I followed through with Mark S.'s request by building a custom ICC profile from the ACU printed test target using i1Profiler set to it "Colorful" default setting. The TC918 target has a 9x9x9 grid of RGB color patches that gets used to build the profile. I'm not sure whether i1profiler uses all 918 patches or just the 729 patches of the grid, but very decent profiles get built with the TC918 target if the printer is running properly and the target was successfully printed with color management turned off.
I have attached two screenshot views comparing the color gamut volume of Canon's generic supplied Pro-1 printer profile for the Canon PPPSG paper to the gamut volume created by the custom i1Profiler/TC918 profile I built with the ACU printed color target. The red color in the graphs is for the generic profile. The Blue color shows the gamut volume of my custom made profile. As can be seen in the two views, the custom profile produced a slightly larger gamut volume than the generic Canon profile on my Pro-1 printer. However, this is probably not of practical significance. The more important fact is that the overall gamut volume shape of the two profiles are totally consistent with each other which would not occur if ACU had failed to produce a non color managed target outcome.
That said, gamut volumes only address the potential of the system to make colors not the accuracy of the colors produced on the print by the profile. So, I did a quick and dirty test to verify and compare the printed output accuracy of both profiles. I made two color prints using a digital image of a Macbeth ColorChecker Chart with colorimetrically perfect embedded lab values of all the colors and using perceptual rendering intent for both prints. One print was made with the Canon supplied Pro-1 generic profile for the PPPSG paper, the other with the custom i1Profiler-built profile. Both prints showed the merits of color managed output, but to my eye under controlled lighting the generic profile produced a noticeably darker print than the custom profile yet with hue and chroma accuracy being in close agreement between both prints. I preferred the lighter version created by my custom profile and when placing both prints side by side an actual ColorChecker chart, the lighter version of the print was the better overall match, IMHO. I then spot checked a few of the color patches with an i1Pro2 spectrophotometer to confirm my visual impression of both prints. Here are a few measured values. I could have measured all 24 patches, but these three pretty much tell the story. Note the L* values in particular. The generic proflle was printing patches 4-6 L* units darker than the custom profile throughout most of the midtone tonal range, while a* and b* values are very close for both prints. The custom profiled print is the colorimetrically better match to the actual ColorChecker reference target owing to the significantly better agreement on L*. Most viewers would prefer the lighter print if they saw it side by side the actual ColorChecker, although without a direct comparison many amateur printmakers would probably be satisfied with either print.
Actual Colorchecker value Printed value Generic ICC, Printed value Custom ICC
mid tone gray LAB = 51, 0. 0 LAB = 42, -1, -1 LAB = 48, 0, -1
Black patch LAB = 20, 0, -1 LAB = 14, 0, -2 LAB = 18, 0, -2
Skin tone LAB = 66, 18, 18, LAB = 58, 18, 19 LAB = 64,16,16
So, to summarize: I was able to use ACU running under Mac OS El Capitan, and also with the latest Pro-1 firmware, and the latest Pro-1 printer driver to successfully print a non color managed ICC profiling target. The 918 color patches were then measured and used to make a properly performing custom ICC profile, one that essentially exceeds the quality of the generic Canon supplied profile on my Pro-1 print unit by virtue of better tonal fidelity while maintaining comparable hue and chroma accuracy.
My conclusion is that Simon's issue is unlikely to be a bug in the Canon driver (although I've seen Canon drivers with real bugs before
) nor in ACU, otherwise I should have duplicated Simon's results and concurred that ACU wasn't giving proper output. That leaves the million dollar question. Why is Simon unable to duplicate my results given that we appear to have exactly the same OS, same printer model, same printer driver, and same ACU software to "print as color target"? Simon, if you haven't already done so, try deleting your printer driver in the Mac System preferences pane, rebooting your computer from full off mode (not just a restart), and then re-add the driver back into the Mac's printer cue. This trick goes a long way to curing many strange printer woes on a MAC, but I'm stumped to suggest anything else if that doesn't work. Hopefully, Canon can give you some other ideas.
best,
Mark
http://www.aardenburg-imaging.com