We are in the process of refining our ability to profile our large format digital printers in house using the latest version of i1 profiler with a i1 (UV filter attached) to help correct for our optically brightened substrates.
We believe the most recent profile we have build is very linear and produces pleasing color (perceptual intent) for photographic work. However a lot of what do print requires the best possible match to PMS spot colors. We have found that if we use the color replace function in our RIP that we are able to achieve color matches that our profile says are out of gamut.
My questions is if we are able to produce a color mix using the same inks on the same printer & substrate that produce a good spot color match via the same printer CMYK print how can these colors be considered out of the icc v2 profile gamut we built with i1 profiler:?: Should we be looking at using a different rendering intent, a different way of building blacks. Have we done something that has limited the gamut of our profile or is it that yes we can achieve these color but they are out of gamut because their inclusion would cause spikes the profile that are corrected for in the processes as they would not be linear:?:
Technically speaking, if the colors are truly out of gamut, then you would not be able to print them.
It would be good if you could give us more information about what is telling you that the colors are out of gamut. Are you going by the gamut warning in Photoshop, or is this some feature of your RIP (which one), or are you using a gamut viewer like ColorThink?
If you’re looking to get good color matches with saturated colors, its generally recommended to use relative colorimetric for printing. That will give you more saturation than perceptual.
As we discovered in this Tips and Tricks video, it is possible for a profile to not give you all the saturation a printer is capable of - but a good profiling engine like i1Profiler should get you almost everything that is printable.
It sounds like you might be using Onyx. What I have found that works is that I always build a custom media model and ICC profile from scratch. When I evaluate spot color matching, I will send one of of the test files in the Onyx Samples folder. This file has all of the PANTONE Coated and Uncoated values. We print this to the profiled media model using the “Use Spot Color Matching” feature, which I understand is a direct PANTONE to LAB - LAB to CMYK rendering using RelCol where if a color is out of gamut, it gets mapped to the closest available hue. However, if the visual match is not right, we have clients visually pick the closest PANTONE based on the printed chart.
It’s also important for files to have PANTONE colors set as Spot and not process CMYK. Designers make this mistake all the time.
