ISO 12646 & 3664

[Lars Jacobsen]

Hi,

Softproofing....
For some time I have been using an Eizo ColorEdge CG242W monitor and JUST colorMaster 1 cabinet.
Monitor has been calibrated to 5800K, 120cda and gamma1.8.
Cabinet approx 380lx.
Matching print with ISO 12647-7 proof works fine, but softproofing on a monitor is more diffucult I think.

I have downloaded the Fogra Softproof Handbook and read it a couple of times now and I am now off course even more confused
As Fogra says, "Most likely, the largest uncertainity in prepress is the concept of “gamma“. " I agree with that.
Fogras general recomendations are:
Luminace: 160cda
Temp.: +/- 5800K
Gamma: #1: LStar #2: G1.8

A cabinet with 380lx is kind of dark so I guess that is why the recomendation is now 160cda wich gives about 500lx in cabinet.
Different gamma settings gives very different results.
I guess my question is if anyone can explain in easy words the differences between LStar and gamma1.8 and maybe share how your calibration settings?
Gamma1.8 gives a kind of "light OSX" since it is now based on the more commercial and photgrapher friendly gamma2.2.

[paffen]

Lars: Have you had a look at ugras UDACT-documentation? They try to at least visually explain the difference. Basically L* has better details in the darks than gamma 1.8 and better details in lights than Gamma 2.2.
To further confuse matters, there's also the issue of RGB-profiles, where both sRGB and AdobeRGB has a gamma of 2.2. ugra and FOGRA seem to recommend the usage of ECI RGB 2 as the RGB-working space. However, it is very unclear how we are supposed to get data into ECI RGB as conversion between RGB-spaces is discouraged. I would suggest that your problems with softproofing are related to your RGB workingspacegamma and how the monitor is calibrated in relation to that.

[Lars Jacobsen]

Paffen....
Since november 2009 I have learned a bit more when it comes to gamma and monitor calibration even though the response on this forum was....not there

I know now that no matter what gamma you calibrate your monitor towards every color-managed software will use the internal gamma of the used ICC-profile. This means that the big differences you see in the OS, in videos etc with different gamma settings wont be seen in Photoshop/Indesign etc. This also means that the gamma settings is not that important for us in Prepress. I think one should try to avoid having different gamma for the monitor profile and your working space. This way they "wont work against" each other and cause bad gradients. I guess one can compare it somehow to the what can happen if you have both a big linearization curve (CTP) and TVI curve (Press). If they are both big and work in opposite direction you can get bad gradients.

Since Adobe, Nikon, Canon and the Photo industry wont implement ECIRGBv2 I think the use of this standardized working space will just mean more confusion and work. That is why I calibrate towards gamma 2.2 and use AdobeRGB as working space. This way I get OSX to look the way it was created and get to see what the photographers and most people see on their monitors.

PS: I use 140cda and aprox 380lx in the cabinet these days.

[paffen]

Excellent Lars, then we are in agreement on that too. As the standards-bodies move forward at a glacial speed I think it's up to the industry to find practical approaches to everyday problems. This is a good example of exactly that approach. It would be nice with some kind of site documenting best practices as they evolve and we find better ways to achieve the goals of numerous ISO-standards without working through positively arcane procedures and offical recommendations...