[Leica] Some Comments on LCD technologies

[philippe.orlent at pandora.be (Philippe Orlent)]

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
> 
> 
> 
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