TFT Display Evaluation Notes
|PCstats TFT Display Evaluation
evaluate the quality of TFT displays with the help of a program called
Nokia Monitor Test. The software application displays a range of colours
and test patterns that can help diagnose just about any visual problems or
defects a TFT display may contain.
It can also be a very useful tool for
properly adjusting a display to the optimal settings. The software
consists of eleven tests which can be run in steps as adjustments are made
to the OSD. As the tests are run we look for the following problems, only
one of which should be inoperable (broken pixel).
Broken Pixels: What we class as a 'broken pixel' can
fall under any one of the following circumstances: Pixel always on (any
colour), pixel always off, pixel unable to display a shade (red, green,
blue, black, white), pixel shown colour gradient.
Pixel Clock: If the number of dot clocks within one
horizontal synch are not properly configured the screen will appear to
drift or vertical stripes may be generated. This should be correctable by
the on screen menu.
Phase: If the phase of the display data and dot clock
are not correctly tuned the screen can flicker, or text be displayed
blurry. For example text may appear dithered, or when looking at a test
pattern of a one-pixel black, one-pixel white checkerboard pattern the
pattern may be distorted. This should be correctable by the on screen
Response Time: We look for any streaking associated
with moving a full page of text up or down quickly. Displays with slower
refresh rates tend to show some degree of image streaking or text
discoloration which can be distracting.
Stand Stability: TFT displays are fragile components and the
stand should offer adequately stable support as well as be easily
We deduct marks for quality control if there are any predominant
broken pixels in a display. While many manufacturers may consider a
few broken pixels acceptable, we believe the high cost of TFT displays
should translate into a clear and unblemished image.
|Display Test System
||ATI Radeon 8500 |
Windows 2000 |
||Color Temp: 6500 Kelvin|
|LCD Display Test
||Test Notes and Observations|
Excellent picture geometry at the 152's native 1280x1024
resolution. The image is very sharp.
At 800x600 resolutions the dithering is good, and lines are not overly blurry.
|Brightness and Contrast:
Good shading in the 20% to 100% range. It
is difficult to see major changes in shading in the 1%-4% range, but the
rest of the scale transitions well. There is
some slight luminance around the edges of the panel
(just visible in a dimly lit room) from a head on
view of a pure black screen. This is inline with the variations between
LCD panel to panel and not detrimental.
test screen is brighter than the CRT monitor I am using to write this so readability
in well-lit rooms should remain excellent. Each of the three colour test screens are nice and vivid, and there
are no traces of broken or damaged pixels what we can spot.
The test grids in RGB illustrate the
worst case situations when different coloured pixels must work closely
together, and since they comprise different parts of a pixel they do not line
Excellent at 1024x768. All test patterns are clearly visible and defined in both the
horizontal and vertical axis.
Resolution was also excellent at the native
1280x1024 resolution. Image dithering at lower resolutions offers a
slightly blurry version which is not going to put people off from using
lower screen resolutions to increase font sizes however.
Excellent, all test patterns were displayed properly and without interference, walking
lines, or scatter. Properly adjusting the image sharpness is
critical in this area, as the auto adjust does not always update this
setting under an analog signal.
Other Evaluation Notes:
With a pixel refresh rate of 25ms the 152T is
inline with other LCD offerings making it good for gaming, but not as fast
as a CRT. LCD displays tend to have a better following the office
environment where eyestrain is generally a lot lower. The viewing angles
on this display are a bit short compared to recent 170/170
monitors so we are
going to take that into consideration (especially with the
high degree of tilt). Adjusting the display itself is straight forward and we had
no problems getting it into a comfortable viewing position. Luminance bleed around the
edges of the LCD glass exists in some level on just about every panel we have
reviewed, and the 152T falls in line just the
||*Note: all criteria on this
evaluation sheet are graded as either Pass, Satisfactory, or Fail.|
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