Archived posting to the Leica Users Group, 2005/07/20
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Thanks Tom, Absolutely useful and also very well written for non-techies! Philippe > From: tlianza <tlianza@sequelimaging.com> > Reply-To: Leica Users Group <lug@leica-users.org> > Date: Wed, 20 Jul 2005 09:35:57 -0400 > To: <lug@leica-users.org> > Subject: [Leica] Some Comments on LCD technologies > > Hi to all, > > I noticed some requests for information about LCD panels and I thought that > I would share some of my experience with the group. I've been designing > calibration systems for displays for over 17 years and I have a great deal > of direct interaction with some of the best display manufacturers and their > technology. My team designed the Sony Artisan hardware as well as many > other calibrators that are shipped with displays. We also designed the > Eyeone Display for Gretagmacbeth. > > When you are looking for an LCD panel for critical image viewing, you have > to expect to pay a premium for it. If you are looking at quality panels > you > should be aware of a few acronyms that are hints about the panel quality > and > usability for typical image viewing. Panels that use IPS (typically Apple, > NEC-MITS high end panels), VPA (Samsung), SHA (High end sharp panels) > provide excellent field of view and great stability. To the best of my > knowledge, all the high end Eizo panels utilize IPS technology. A data > sheet > will typically list the technology as TFT/IPS or TFT/VPA. If you only see > TFT, it's a good bet that you are not getting a panel that has high image > quality potential. > > I personally use a Samsung SyncMaster 243T. This is a state of the art > panel, but it cost about $1800 dollars. It is a 24 inch, VPA technology > panel with a resolution of something around 1900X1200 pixels. If you go to > the Dell website and search for 24 inch panels you will find this one and a > cheaper one. The cheaper one has a higher luminance and actually has a > faster response time. The point is that it is a standard TFT panel and > it's > angular field of view, while large, changes rather dramatically, making it > useless for image evaluation activities. That's why the luminance is > higher, it is the difference between looking into a search light verses > looking at a more diffuse surface. The higher quality panels have longer > response times, meaning that they are not really well suited to viewing > movies or gaming. This response time is result of the switching mechanisms > in the panel. That is a fundamental tradeoff in the industry today, fast > response and high on-axis luminance vs a wide field of view and good tone > reproduction. > > The higher luminance of the LCD can be problematic. My LCD luminance is a > factor of three times greater than my CRT. I can't have them both on the > desk at the same time. When used in dim lighting, it can be quite tiring. > For this reason, if you are planning to switch to one of these newer LCD's > you will have to pay a bit more attention to your surround environment, if > you are doing critical color evaluation. This has been the biggest problem > in my workspace. The large surface of the panel is good when working in > photoshop because I set the surround to a neutral on the panel (Full screen > display). > > I have not found color gamut to be a problem. As a color scientist, I'm > well aware of the issue and in my imaging workflow, it's not a problem. If > you are working in Graphic Arts reproduction activities, it may be a > problem. The high absolute luminance causes an observer to see the scene as > more saturated and slightly more contrasty than at lower luminance. The > tone reproduction of these modern displays is quite good. The higher end > displays have much better control of the driving circuits and the display > transfer functions are very close to gamma - law relationships. Cheaper > displays tend to have saturation issues in both the highlights and the > shadows. I designed a rather critical digital test target for displays and > I can say that in both shadow and highlight, the high end LCD displays > often > perform FAR better than any CRT monitor that I have used. I have a Sony > Artisan and it is now sitting in storage. Once I started using this > Samsung > flat panel, the rest of the image quality issues such as noise, flicker and > sharpness just overwhelmed any small contrast ratio issues the monitor > might > have . The fact is that this panel has a 500:1 contrast ratio which > requires no tedious bias adjustment. > > I have to make a note about calibration. Calibration of the low end TFT > panels is very tough. You can't really correct for many panel defects > through calibration. When I calibrate the panel on my PowerBook 15", it > corrects the highlight saturation , shadow clipping, and generates the > correct white point, but at the expense of display luminance and I'm still > faced with a display that has limited viewing angle. If you are a Leica > user you should take the time to test some high end LCD displays from > companies like Eizo, Sony, NEC, Mits, Samsung and Lacie. I would avoid the > 19inch formats because there is a lot of cheap technology in expensive > cases... Stick to 20 inches and above and look closely at those specs. > Bring > a cd with some images to a store and view the images. Unfortunately, you > are not going to see many of the high end displays at Best buy or Circuit > City. You will see them at PMA and CES and other tradeshows. > > Take care and take good pictures ! > > Tom Lianza > Director of Display and Capture Technologies > GretagMacbeth LLC > 3 Industrial Drive > Unit 7&8 > Windham, NH 03087 > 603.681.0315 x232 Tel > 603.681.0316 Fax > > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >