identity and colour play a fundamental role in visual communication. This can only be guaranteed with colour management as Durst explains
Every printer knows that printed colours are not always identical, nor do they always match the original shown on the monitor. Why? Temperature, humidity and atmospheric pressure all influence colour appearance to varying degrees. Different methods of image capture (digital camera, scanner, etc), correction software and display equipment are even more critical factors.
Factors that particularly affect wide format and flatbed printing are the RIP software, ink and media used. The RIP influences the colours as it is responsible for printer linearization, how the dots are printed, the amount of overprinting, etc. Different ink types (UV, dye, water, solvent, etc) have different colour appearances. Media is the most critical component, with new ones appearing almost daily: each with different characteristics. The media’s white point influences colour appearance. For example, an image printed on cardboard will not be the same as one printed on paper, glass or textile. Trapping is also important. If a media absorbs lots of ink, the printed colour will be different from one printed on a less absorbent media. This has a particular effect on colour saturation. Also, the media surface must be considered.
Operators also affect finished products. They often modify colours to match originals but different strengths and weaknesses of the human eye mean not everyone sees colour in the same way. Furthermore, there are preferential differences between people of different countries.
To date, most laboratories provide customers with sample prints, adjust the colours and print again. This repeats until a satisfactory result is achieved. Obviously, this process wastes media, ink, time and money.
Many media and printer suppliers assist customers by delivering generic profiles. This is good but only represents a fraction of the task. Generic profiles describe the printer/ink/media/environment when the profile was created. The exact same situation seldom occurs at customer’s premises. Thus, colour management and individual profiles are almost a must.
For the printer, this means creating a profile for every printer condition (dpi, speed etc) with combinations for media used. Once complete, the operator has the following benefits:
- Guaranteed colour true prints
- No wasted time, media and ink
- Perfect spot colour matching
- Reprints a perfect match to the first print
- Simulation of printed colours on the monitor
- Exploitation of the whole colour space
- New media can be used immediately after set up
Spectrophotometers are used for the following:
- Linearization: this guarantees the correct percentage and distribution of ink on the media and ensures no clipping occurs
- Profiling: captures the colour gamut boundaries and allows calculation of visually perfect grey values and description of printable colours
Choice of measuring device is important. Versatility is critical. To build the most comprehensive profile the largest possible number of combinations must be read. To do so quickly, avoiding mistakes, requires an automatic measuring device. In wide format and flatbed printing, both high and low resolution are required and the measuring device must be able to handle this.
The greatest challenge for a measuring device is different media. The device must be able to measure anything: paper, wood or even ceramic tiles. Furthermore, every media has a different surface. To measure them, different measuring apertures are needed. A smaller aperture is required to measure paper with its smooth surface, a larger aperture to measure textile with its structured surface.
Some inks are sticky so the measuring head must not touch the surface during measurement. Inkjet printing on transparent media has become popular and also requires colour management.
To ensure colour management over the whole production process workflow, a complete and aligned printer/RIP/measuring device solution is required. RIPs already exist that drive printers and the measuring device, guiding the operator step-by-step through the workflow. In particular, they are responsible for linearization and profile creation, handling and applying the created profiles automatically making colour management easy.
Printers that apply colour management across their entire workflow will gain a significant competitive edge. It offers the opportunity to accurately meet a customer’s requirements while providing a faster and more cost efficient service.
