According to the poll, colour accuracy is what most of us are concerned with when it comes to printouts. Indeed, perfect colour accuracy depends on many factors and that’s why it’s one of the biggest printing issues. But let’s start with the basics. How can we tell if colours are accurate? By checking on the computer screen? Through a hard proof? And under what lighting conditions?
First of all, it is certain that the computer screen cannot be an absolutely reliable consultant. We need to understand that screen colours are lit from the inside, while colours on paper are lit from the outside. The screen works with RGB (photometry), while printed paper with CMYK (inks). However, our screen output can be close to the printing output if it is properly calibrated. To calibrate the screen we can use a device like eye-one of greta macbeth or colour munki of x-rite, and fix the display level of the screen.
eye-one of greta Macbeth
colour munki of x-rite
Properly calibrating the screen is the first thing we have to do. Since calibrating devices are costly, you can find companies providing this service, but you have to know that this procedure has to be repeated regularly (at least every six months).
The second thing we have to do is get a certified hard proof. As I have mentioned in previous posts, it’s best to work based on the ISO standards. For a hard proof to be certified based on the ISO standards, it has to carry a colour bar, which can be measured and verified with a special device (like eye-one). Its verification can be confirmed by the label with the signature of the person responsible.
GMG hard proof certification label
However, even if we do these two things, there’s one more factor that most of us seem to ignore: the lighting under which we look at the proof. All printouts develop the effect of metamerism. This means that the colours change depending on the light under which you look at them. The right lighting for proofs is 5000 Kelvin produced by special lamps. However the cost of these lamps is very high and they are not used anywhere. So the result we see on the proof under our lighting is completely subjective. Of course, the people who’ll see the final product will also use simple lighting. So we must be aware that the colours will present small variations depending on the lighting under which we look at them. The variations will not be too obvious, but for some colours they will be apparent.
A week ago we had to deal with this issue with one of our clients. On his screen he saw warm red colours and on the hard proof they were relatively cold. The difference was not too big but his products were linen with pale colours and he wanted the output to be exactly what he saw on the computer screen. He was looking at the hard proof under common white lighting and the colours were different, however, when he saw them at our printing house under the proper lighting, they looked exactly like they did on screen.
That’s all about colour variations…
If we want to protect our projects we have to calibrate our screens and get colour-certified hard proofs. Based on these two features, the offset printer can give out a better printout and we can expect the output to be exactly as we wanted it to be.