Although not as versatile as CRTs,
LCDs are being seen as the preferred display for an
increasing number of applications.
They can produce very bright and sharp images but can also be harder to
properly set up than CRTs.
This article outlines their major pros and cons arranged in order of importance.
For a more detailed discussion see
What Makes a Great LCD
Testing and Evaluating LCDs.
Note: most of the discussion here regarding LCDs also applies
to DLP, Plasma and LCoS displays.
Image is perfectly sharp at the native resolution of the panel.
LCDs using an analog input require careful adjustment of
pixel tracking/phase (see Interference, below).
2. Geometric Distortion
Zero geometric distortion at the native resolution of the panel.
Minor distortion for other resolutions because the images must be rescaled.
High peak intensity produces very bright images.
Best for brightly lit environments.
4. Screen Shape
Screens are perfectly flat.
Thin, with a small footprint.
Consume little electricity and produce little heat.
Principal LCD Disadvantages
Each panel has a fixed pixel resolution format determined at the time
of manufacture that can not be changed.
All other image resolutions require rescaling,
which generally results in significant image degradation,
particularly for fine text and graphics.
For most applications should only be used at the native resolution
of the panel.
If you need fine text and graphics at more than one resolution
do not get an LCD display.
LCDs using an analog input require careful adjustment of pixel tracking/phase
in order to reduce or eliminate digital noise in the image.
Automatic pixel tracking/phase controls seldom produce the optimum setting.
Timing drift and jitter may require frequent readjustments during the day.
For some displays and video boards you may not be able to
entirely eliminate the digital noise.
3. Viewing Angle
Limited viewing angle.
Brightness, contrast, gamma and color mixtures vary with the viewing angle.
Can lead to contrast and color reversal at large angles.
Need to be viewed as close to straight ahead as possible.
4. Black-Level, Contrast and Color Saturation
LCDs have difficulty producing black and very dark grays.
As a result they generally have lower contrast than CRTs and the
color saturation for low intensity colors is also reduced.
Not suitable for use in dimly lit and dark environments.
5. White Saturation
The bright-end of the LCD intensity scale is easily overloaded,
which leads to saturation and compression.
When this happens the maximum brightness occurs before reaching the peak
of the gray-scale or the brightness increases slowly near the maximum.
Requires careful adjustment of the Contrast control.
6. Color and Gray-Scale Accuracy
The internal Gamma and gray-scale of an LCD is very irregular.
Special circuitry attempts to fix it, often with only limited success.
LCDs typically produce fewer than 256 discrete intensity levels.
For some LCDs portions of the gray-scale may be dithered.
Images are pleasing but not accurate because of problems with black-level,
gray-scale and Gamma,
which affects the accuracy of the gray-scale and color mixtures.
Generally not suitable for professional image color balancing.
7. Bad Pixels and Screen Uniformity
LCDs can have many weak or stuck pixels, which are permanently
on or off. Some pixels may be improperly connected to adjoining pixels,
rows or columns.
Also, the panel may not be uniformly illuminated by the backlight resulting
in uneven intensity and shading over the screen.
8. Motion Artifacts
Slow response times and scan rate conversion result in severe motion artifacts
and image degradation for moving or rapidly changing images.
9. Aspect Ratio
LCDs have a fixed resolution and aspect ratio.
For panels with a resolution of 1280x1024 the aspect ratio is 5:4=1.25,
which is noticeably smaller than the 4:3=1.33 aspect ratio for
almost all other standard display modes.
For some applications may require switching to a letterboxed 1280x960,
which has a 4:3 aspect ratio.
Considerably more expensive than comparable CRTs.