M1: Million Reasons
Using M1 means that instruments from different manufacturers will read alike. The M1 mode greatly reduces inter-model differences, so your inline press spectrophotometer will now be a closer match to your press-side handheld device. And in other situations, the L*a*b* measurement of your X-Rite eXact will match your customer’s readings even if they are using a Techkon SpectroDens. This applies for all media types whether they contain OBAs or not. Arguing over spectrophotometer differences is a thing of the past—if you use M1.
The ISO standard for the M measurement modes was published in 2009, but commercial spectrophotometers did not become mainstream until very recently. All manufacturers have released new instruments to meet the standard and offer the M1 measurement mode. Some device names have been changed to indicate their updating, e.g. the X-Rite i1Pro has become the i1Pro2 and i1Pro3, and the X-Rite iSis has become the iSis2. In the pressroom, X-Rite has replace the traditional 500 series instrument with the eXact.
Characterization data and ICC profiles have been updated and are now defined in terms of M1. If you change your color target from GRACoL 2006 to GRACoL 2013 (which you should do), the new data is provided in terms of M1. All new datasets and ICC profiles are now based on M1—If you have an M0 workflow, you can’t be printing to a standard!
Light booths have been updated so they agree with ISO 3664. Light booths should have been fitted with new fluorescent lamps or LEDs that meet ISO 3664, which is basically D50 in the light booth. No more blue or yellow casts in your proofs and pressruns.
There is no longer the need to have OBA-free proofing papers. The M1 measurement mode is a “complete color measurement” which takes into account any OBAs in the paper. This means we don’t have to worry about proofing paper, and whether the press stock has OBA or not, whether the viewing booth has UV light, etc. Just measure in M1 and the press stock, proofing media and lighting all take care of themselves.
Some packaging printers have chosen to use the M2 measurement mode, which is the UV-excluded mode. This means they can never color manage a material that contains OBAs, and that means the printer can never print to a modern standard and target GRACoL or SWOP or a CRPC. M2 excludes UV, but sunlight contains UV, so the package just printed will change color as a customer leaves the store!
If you are still not convinced, D50 is the basis for the Profile Connection Space in the ICC architecture—It is the reference connection space, which is M1! All of these points make M1 the most desirable mode for measuring and managing color today.
Photoshop & Pantone
There is one fly in the ointment—Photoshop. The Pantone digital libraries for Solid Coated, Solid Uncoated, etc. specify a spot color in terms of L*a*b* that allow for the swatch to be accepted and processed in color management and workflow solutions. A Photoshop dialog shows that Pantone 516 C, for example, has L*a*b* values of 82, 19, -9. But the L*a*b* values shown are not M1—Photoshop displays the M2 L*a*b* values for Pantone spot colors.
The Pantone digital libraries are issued in three measurement modes—M0, M1, M2. Vendors such as GMG and Esko are provided the library in all three flavors. The vendor is free to use these as desired and most responsible software will use M1, and/or allow the user to select the measurement mode of their choice.
It seems that while Pantone provides the digital libraries to its customers, it doesn’t care how they use them and we see that Photoshop has decided to use the M2 library. It is suggested that Pantone should ensure that all licensees of their digital libraries use the libraries properly. McDonald’s, for example, would not let a franchisee serve a Quarter Pounder with Uncle Bob’s best barbecue sauce! Pantone has full responsibility to ensure the end user can obtain unambiguous specification of color—isn’t that what the Pantone system is supposed to do? The default measurement mode today should be M1, and Photoshop should allow the user to change mode or clearly state the values are M2. I hope somebody from Pantone and the Photoshop team reads this and addresses the issue. (And while you are there, get Photoshop to show two decimal places, please!)
Check out some really neat things from the chart (above/below/some direction based on web layout).
Look how different the L*a*b* value can be if a swatch is measured in the different measurement modes, b* = -9.32 or -15.65 for the same swatch. This clearly shows you the effect that measurement mode has can have on the L*a*b* value.
Note the big difference in b* value between the M1 and M2 mode—15.65 vs. -9.32. Remember that M1 is UV-included and M2 is UV-excluded, so the big difference here is indicative of a sample that contains OBAs, and in fact we know that the Pantone swatch books are printed on OBA-rich media, so this makes sense. For those familiar with the L*a*b* diagram, note that a larger b* value (-15.65) in M1 mode indicates that the sample is more blue, which is a direct result of optical brighteners and fluorescence.
Usually, in many areas of color management, it doesn’t matter what setting you use, as long as you—and everybody involved—know what you are using. For example, some users prefer D50 while others like D65. But for the reasons explained in this article, this does not apply to the measurement modes—you will have problems if you use M0.
There is no reason not to use M1 today. All color datasets and ICC profiles have been updated and the new datasets are only available in M1. M1 mode is available within the new generation of spectrophotometers. Light booths have been updated so they agree with ISO 3664 and are M1 (D50). The ICC architecture works in D50. All color workflows—from Esko Equinox to GMG OpenColor—support M1.
The M1 measurement mode has been accepted worldwide in all areas of color measurement and management. To avoid errors and unnecessary confusion that originate from differences in the measuring instruments, please switch to M1 today. M1 is the most desirable mode for measuring and managing color.