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Author Topic: QTR linearisation data translated to a Qimage print filter  (Read 14841 times)
Ernst Dinkla
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« on: April 24, 2011, 12:36:58 PM »

There is a difference between the B&W output of my HP Z3100 and the Z3200. The first has a perfect linear B&W output after calibration. The second not. This is most likely a general difference between the two models, more reviewers and users observe the difference. As there is some advantage to build B&W profiles on top of linearised B&W output I am trying to get that right for the Z3200. QTR doesn't support HP printers but I can use some tools of it. I try to make use of the spectrometer integrated in HP Z models for that task for my own convenience but also to help HP Z users later on and extend QTR's tools as well. With QTR's linearisation and ICC profile tools + customised greyscale targets for the HP Z models it is quite easy now to generate QTR linearisation data and B&W "ICC" profiles. So far based on the 21x4 random greyscale target, there is no reason why an 51x4 random target would not work either so  that one will be added. I would like to have a fast translation of the linearisation data to a Qimage print filter. Is there a tool for a translation like that?

A typical QTR linearisation file looks like this:

QTR-Linearize-Data version 2.7.0.0

File: C:\EPWSMCGATZ3200Greyscale2-out.txt

Step   Dens   Lab   A   B   

0.00   0.055   95.21   0.15   -0.05   -                            ba                          L  +

4.71   0.115   90.24   0.13   -0.27   -                           b a                       L     +

9.80   0.171   85.71   0.25   0.03   -                             b                    L        +

14.90   0.231   81.13   0.38   0.00   -                             ba                L           +

20.00   0.293   76.63   0.45   0.02   -                             ba             L              +

24.71   0.351   72.57   0.56   -0.02   -                            b| a          L                +

29.80   0.404   69.04   0.63   -0.10   -                            b| a        L                  +

34.90   0.477   64.45   0.75   -0.21   -                            b| a     L                     +

40.00   0.534   60.99   0.82   -0.27   -                           b |  a  L                       +

44.71   0.622   55.97   0.86   -0.55   -                          b  |  a                          +

49.80   0.757   48.90   0.82   -0.92   -                         b  L|  a                          +

54.90   0.850   44.43   0.78   -1.02   -                        bL   |  a                          +

60.00   0.937   40.52   0.75   -0.97   -                       L b   |  a                          +

65.10   1.044   36.04   0.83   -0.99   -                    L    b   |  a                          +

69.80   1.173   31.16   0.92   -1.01   -                 L      b    |  a                          +

74.90   1.294   26.97   1.02   -0.97   -               L         b   |   a                         +

80.00   1.464   21.71   1.10   -1.02   -            L           b    |   a                         +

85.10   1.703   15.39   1.21   -0.84   -        L                b   |   a                         +

89.80   1.958   9.82   1.15   -0.93   -    L                    b   |   a                         +

94.90   2.249   5.09   0.58   -0.76   -  L                      b   | a                           +

100.00   2.407   3.53   0.36   -0.74   - L                        b  |a                            +



LINEARIZE="95.213524 90.2394255 85.71437475 81.13369925 76.63015175 72.57275 69.04462625 64.4461745 60.993701 55.96749975 48.89785 44.43135 40.52172475 36.04129875 31.15587525 26.965 21.708675 15.386225 9.818 5.09274 3.5332925"

It is Z3200 HP Vivera PK, Grey, Light Grey, ink on the non-FBA Epson Proofing White Semimatte RC paper. Data made with HP Z3200 Color Center print, scan, measurement export feature from a 21x4 scrambled target and QTR's linearising tool.


met vriendelijke groeten, Ernst


New: Spectral plots of +250 inkjet papers:

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm

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Mack
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« Reply #1 on: September 17, 2013, 05:34:27 PM »

Oddly, I seem to be right behind Ernst in looking for B&W printing stuff and found this old unanswered thread in searching.  Seems it must be somewhat popular as it has had over 1,200 reads but no response until now.

The QTR stuff is sort of outdated for the new "i1 Pro Photo 2" I find.  It won't show 21 step in those 21 step targets in a strip mode scan, maybe 20.  Something to do with the way the targets were made up maybe.  It suggests using the old outdated x-rite ProfileMaker 5.0 software too over the new stuff.  Dunno.

Right now I've been fighting the "burple shadows" in the 21 step targets that transition from a warmer yellow highlight, but found I can tune the inks via the Curves in Editor.  The Eyedropper on a target step will show on the Curve as a "Loc" (Location) and a "In" (RGB value), the third window "Out" (in RGB) is the one I can set to add or subtract a given color at that selected eyedropper point.  I can see and set each point in a 21 step tablet there and Save it out as a Curve filter.  Example:  Change it to maybe 0.5 plus or minus in the "Out" window and you can see which way it needs to go to make that step neutral.  In my case, I have to have the Blue selected too since I am working on that curve.

I haven't gotten to the Linearization part yet as adding and subtracting a color of ink seems to influence the readings somewhat.  I don't know if you can change the brightness (Luminosity) of each of the 21 steps in the Curve tab and save the color & linearization both, but maybe you can?  Might be too tedious to do the 51 step wedges other than just seeing if they do have a gradual density change.

In the "QTR User Info" (Pages 25-26) PDF file, they show suggested values in a Linearization array window for dMax of the black from 1.600 to 2.400 in 0.050 steps.  Would be interesting if one could move the curves somehow and Save them as a Curve filter or general Filter to be applied when needed.  The Levels tab of QU doesn't provide for a Save as far as I see, so it may be need to be done in the Curves tab to Save it?

I'm not too happy with QTR RIP GUI interface (Clunky old Drag-and-Drop Windows 98 looking thing.) as the images I get out of it are soft and not as sharp as can be done with QU.  Really is a remarkable difference between the two there, and QU has a much better sharpening engine and adjustable too.  The tone density between the two is substantial too (i.e. the QTR RIP using their quid extensions and no OEM print driver vs. an ICM made out of it for QU/whatever using an OEM print driver.).

Too bad Mike hasn't added some B&W tab on QU for the Color and Linearization construction somehow for us B&W printers.  Should be far better than some RIP packages out there if it were there since he has the best sharpening I've seen using QU. (I did see the sepia filter buried in QU somewhere, but it is more like a gold "Sundowner filter" as it is way too much sepia if it is.)


Mack
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Ernst Dinkla
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« Reply #2 on: September 18, 2013, 08:54:17 AM »

Two and a half year old message you used!

The best way to get B&W print control and consistency in output is a printer that uses some to several monochrome inks and a driver (mode) that controls them in the first place next to some ink hues for color toning, so Epson's ABW, QuadTone RIP, Bowhaus True B&W for Canons. Driver Color mode + ICC color management is a route that is much harder to keep consistent for B&W prints even with 3-4 monochrome inks aboard. Exception is the HP Z3100 as its media presets already have an extreme black generation from highlights to shadows in Color mode, the B&W mode is however better, especially the Dmax on matte papers.

The above is the best I can say about your route. What is written below is more a reply on my old message and for my purposes I have the tools I need.

Several times I have tried to use Qimage's (Ultimate) editing tools for B&W print optimizing or B&W custom ink sets. Creating special linearisation targets with less patches than 21 to match Qimage's Curve tool control points. The main obstacle is the Qimage Curve tool that is very different to the Photoshop Curve tool and in my opinion too limited for that task (and in general for more precise editing tasks). The Photoshop Curve tool is the one most B&W custom solutions work with.

In the end I use the QTR generated B&W profiles ("ICC" RGB version) in Qimage Ultimate for my Z3100 + the HP B&W driver mode. Based on the QTR 21 step target>linearisation>profiling method. Similar for the to quad inks converted HP OfficeJet Pro K5400. In that case the B&W profile has the Photoshop created partitioning curves aboard + the profile based on the linearisation target data. Normal HP OfficeJet Pro driver in Color mode, either using 3 inks for gloss or 4 inks for matte prints.

There is another thread next to this one in the forum about a Complete Qimage workflow. If there is one thing I would like to see changed is the Curve tool so it is like the Photoshop one and compatible so ACV files can be exchanged. Or a choice that one can use the Qimage version or the new version so nobody has to get upset about that proposal. I would then try Qimage again for editing. This is not about RAW workflows that have to go smoothly and fast, I think that the Qimage method for that is as good if not better than the best RAW based programs. I also understand that my use of a curve tool as described above is not a common one. There are jobs that fall in between and then my first choice is Photoshop for the time being.

--
Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
July 2013, 500+ inkjet media white spectral plots.

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Mack
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« Reply #3 on: September 19, 2013, 04:18:53 AM »

Get these first:

21 Step Grayscale L* gamma target: http://cameratico.com/media/images/articles/17/21-step-Lstar-grayscale-target.tif

Linearization Spreadsheet: http://www.piezography.com/PiezoPress/blog/piezography-k7-inks-and-curves/checking-your-linearization/

Spreadsheet download for Excel or Open Office or LibreOffice (freeware): http://www.piezography.com/Linearization-Checker.zip


Entering my own L*ab values in ColorPort (x-rite software) with their "i1 Photo Pro 2" on Spot mode into the yellow window of the spreadsheet above, I got a Before and After of the linear line.  Took a bit of work in the +Curves tab in Qimage Ultimate to get it right, but the line is looking pretty darn good using the data from reading the 21-step target above.

I wasn't happy with the targets in QuadTone RIP as they appear to be uneven in density in each square (More like a graduated ND.).  Outdated to work with the Scan mode of the newer i1 spectrometer heads and software as well.  The above L* TIF step-wedge image is smoother and larger for targeting in Spot mode too.

If you see the Black Line to the right of the magenta one, apply a bit of negative RGB at that part of the line in the +Curve window in Image Ulitmate.  If it is to the left of the magenta line, apply a few points positive to the value for that density in the +Curve.  The Eyedropper will help you find which 21 step you need to target and change the "Out" value in a few steps (1 or 2 if close to the line, 5-6 if further away).  Print target again with the newly Saved Curve (Use some name) in QU, and enter new L* values into the spreadsheet yellow blocks again and see if it is closer once dry.

Now I'm off for the Color Change (Purple shadows) and see if I can clean that up a bit in +Curve window too?  Maybe use the Blue channel only and leave the L* value alone (Use all the RGB numbers in the +Curve editor pane for the linearization part.).


Attached:  Screenshot of Epson 3880 with the 4 colors of black/gray ink (Only using the 3 and not the Matte now).  You can see the two charts made from Open Office and the linearization of the three inks:  Without the +Curve mods, it is outside the linear line on the right and not straight.  With the tweaks made to the RGB numbers for the steps on the Curve line and saved as a Curve filter, it is almost perfect! You can see the slight dip in the straight line part of the +Curve window (Little circular dots where it has been tweaked downward.) in the upper-right Editor window where I applied negative RGB numbers in the "Out" pane which moved the black line to the left under the magenta one in the spreadsheet to make it linear.

Purpose of this is too keep the ICM paper profile that I generally use, and will also let me add coloration inks to the B&W images later on same paper as a filter (or maybe along with the Curve too?) such as Sepia, Selenium, Warm, Cool, etc.  With the way the ICM profiles are made in QT RIP, that ability is sometimes hampered as it messes with the RGB portion so you may not get the color you want, plus I get to keep the ability of the better sharpening engine in Qimage Ultimate which you lose with the QT RIP interface.  Smiley

Whew!


Mack
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Ernst Dinkla
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« Reply #4 on: September 19, 2013, 12:45:33 PM »


I wasn't happy with the targets in QuadTone RIP as they appear to be uneven in density in each square (More like a graduated ND.).  Outdated to work with the Scan mode of the newer i1 spectrometer heads and software as well.  The above L* TIF step-wedge image is smoother and larger for targeting in Spot mode too.


Inform Roy Harrington about that flaw I would say. I did create my own step targets to check on ink bleeding etc too but I have never seen irregularities in the QTR target patches in Photoshop or seen comments by users about that.

http://groups.yahoo.com/neo/groups/QuadtoneRIP/info

You are "linearizing" etc the Cone dyes in the 3880 that way ?

--
Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
July 2013, 500+ inkjet media white spectral plots.
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Mack
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« Reply #5 on: September 19, 2013, 05:30:13 PM »

Ernst:

Yes, the above screen snap was linearized in Qimage Ultimate alone based on the readings off the 21-step L*gamma chart (It is L*ab based in readings and very close.).  I used the TIFF step-wedge link above and was using the spreadsheet by Jon Cone (in the above link) and using his dye inks in the the 3880 (I'm using the normal color DYE inkset array, not the K7 gray inks, fwiw, as I want to adjust the coloration a bit at times as in toning.).  I just changed the +Color line a bit in Qimage to force it linear.  I also re-did Cone's linear regression spreadsheet to read 1 to 21 (from the 0-100 numbers) under "Steps" so I can go immediately to that step in QU and move the +Colors tabs "Out" numbers a bit.  I saved it as a "Curve filter" under the +Color tab to apply later when I mess with it.

For fun, I entered the step-wedge numbers off a QU generated print from the above method and fed them into the QuadTone RIP program and the numbers from its Linearization came out perfect too needing no adjustment.  So the QU way above and its image seem to be happy in QTR as well.  I managed to smooth out that screenshot's non-linear hump in the screenshot just using Qimage Ulitmate's +Curve tabs "Out" RGB numbers and Jon Cone's regression spreadsheet.

Ernst, if you have an image to print, try printing it in the QuadTone RIP and then print the same image in Qimage Ultimate.  The sharpness in QU is very apparent at my end  I leave the QU 'Sharpness' set to around 12 and I shoot with a Nikon D800E so the sharpness should be apparent out of that camera.  The QuadTone RIP looks to be really, really soft and a bit out of focus for whatever reason with the same image.  Not too happy with it side by side against Qimage which is far sharper so I'll stick with QU as Mike seems to keep it updated and current whereas QuadTone RIP seems to be iffy at times, plus it hangs in Task Manager > Details in Windows 8-64 as multiple Quadtone.exe and some other *.exe that needs to be shut down hard (End Task) for those multiple entries.  It's just not a well executing program, too old maybe, and support via their Yahoo! group is very slow to non-exisitant too.  It needs a lot of current TLC, and some of the Info/User files were written way back in April 25, 2005 for some of it and do not apply to current hardware.

I do find some errors that pop up in QuadTone RIP to that date back to 2009, i.e. the "Error I/O 32" one that still haunts the program.  The GUI for it is sort of kludgy too on seeing the size of the postage stamp-sized image on it too as the GUI isn't sizable in Windows 8-64.  I'm sure Mike could do a far better job on the programming if we can convince him on some B&W RIP program or addition to QU since he has already has a good one for Color with QU.  Someone should give him some Epson printer loaded with K7 gray inks (haha!) and a truckload of Canson paper.  Plus, we'd have Terry and Fred to pick on too when it blows chunks!   Grin

(my $0.000002 ... and sundry subliminal hints too.)


Mack
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Ernst Dinkla
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« Reply #6 on: September 20, 2013, 09:54:19 AM »

So is the Cone dye black Dmax issue solved as you now are linearizing that inkset?

Did you inform Roy on the QTR target patches issue already?


--
Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
July 2013, 500+ inkjet media white spectral plots.
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Mack
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« Reply #7 on: September 20, 2013, 09:05:17 PM »

Ernst,

I've given up on QuadTone RIP as Qimage Ultimate has a far better sharpening engine.  Try the same print from both and compare the two programs.  No sense dealing with "soft and fuzzy prints" from QuadTone RIP that cannot be adjusted.  Their forum is sort of slow too, as this one has jumped almost 150 reads since I restarted this thread in 2-3 days (Lots of lurkers?).  Got tired of the "Error I/O: 32" messages (Dating back to 2009?), and it hanging up in Task Manager too needing an "End Task" to kill multiple hangs of quadtone.exe too.

I believe I have addressed the "dMax" using Qimage and using the Epson driver below.  Needed to redo some stuff too.

So far I made a couple of changes.

1. The link for the 21 Step Lab stepwedge above is in a Gray Gamma 2.2 mode.  As such, it will not allow me to change any coloration to it in QU.  I saved it in Adobe RGB 1998 as a TIF and all is well there now.  I checked to make sure the L values remained at 5 points in each step increase/decrease and they do.  I also added the step numbers to the chart as I got tired of counting steps, and also Adobe RGB 1998 in red so I know I am using the correct one and not the linked one above that only deals with B&W and no color additions I may apply in QU.

2. For Jon Cone's Linearization spreadsheet above, I changed the 1-100 scale for the steps (Bottom, x-axis) to 1-21 to match the steps in the 21 step-wedge above.  Makes it easier to pick out which one to change the "Out" RGB value in QU Curve portion (Making it a more positive RGB number moves the black line up on the L scale, negative moves it down on the L scale.  If the black line is touching the magenta, 1-2 points might do it, if there is a lot of white space between them, maybe 4-5 points is needed.

3. My initial dMax values weren't that low (or black) on the Canon Glossy Paper which I used for this experiment.  However, within the Epson driver there is a "Color Density" adjustment and moving it up the percentage scale made the black Step 21 target definitely blacker.  I got the following L (Luminance) dMax values off the x-rite i1 head below for Step 21 by increasing percentages (Lower L# = blacker):

0%  L=12.113
10% L=9.753
20% L=8.29
30% L=7.626

I seem to recall that anything less than 1 difference is where you can settle on from some QuadTone RIP articles without flooding the paper with ink.  I settled on the 20% More Color Density value (to be set in the Epson Driver Properties > Paper Configuration Page window) as the 30% wasn't as great (1 value) as from 10% to 20%.  This is using my initial profile written for the Canon paper too so I suspect my initial setup is buggered and I need to redo the i1 Photo Pro 2 reading and alter the settings in the i1 Profiler software program to produce a blacker black (I think there is a couple of settings in the i1 Profiler to do that?).  I use 20% more Color Density now, although it might be a bit better at 25% density, but that's debatable.

Then I ran a new linearization reading for the step wedge at 20% more color as I could see the black getting bunched up on the right of the wedge and darker overall.  Linearization line moved to the left.

Tweaked it in using Curves and the Eyedropper.  Just raising and lowering the "Out" setting in the Curve for each step gave me the screenshot below.  I got more dMax over the above screenshots, and it is very linear (I can see a bit of the black line at step 16 on top and a bit under at step 19, but it is pretty darn good overall.).  Maybe even more so than QuadTone RIP produced one since I can tune each of the 21 steps in Qimage individually and not follow a "curve of ink grey colors" as in QuadTone RIP.

I have been using an expensive x-rite "i1 Photo Pro 2" to do this L*ab reading stuff, but their cheaper ColorMunki Photo shows the L*ab values in the upper right hand corner of the Color Picker program within it.  It should work too.

Later, I will attack the bluish color I see in the steps around 10 to 18 and see if I can negate that color.  I should be able to do this in Qimage too and maybe just address the color at those steps too.  Dunno.


Mack
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Mack
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« Reply #8 on: September 21, 2013, 01:59:28 AM »

Additional:

Well, I succeeded in getting rid of my "burple shadows."  It can be done in Qimage by altering the Curve in the Blue channel with the line.

I had to go into Curve, and select "Blue" instead of the RGB that is also saved there for the linearization above.  You need to set a boundary to work within and alter the Blue curve else the entire line will shift without the anchor points.  Setting outer anchor points allowed me to alter the mid-tones to subtract the blue and add more yellow in the middle.  I don't mind a cool or blue dark black, but a yellow or warm highlight that becomes a blue in mid-tones is sort of annoying.

So I looked at the step wedge and called step 9 and step 18 my 'anchor points' so I could alter in the middle of it to more yellow.  I had to enter some number at those two steps so I entered only one point lower in the "Out" window in QU at each step found with the eyedropper which stored that value so the line would not move from 1 to 9 and 18-21.  Just everything between 9 and 18 would be shifted next.

I selected step 11 and step 15 to drop the blue.  So I entered about 5 points less than shown in the "Out" box on the Blue channel which added more yellow.  You can see the shift if you change it by 50 points to make sure you are going the right way.  Doing the same -5 points in Out at 11 and 15 dropped the middle of the line to add more yellow in the middle and got rid of my "burple" middle and dark tones.

You can see the shift in the upper right window of Curve in the attached screenshot.  Notice the four circles on the line black line.  Two outer are set as 'anchors' to lock the ends of the line line down, two inner circles (one in red) where I lowered the Blue channel RGB value (-5 points for me) in the "Out" window for step 11 and step 15.

I saved that as a paper correction name in Curve too.  "Epson 3880 Dye ink - Canon Glossy BW Correction".  That''s it.  I can call it up later when I do B&W prints on that paper.

Now if I want a nice "Sepia" tone, I can open the image (Preferably a gamma of 2.2 in B&W, but important to save in Adobe 1998 RGB so color can be used later.) and open the above Saved Curve Filter too.  Then I can go into "+Sel. Color" tab and change the N(eutral) setting to R=1.01 G=0.92 and Y=0.83 and print it.  All nice and linearized and odd ink colors neutralized out via my newly saved Curve filter above, and a Sepia tone added too.

Who needs QuadTone RIP for B&W when Qimage Ultimate can do it and maybe refine it even more - plus it is sharper too!  Smiley


Mack
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