Re: HP Dreamcolor uniformity issues
Re: HP Dreamcolor uniformity issues
- Subject: Re: HP Dreamcolor uniformity issues
- From: Richard Wagner <email@hidden>
- Date: Fri, 13 Mar 2009 20:27:27 -0700
On Mar 13, 2009, Tom Lianza wrote:
I thought that I should chime in here because this discussion is
getting out
of hand. First the type of issues being reported here are the
result of
differences on the order of 2-4 delta E. This at least a factor of
three
times less than most CRT monitors and more importantly this
probably better
than the color drift error on most color sensors used in imaging.
I can't speak for others, but the problems I had with the first panel
were way beyond what you describe. The monitor was very clearly
defective, and it didn't take a color scientist or instruments to
figure it out. We have two Artisans and an Eizo CG210. The obvious
color casts and loss of luminance in one corner of the HP were orders
of magnitude larger than we ever experienced on the other monitors,
and it was not possible to accurately color-correct images on the
defective HP monitor. You could slide an image around on the display
and literally watch the color change. I would have been better off
with the cheapo display on our Dell office computer. It was
startling to see, and had HP not replaced the unit with a panel that
did not have this problem, I would not have kept the DreamColor, as
it was simply not up to par, and the defects were not subtle.
If you take one of these monitors, fill the field with a white
image and
stare at it, you will actually see the field change as you stare at
it.
That's simply a function of real, but small changes in the field
and product
of our adaptation. When viewing the full screen gray you are
viewing an
extended field. For large fields, one would use the 10 degree color
matching functions which are quite different than the 2 degree
observer.
When you put an image on that display, you are using a different
mode for
evaluation and you will not really see 2-4 delta E difference under
the
image. You can perform extremely critical color evaluations on the
display
because you are using local adaptation as you are making the
adjustment.
That's all fine for a properly functioning display, but the defective
display had a distinctive magenta side and green side that could be
seen at a glance from 10 feet away. The "staring" was from
disbelief. Likewise, the luminance drop in one corner made
evaluating images on that side of the display impossible, regardless
of the cast.
When you consider the display's ability to handle gradients,
display a wide
gamut, and have a wider dynamic range than nearly any other display
on the
market, a small amount of lack of homogeneity is not an overwhelming
problem.
I agree - but the key is "small lack of homogeneity." The defective
panel - at least in my case - had a large lack of homogeneity. Our
current display is excellent in this regard.
Once you actually use one and compare the display to the printed
page, in a properly color managed environment, you will be pleasantly
surprised.
With a defective unit, it is a dreadful display. With a good unit,
this is truly an awesome display, and image to print matching has
taken a major step forward. As I stated earlier, we're very pleased
with the DreamColor display that we have now, and it's definitely the
favored monitor around here. Although no one has mentioned it, the
construction of the display is also very solid. In fact, the add-on
hood may be bullet-proof. My only gripe with the hood is that it
needs anti-reflective black felt on inside to eliminate reflections
from the plastic, but that was easy to do with felt and spray-
adhesive. I do hope that HP will overcome what are obviously
production issues, because in all other respects the monitor is a
major advance in technology, and it's a joy to use.
--Rich Wagner
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