[Tig] Opinions on the JVC DT-V24L1D?

[Dave Corbitt]

Well, I am certainly not an unbiased bystander but I do have some 
suggestions on what to look for when evaluating any display device no 
matter what the technology used (CRT, LCD, Plasma, DLP, LCOS, SXRD, 
etc.). There are published standards that high end display devices must 
meet to be serious contenders in our business.

1.	Colorimetry is critical. I don't mean by this that you must only get 
the grey scale to accurately track 6500K. Grey scale tracking is 
important but in addition, the ability to correctly reproduce the 
primary colors of whatever imaging system you work in are very very 
critical. This might seem obvious to some but apparently is not being 
considered by others or is misunderstood. For most of us on this list 
working in SD or HD video, REC 709 color space is the one you want. For 
DI work, you will want a larger gamut capability but you must have the 
ability to use LUTs to emulate whatever colorspace you deem appropriate 
for your work including custom ones created to match film outs. Back to 
REC 709. SMPTE C and EBU color space are both very close to REC 709 and 
for most purposes in a modern post production facility, REC 709 should 
be the default for all current work. Now you ask, what is REC 709 and 
how do I know if I have it? If you have an accurate color measuring 
device such as a photo-spectral radiometer or a suitable color anylyzer 
with true CIE standard observer RGB curves, you can measure your 
primaries as CIE values and chart them relative to the REC 709 
standards. If you want to know more about REC 709, do a search for 
ITU-R BT.709, the full title for this colorspace standard. There are 
lots of tutorials on line for colorspace. Charles Poynton is a 
particularly good source of detailed info on all this. If your 
primaries are incorrect, nothing you do will be reliable or accurate 
when viewed on a correct monitor. Some new technology monitors are 
seriously non-standard in this area, some are very good so Buyer 
Beware!!

2.	Gamma Curve is critical. Textbook correct gamma for a television 
device is normally quoted as being 2.22. However, most of us have been 
using Sony BVM monitors for at least the past decade and these will 
typically have a display gamma of approximately 2.40 to 2.50. The 
higher the gamma number, the more the monitor will appear to compress 
the dark end of the grey scale and stretch the bright end. If you want 
a new monitor to make things look the way they do on your old Sony CRT 
monitor, you need to have a monitor with a display gamma close to what 
Sony had delivered. If you have a textbook correct monitor with a gamma 
of 2.22, the images will look flat with darks appearing too open and 
flesh tones a bit too bright. And we all know what the clients will 
say!

3.	Black levels are critical. Some new technology devices will give 
black levels that are not as deep as the best of the old CRT monitors. 
Black levels are vital to conveying mood and depth in a flat two 
dimensional image. The better LCD monitors all have dark filter glass 
screens to bring the overall light output down and in particular to 
bring down the black levels to make them more like a CRT. Bear in mind, 
each manufacturer has different philosophies on how to do this so 
compare carefully. A very sensitive light measuring device will give 
you numbers to compare on this. A properly designed filter glass does 
not change the colorimetry, just the overall light output. It is a 
newutral density filter and thus effects all wavelengths of light 
equallly so no change in the CIE readings for RGB should occur.

4.	Resolution!!! Surprise!!!  CRT monitors were never capable of 
displaying all the pixel detail of an HD signal. The construction of 
the phospor stripes in a Trinitron were never small enough to show the 
finest details in the signal, plus the electron beam tends to defocus 
in highlights making the situation worse. New technology screens tend 
to have discrete pixels that are addressed individually so if your 
screen has 1920 x 1080 pixels in its construction, every pixel in a 
1080 HD signal will be displayed discretely. Some new technology 
screens are not true 1080 resolution but something less such as 1366 x 
768. A 1920 x 1080 signal on that screen would have to interpolated and 
down rezzed to scale to the lower resolution screen structure. If you 
truly want to see every pixel, make sure the screen you evaluate has 
the native resolution you need.

There are other things to consider too but I think I've used enough 
bandwidth for now. Maybe later I'll come back and discuss refresh 
rates, interlace vs progressive, scaling for SD, etc.

Disclaimer:  I market Vutrix LCD monitors for FrontNICHE so have a 
strong interest in what gets said about display devices.

Dave Corbitt
FrontNICHE NA
Summit, NJ 07901
email  DCorbitt77 at comcast.net