general question about gamuts

[MonsterBaby]

when i look at a paper profile in 3d and see a very well formed cubical shape with wide shadow coverage... does this really mean that i can actually "see" and use this wide gamut?

f.e. the RGB profiles that i create "look" very nicely shaped. but in reality when printing the shadows are often blocked.

when i create a LIN+CMYK profile for a RIP.. in 3d the dark gamut doesnt look as large.. but when using it i get better shadow details.

so my question is: can i actually use this large gamut that an ICC profile shows?

hope this is kinda understandable :-).. and will open an interesting conversation

[gromit]

.e. the RGB profiles that i create "look" very nicely shaped. but in reality when printing the shadows are often blocked.

A 3D plot doesn't tell the whole story. There's a number of possible reasons for blocked shadows, the primary one likely being the gamma of your file. For example if your file is in a gamma 2.2 space (Adobe RGB (1998) etc), any values less than about 10 will print as black because of the space's flat toe. Look at the corresponding L* values. The next reason is poor linearization in the printer itself. A linearization file or the profile itself can only do so much in opening this area up. Lastly, if printing on matte papers, shadows will need to be compressed to maintain the L* 50 midpoint, namely the overall image tonality is retained but something has to give in the shadows the higher the blackpoint is from L* 0.

Consider instead using working spaces based on L* and calibrating your monitor to the same. Also look at later model printers (Epson x900 for example) which perform in a more linear fashion than say the x800 series.

[digitaldog]

Consider instead using working spaces based on L*...

Such as? What about coming out of an Adobe raw processor that has no such spaces, convert again? And what about in this case, its not going to be L* out?

[gromit]

Such as? What about coming out of an Adobe raw processor that has no such spaces, convert again? And what about in this case, its not going to be L* out?

Adobe is pretty backward in this respect but you can Export from Lightroom to (say) eciRGBv2. Just knowing how the gamma of your space affects shadows is a start.

http://www.eci.org/doku.php?id=en:colourstandards:workingcolorspaces

[digitaldog]

Adobe is pretty backward in this respect but you can Export from Lightroom to (say) eciRGBv2. Just knowing how the gamma of your space affects shadows is a start.

Just for L* encoding? Deal breaker. There’s still the issue of L* out (which isn’t the case).

[MonsterBaby]

ok. thanx for the input about the gamma. i work in ProPhoto with gamma 1.8

but i like to come back to my original comparising question.

i would like to know why the gamuts of the profiles look different.

is this also because of the linearization that is better when done by the rip then the internal printer calibration for RGB?

the Z3200 calibrates itself. thus linearization shouldnt be a problem. still the shadows are more blocked when printing from an RGB app then when using a RIP with lin.

but.. the RGB shadow gamut looks wider in 3D.. is that because it contains colors that in the actual print are blocked and therefor not "there" in the RIPs CMYK gamut?

that is my question.. i hope its understandable

[gromit]

but.. the RGB shadow gamut looks wider in 3D.. is that because it contains colors that in the actual print are blocked and therefor not "there" in the RIPs CMYK gamut?

Increased dot gain (namely less L* linearity) can result in 3D plots that are fatter in the shadows (more samples in this area) but not necessarily better shadow detail in the print. You have to look at the distribution, not just the overall gamut shape/volume.

[Ethan Hansen]

ok. thanx for the input about the gamma. i work in ProPhoto with gamma 1.8

Working space gamma has little effect on print performance.

is this also because of the linearization that is better when done by the rip then the internal printer calibration for RGB?

the Z3200 calibrates itself. thus linearization shouldnt be a problem. still the shadows are more blocked when printing from an RGB app then when using a RIP with lin.

I suspect this is the explanation for what you are seeing in print. Many HP printers - I can't say for certain if yours is among them - show differences in output ink limiting when using a rip vs printing in rgb mode.

[MonsterBaby]

"Working space gamma has little effect on print performance."

which is different from what gromit states above about the gamma .. interesting..

[gromit]

Working space gamma has little effect on print performance.

I spend a fair bit of my life opening up shadows in gamma 2.2 (and to a lesser extent 1.8 ) encoded files from people whose monitors have (presumably) been calibrated to show an overly optimistic degree of separation between low values.

[digitaldog]

I spend a fair bit of my life opening up shadows in gamma 2.2 (and to a lesser extent 1.8 ) encoded files from people whose monitors have (presumably) been calibrated to show an overly optimistic degree of separation between low values.

The key word here is presumably (in terms of calibration). I’m with Ethan. The working space gamma has little effect on print performance among other things. .

[gromit]

The key word here is presumably (in terms of calibration).

One only has to read people's posts here on the minimum value in which they can see (bogus) separation on monitors calibrated to 2.2.

[digitaldog]

One only has to read people's posts here on the minimum value in which they can see (bogus) separation on monitors calibrated to 2.2.

That say nothing to the quality of their display calibration does it?

[Ernst Dinkla]

ok. thanx for the input about the gamma. i work in ProPhoto with gamma 1.8

but i like to come back to my original comparising question.

i would like to know why the gamuts of the profiles look different.

is this also because of the linearization that is better when done by the rip then the internal printer calibration for RGB?

the Z3200 calibrates itself. thus linearization shouldnt be a problem. still the shadows are more blocked when printing from an RGB app then when using a RIP with lin.

but.. the RGB shadow gamut looks wider in 3D.. is that because it contains colors that in the actual print are blocked and therefor not "there" in the RIPs CMYK gamut?

that is my question.. i hope its understandable

My suspicion is that the Z3200 calibrated isn't really linear in its output. The Z3100 is linear when calibrated. Based on the differences I see in B&W mode between the two. Calibration is not per definition a linearisation of the channels or delivering linearised total output. For example linearised Light Grey, Grey, PhotoBlack, Matte Black channels do not have to result in a linearised B&W  quad mode output with each channel used proportionally over the total tone range.

There were complaints about the Z3100 gamut compared to the Epson printer gamuts of that time, red especially. The Z3200 got a heavier red and I think a gamma change on the rest of the output. It wouldn't surprise me if there is some overall gain in gamut that way. The gamut of the Z3200 is closer to the Epson gamuts but for B&W I prefer the linearity of the Z3100. How linear Epsons are is another question.

Added: Setting the hue ink limits based on Chroma max or Dmax and then linearising should give different results too. I am not that familiar with RIPs and CMYK profiling. Whether that plays a role for your problem I do not know.


met vriendelijke groeten, Ernst

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[MonsterBaby]

hi ernst, thanks for your reply as well.

my concern is not really the linearity or the gamuts of the colorspaces. altho i find this discussion quite interesting!

i have a Z3100 and Z3200 like you. i realized the same "problem" with my profiles an the Z3100 as well. i always had to open the shadows by editing the profile f.e.

but lookin at the gamut in 3d it looked quite wide... compared to the gamut of the CMYK rip profile.

which delivered a better shadow detailed print though.

so the only thing that i am actually interested in right now is if this theory could be true:

the wider RGB gamut is only "theoratically" there but cannot be displayed on paper because it all "looks" the same.

but the smaller CMYK gamut is indeed smaller BECAUSE the 3d gamut ONLY shows what one can actually see in a print!---

[Ernst Dinkla]

i have a Z3100 and Z3200 like you. i realized the same "problem" with my profiles an the Z3100 as well. i always had to open the shadows by editing the profile f.e.

Printing with the Z3100, HP driver, color mode, application CM used, calibrated, HP's recent firmware and profiles or Z3100 APS custom profiles I do not see a shadow problem.

I doubt that the path to fix your problem is in comparing 3D gamuts etc with prints. If you get better shadow detail and have the impression that the gamuts to your eye are equal then you have your solution. Tried different viewing light output. lumen I mean not color?


met vriendelijke groeten, Ernst


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[MonsterBaby]

oh it is not really about me having a "problem"..

its only about the question about comparing 3d gamut models and their actual output.

because that is what is mostly done when comparing printers.. and if my "theory" is true.. it is not very accurate.