We studied exactly this point during a research project some years ago. we set the (D50) brightness to max cd/m2, it is feeble enough anyway, this corresponds to L* =100. Then we simulated the print by colour management and positioned the print, that exactly corresponded to the print profile, next to the screen. the illumenation of the print was dimmed till the brightness of the paper on the screen matched the "brightness" of the hardcopy paper white. Under these lighting conditions we noticed that not so subtle differences as those between prints on LWC and art paper could no longer be reliably be seen. The human eye needs 200 lx for optimum appraisal. we concluded that softproofing with the current 150 cd/m2 or less is not good enough for high quality appraisal. We would need at least 600 cd/m2 for most observers. Regards Mit freundl. Gru?en Fred Dolezalek Dr. Friedr. Dolezalek FOGRA, Graphic Techn. FOGRA Forschungsges. Research Association Druck e.V. dolezalek at fogra.org Tel. +49-89-43182-311, Fax +49-89-43182-100 PO. Box 80 04 69, D-81604 Muenchen, Germany Streitfeldstr. 19, D-81673 Muenchen, Germany -----Ursprungliche Nachricht----- Von: eci-en-admin(a)lists.transmedia.de [mailto:eci-en-admin@lists.transmedia.de]Im Auftrag von Erik Koldenhof Gesendet: 30. Marz 2004 13:49 An: eci-en(a)lists.transmedia.de Cc: Jo Brunenberg Betreff: [ECI-EN] Monitor calibration and brightness settings (thoughts) Dear group, Recently, one the group members asked me to give my standpoint on maximum monitor brightness settings for calibration. Last year, we performed a study on Apple LCD displays and the calibration with the EyeOne (http://www.colormanagement.nl/acdcolor), and we had to deal with more or less the same question. We came up with the following theoretical thoughts, but actually they seem to work pretty OK in practice as well. I would like to throw these thoughts to this group as well, and hope that some of you can give a standpoint on this. OK, here's our thought. When calibrating a display, measurement are made in CIE-XYZ, and of course the 'Y' value for the whitepoint also states the brightness in Candela (eg 238.00). The monitor profile however always sets the maximum L (CIE-Lab) to L=100, no matter what the actual brightness for the display is set to. Programs like Adobe Photoshop uses the Lab values for there calculation (eg. when doing softproofing on screen), so Photoshop does not know the actual brightness of the display. Therefore, different displays, calibrated at different brightness settings, will always produce another contrast. During our study on the Apple LCD displays, we had to measure Photoshops Softproof color on screen with the SpectroLino, to check the quality of the profiles made by the EyeOne Display. When measuring reflective colors (eg. printed work), there's no need to 'normalise' the XYZ values to CIE-Lab. That's why you can see that a paperwhite has an L value of 96.00 or something like that. Photoshop calculates with that value as well during softproofing. For display profiles, the XYZ measurements are normalised to CIE-Lab (L=100), so your app does not know the actual brightness, as state before. Therefore, your softproof might not be as great as you want it to be. What we finally came up with, is to set the brightness of the monitor (can be measured from ProfileMaker Pro) to about 100Cd/m2. Then, the normalisation form XYZ to Lab is more or less set to zero. The L=100 value in your monitor profile is more or less the same as measured in XYZ ('Y'=100). Whit this monitor profile active, we produced several CMYK colors in Photoshop and performed a softproof which were measured again with the spectrolino. The results were great. Also when looking at the printed material, the visual match was very OK as well. So, in theory our conclusion is to set the monitor brightness to about 100Cd/m2, and in practice it works for us very well. There's of course one thing that we did not answer at this point, and that is the is the illumination of the printed work inside your viewing booth. I'm curious if some of you can add some to this discussion. Colorfull greetings, Erik Koldenhof ------------------------------------------------------------ STARTING MARCH 1st 2004, OUR NEW POSTAL ADRESS IS: Koldenhof Grafimedia Expertise Postbus 1114 2280 CC Rijswijk tel. (+31) 70 336 02 42 fax. (+31) 70 394 11 87 www.koldenhof.nl www.colormanagement.nl e-mail: erik(a)koldenhof.nl ------------------------------------------------------------