For some reason I cannot get black to print maximum black using Qimage Ultimate 2023.103, and I think it is likely to be some setting issue I'm misunderstanding.

I'm trying to assess B&W printable range and linearity. I made a test image file with 10 patches from pure black to pure white, i.e., L* = 0 to L* = 100 in steps, all with a* = b* = 0. Lightroom's Develop module confirms that the file's black patch is L* = 0, and all the other patches are +/- 0.2 from the desired L* values. An RGB color-picker likewise confirms that the black patch is 0,0,0. ICC Profile Inspector reports that the ICC printing profile used has an L* minimum of 5, and a visual inspection of a plot of the profile at the ICC View website confirms this.

I printed to a Canon Pro-100, using the same driver settings I use to build ICC profiles with my X-Rite ColorMunki Photo spectrophotometer, color matching = none etc. In Qimage I have it set for relative colorimetric rendering intent and black point compensation--which I think should make the 'black' patch come out about L* = 5. By actual measurement with the ColorMunki, the 'black' patch is L* = 9. I got similar results with two standard papers, Canon Pro Luster and Canon Glossy II. I went back and re-measured some old profiling targets, and indeed the ColorMunki reports as expected the 'black' patch is about L* = 5.

Am I wrong in thinking that using relative colorimetric with black point compensation, an area of L* = 0 in the file should print as maximum printable black i.e. about L* = 5? Is there some other setting you think I might be missing?

Thanks!

Hi
The latest version of the iStudio software lets you create a black and white profile in the same way as a colour *one, by printing pages of coloured squares.* I've found it to work exceptionally well in producing pure black *and white prints.*. The latest version is 1.5.1, available here:

https://www.xrite.com/service-support/downloads/i/i1studio_v1_5_1

Brian

PS I've got another problem now, my keyboard is inserting random asterisks. 

Thanks for all the thoughts, and to update my issue:

(1) I realize that printable L*min will never be 0, although with a few combinations the ICC profiles indicate it should get down to about 3. With the Pro-100, Canon Luster, and Canon's ICC profile (the file is CNBBDUA0.ICM), the profile indicates L* min = 5, and that's close to a* = b* = 0 (actually about at b* = -1). At precisely a* = b* = 0, profile-indicated L* min is about 5.5. I'm basing this on observing the 3D gamut plot, rotated and enlarged, at https://www.iccview.de/, a screen capture of which is the first attachment. But measured with the ColorMunki, a file printed in Qimage with rel. col. + BPC, the printed image patch of L* = a* = B* = 0 measures L* = 9.

Similarly, with the Pro-100, Canon Glossy II, and Canon's ICC profile (the file is CNBBDMA0.ICM), profile-indicated L* min = 5, but that's at about a* = 0, b* = -3. I had written to see the second attachment, but with it the board reported I'd exceeded my allocated 256 KB. At precisely a* = b* = 0, L* min is about 7. The printed patch of input values L* = a* = B* = 0 measures L* = 11.

So it's seems like there's an issue significantly beyond L* min not being neutral and/or being substantially above 0.

(2) I'm aware of, and use, the X-Rite software's ability to make special B&W profiles, and I intend to do more testing, partly around that. But to try to isolate variables and start with the most current, widely-used combinations, I decided to start with Canon's main papers and Canon's own profiles. My sense and limited testing indicates that X-Rite-built B&W profiles deliver slightly more neutral grays but no increase in Dmax / decrease in L* min.

(3) FWIW and as a comparison and control, I got two targets printed on Ilford RC silver halide paper, Pearl surface from Mpix (on which the target patch with input values L* = a* = B* = 0 measures L* = 7, a* = 1.0, b* = 2.4) and Glossy surface from Fromex (on which the target patch of L* = a* = B* = 0 measures L* = 8, a* = 0.8, b* = 2.2). Also, taking repeated measurements, over different days and after different calibrations, with the ColorMunki Photo shows that all measurements are within about +/- 0.3 of each other, and many are closer than that. In other words, I can't vouch for this spectrophotometer's accuracy (reporting the true value), but I can vouch for its precision (repeatedly reporting the same value).