If one looks at a K vs. L* plot (see attachment), then it becomes clearly evident that this device obviously has not been linearized. The CLUT grid alone can never fit the curvature accurately, in particular a coarse grid (-ql) cannot. Thus one should not even consider using "-ni" with this data set; pre-linearization curves are essential here ("-no" on the other hand does not make so much difference). And using -qm or -ql instead of -ql helps of course further to fit the data a couple of 0.1 dE more accurately on average. If I additionally replicate the white patch in the .ti3 file 16 times, then I get -qh => WP 96.994025 0.765836 -2.935014 -qh -no => WP 96.976569 0.764789 -2.935626 -qm -no => WP 96.090594 0.746270 -2.901280 -ql -no => WP 95.832088 0.782419 -2.978553 which are all not so much off from 97.510 0.78000 -2.9600. (normally one should of course not just replicate a single measured white patch, but rather one should add additional measurements for white, taken at different locations on the sheet or possibly even from different sheets (note, a huge target may span several sheets too), in order that the actual variation can be honored by the profile => targen -e ...). The given data set also looks somewhat noisy. I would not expect that even the -qh profile can predict the color of printed patches much better than about 2-2.5 dE on average (note, even the self-fit error to the measurements is about 1.4 dE, and computing a cross-validation also suggest that decreasing the smoothness is rather not an options for this data set, but would only fit more of the noise in the measurements, resulting rather in a worse prediction of the average device behaviour, than improving things). I have seen data sets from professional inkjet printers, which did fit the spline model noticeably better than your data set. The missing device linearization is indeed one issue (and here is possibly some room for improvement), but given the already large number of patches, my feeling is that there might be also a repeatability issue (either of the printer or the measurements). Btw, conspicuous is IMO also the rather strong color tint of the black ink: 1 0.0000 0.0000 0.0000 0.0000 97.510 0.78000 -2.9600 32 0.0000 0.0000 0.0000 10.000 77.730 3.0000 -3.8100 33 0.0000 0.0000 0.0000 20.000 60.610 4.7900 -4.9500 34 0.0000 0.0000 0.0000 30.000 47.130 6.4200 -6.2700 35 0.0000 0.0000 0.0000 40.000 35.820 7.5600 -7.6600 36 0.0000 0.0000 0.0000 50.000 27.780 8.0000 -9.0800 37 0.0000 0.0000 0.0000 60.000 23.090 7.1900 -10.030 38 0.0000 0.0000 0.0000 70.000 18.640 6.7800 -10.690 39 0.0000 0.0000 0.0000 80.000 16.300 5.6100 -10.650 40 0.0000 0.0000 0.0000 90.000 15.010 4.4900 -10.490 41 0.0000 0.0000 0.0000 100.00 14.230 3.4100 -10.260 John Weissberg wrote: > The L value for the wtpt tag varies quite dramatically depending on the > values used for the q and n tags. This amount of variation seems > excessive to me. > > Here are some values below using various settings for the parameters of > profile: > > profile -v -ql -bl -kr -l333 canon9950 > Lab(wtpt): 92.496330, 0.622382, -3.016244 > > profile -v -ql -bl -kr -ni -no -l333 canon9950 > Lab(wtpt): 93.403267, 0.365175, -3.695083 > > profile -v -qm -bl -kr -l333 canon9950 > Lab(wtpt): 89.306440, 0.563566, -2.679620 > > profile -v -qm -bl -kr -ni -no -l333 canon9950 > Lab(wtpt): 92.164165, 0.582095, -3.329186 > > > All calculations performed with Argyll 7.5