What can we do with a Rip driver like Shiraz or Colorbyte?
Or, what are the colour management advantages of using a specialist Rip, like Shiraz or Colorbyte, over a standard driver supplied with a printer?
In short, with Shiraz RIP V6 for example, we have control over the amount of ink being laid down per ink channel and all ink channels together. As a result we are able to avoid over inking on certain types of media and able to reduce the differential of sheen so often seen with the use of pigment inks on certain types of media.
This level of control allows us to find the point at which we can reach the maximum possible colour gamut and density, whilst using the least amount of ink. Over inking will usually lead to a deterioration of colour gamut and no improvement in maximum density achieved.
The first step we take is printing a test strip containing only the CMYK colours.
We measure this strip and then use the measurement data with the Rip software in order to produce a visible graph, making visible the density curves of the printer, ink and paper combination. We now set the maximum level of each channel close to the point where it reaches the maximum density (see below)
Beyond this maximum level per channel (where we reach the maximum density) we see that more ink being laid down on the paper will not increase the density and usually will decrease the colour gamut! We print the CMYK strip again after the maximum levels are set: For example, the black channel is (in this graph) brought down from 100% to 67%. 67% will from now on be the maximum ink level, in other words the new 100% level.
The 2nd printed CMYK chart should be measured and the Rip will make it's calculations to make sure that we get even / equal steps of density from 0% to 100%
The next step is printing a total ink limitation strip. This is used for visual evaluation. It still might be that we get too much ink in the darkest areas where various CMYK channels are laid on top of each other (=total ink). The darkest areas should not show any ink bleeding on Fine art papers and we should see not any wet ink still on top of the surface of Semi Gloss and Gloss papers after it leaves the printer. If we do not pay enough attention here, we will see later a terrible differential of sheen of our prints caused by ink laying on top of the media surface.
We have to print various total ink limitation strips with different settings, until we find the optimum setting. Below 200% is being applied. Once we are finished we need to take the last step: Printing a CMYK target for generating the final CMYK ICC Profile final CMYK ICC Profile
The CMYK test target: ECI2002V CMYK
The measurement from this CMYK target is imported into GretagMacbeth ProfileMaker software and will be compared with the CMYK reference file belonging to the CMYK test chart.
Before we calculate the profile, the software also allows us to adjust the total ink limitation and control the balance between the black channel and the colour channels.
Conclusion:
Maybe it seems all rather easy following the above steps, but finding the exact settings, getting the best possible colour gamut without any over inking, finding the best balance between the black channel and colour channels in order to reduce as much as possible metamerism (meaning an unusual strong shifting of colours under various viewing conditions) without reducing the colour gamut needs you to have gone through this process many, many times.
The trick: Using the best possible hard and software we can find today on the market combined with a lot of experience!
