Datacolor User to User Support Group.

I've tried to calibrate my projector (Sanyo PLV-70) today, but this
was a complete disappointment! First of all, the projector calibration
doesn't allow to set the white point correctly. My projector has RGB
controls, but the Spyder2Pro software only offers Kelvin sliders and
Kelvin presets, no RGB adjustments as for monitors. So I used 2.2,
6500K-Native and ran the calibration, but the result was horrible!
Everything was much too green. The colors were so wrong, even a blind
man would have seen it. When switching the "Before" and "After"
pictures at the end of the calibration process, one could see how
horrible the Spyder2Pro chose the colors. I thought "Before" and
"After" should be exchanged - then the result would have been
satisfactory.

By default, my PLV-70 produces a rather greenish picture. I know that,
because I compared it directly to a professionally calibrated PLV-Z4,
which has fantastic colors. The Spyder calibration made the picture of
the PLV-70 even more green, which obviously can not be correct.

All in all I can not recommend projector calibration with Colorvision
products at all. It's a complete waste of your precious time (and the
expensive projector lamp time). It simply doesn't work and the results
are ridiculous!

Regards,

Martin

PS: I'm sure I have set up everything correctly. I've double checked
everything, ran the calibration twice, etc.

>I've tried to calibrate my projector (Sanyo PLV-70) today, but this
>was a complete disappointment! First of all, the projector calibration
>doesn't allow to set the white point correctly. My projector has RGB
>controls, but the Spyder2Pro software only offers Kelvin sliders and
>Kelvin presets, no RGB adjustments as for monitors. So I used 2.2,
>6500K-Native and ran the calibration, but the result was horrible!
>Everything was much too green. The colors were so wrong, even a blind
>man would have seen it. When switching the "Before" and "After"
>pictures at the end of the calibration process, one could see how
>horrible the Spyder2Pro chose the colors. I thought "Before" and
>"After" should be exchanged - then the result would have been
>satisfactory.
>
>By default, my PLV-70 produces a rather greenish picture. I know that,
>because I compared it directly to a professionally calibrated PLV-Z4,
>which has fantastic colors. The Spyder calibration made the picture of
>the PLV-70 even more green, which obviously can not be correct.
>
>All in all I can not recommend projector calibration with Colorvision
>products at all. It's a complete waste of your precious time (and the
>expensive projector lamp time). It simply doesn't work and the results
>are ridiculous!
>
>Regards,
>
>Martin
>
>PS: I'm sure I have set up everything correctly. I've double checked
>everything, ran the calibration twice, etc.

Sorry to hear about these problems, but: have you tried contacting tech
support about this? And perhaps David Tobie will step in today and have
some questions about your setup, and suggestions?

Have you calibrated anything else with that Spyder, such as a Mac or PC
display? If there's a hardware problem and something is wrong with the
instrument, that would certainly explain why it doesn't work.

(I won't be the one to troubleshoot this, but at least we can get the
process started).


Best regards,


-- 
David Miller
Senior Software Developer, Digital Color Solutions
ColorVision

Hi!

First of all, the PLV-70 is a high brightness unit (2000 Ansi Lumens),
so when it projects a white image, the whole room is not dark at all
anymore. The screen reflects so much light, that you can easily read a
newspaper in the room. That's why you can also tell if the white is
greenish, blueish or whatever. So in my opinion, I would make sense to
calibrate the white point - at least you could give the users the
possibility to do so if they wish.

Secondly, my Spyder2Pro hardware seems to be ok - I've successfully
calibrated 4 monitors with it and the results are very good. I always
liked the "After" picture much better than the "Before" one - flesh
tones looked more natural and the overal image appearance was more
pleasing. So "my Toyota is not broken", I should just not try to drive
it somewhere where it's not supposed to be ;-)

I guess the whole projector calibration process is somehow strange. I
can't imagine getting reliable results when the sensor reads light
from its own shadow. And my experience seems to prove that point. The
procedure as suggested by the calibration software is easy to follow
and you can't really do anything wrong. So if it still produces
results that are way off (and the hardware is ok), then either the
software must be buggy or the whole principle of the calibration
process has flaws. I guess it's the latter, otherwise I couldn't
explain why my calibration works for monitors but not for projectors.

Regards,

Martin

PS: I don't any reason to discuss this privately, as suggested by
CDTobie. Of course ColorVision only wants satisifed customers
reporting how great the product is, but a discussion group must also
have room for negative experiences.

> No, that defies the laws of color theory; if you fill a room with
yellow 
> light, the eye adapts, and that yellow light looks white. There must
be some other 
> source before your eye can distinguish.

That can't be correct. It would mean that if I projected a yellow
image (RGB=255,255,0) my eye would adapt to it and it would look white
to me. That's obviously not the case - at least not within a few hours
(maybe if I lived in a yellow world for a few years it would ;-)

Furthermore, I know what the walls and other object in the room look
like and which color they are, so I CAN tell if they are illuminated
by a greenish or blueish light, etc.

Also, if you compare e.g. grey parts of an image with colored areas,
you can tell if the grey tends towards red, green blue, etc.
especially if you can compare different settings directly, which is
the case with the "Before" and "After" images.

> How would you explain the many satisfied projection S2P calibration
users 
> then?
Probably the colors were initially "very bad" and after calibration
just "bad". That's definitely an improvement and since everything is
relative according to your explanation, even a "bad" result can look
quite good. Maybe my PLV-70 is by default pretty good (just a tad on
the green side), so messing with the settings can just make it worse?

> projection. Is the room you are working in pitch black when the
projector is 
> off?
Of course! I have absolute control over the ambient light and I can't
see my hand in front of my face if the projector is off.

> shadow, and the Spyder is reading the whole screen, not some tiny
area in the 
> shadow.
My screen size is about 7 square meters. When the Spyder is placed 30
cm away from the screen, how can it measure the whole 7 m2? It can
only see a tiny fraction of the screen, with the shadow in the middle
covering a significant area! In just this area, there's no direct
light from the projector, just reflected light from the rest of the
room. For me it's clear that this absolutely will influence the
measured values! Hence the reports of people who are setting the
Spyder up in a way that it faces the projector, not the screen...

> ...projection rules, and not allow the eye to white point compensate
to the projected light.

But that's exactly the point! I don't need any calibration if the eye
would compensate to anything anyway. But it doesn't! That's why I want
the white point to be exactly where it should be, not where my eye
maybe moves it over time. The whole point of calibration is to make
the results physically correct and independant of subjective impressions.

Regards,

Martin

> > > No, that defies the laws of color theory; if you fill a room with
> > yellow
> > > light, the eye adapts, and that yellow light looks white. There must
> > be some other
> > > source before your eye can distinguish.
> > 
> > That can't be correct.
> > 
> 
> I guess I will refrain from arguing basic color theory with you, and
refer 
> you to any text on the subject.

Out of curiosity, I tried this yesterday evening: I've projected a
bright yellow image and spent 30 minutes in the room, looking at the
image without any other light source in the room.

And guess what: after that time, the image was still yellow! Maybe my
eyes were a bit less sensitive to yellow, but the color still was
obviously yellow, not white. Must be because my eyes and my brain know
what yellow looks like, so they don't need a direct comparison with a
different color to tell that it is not white. That's pretty logical,
because the brain can learn and remember. Otherwise you'd always need
a dog standing next to a cat to tell which one is the dog!

So you can refer me to any text you like, but this will not change the
personal experience which I can verify anytime. I don't rely on
theoretical papers on the subject as you do, but I try things myself.
This is much more reliable and furthermore it shows me how I
personally experience things, not how it could be in theory.

Also, your whole argumentation about the eye adapting to a white point
is wrong when I watch a movie with the projector. The image is not
always white - it's sometimes mostly green, then red, blue, whatever.
So when the image is white or grey again, you can tell to which color
it's biased, because this bias is not always dominant and so the eye
(or actually the brain) will not filter it out. That's really easy -
try it yourself instead of reading about it and you'll see what I mean.

Regards,

Martin

I like to go camping. My first tent was red. When I awoke to the 
morning sun through the red tent, everything looked OK. When I 
climbed out, my world was cyan for quite a while. For your eyes not 
to adjust to color bias may be a gift in that such a person could 
visually calibrate without instrumentation.:)

--- In colorvision_group@yahoogroups.com, "mhovie71" <martin@...> 
wrote:
>
> 
> > > > No, that defies the laws of color theory; if you fill a room 
with
> > > yellow
> > > > light, the eye adapts, and that yellow light looks white. 
There must
> > > be some other
> > > > source before your eye can distinguish.
> > > 
> > > That can't be correct.
> > > 
> > 
> > I guess I will refrain from arguing basic color theory with you, 
and
> refer 
> > you to any text on the subject.
> 
> Out of curiosity, I tried this yesterday evening: I've projected a
> bright yellow image and spent 30 minutes in the room, looking at 
the
> image without any other light source in the room.
> 
> And guess what: after that time, the image was still yellow! Maybe 
my
> eyes were a bit less sensitive to yellow, but the color still was
> obviously yellow, not white. Must be because my eyes and my brain 
know
> what yellow looks like, so they don't need a direct comparison 
with a
> different color to tell that it is not white. That's pretty 
logical,
> because the brain can learn and remember. Otherwise you'd always 
need
> a dog standing next to a cat to tell which one is the dog!
> 
> So you can refer me to any text you like, but this will not change 
the
> personal experience which I can verify anytime. I don't rely on
> theoretical papers on the subject as you do, but I try things 
myself.
> This is much more reliable and furthermore it shows me how I
> personally experience things, not how it could be in theory.
> 
> Also, your whole argumentation about the eye adapting to a white 
point
> is wrong when I watch a movie with the projector. The image is not
> always white - it's sometimes mostly green, then red, blue, 
whatever.
> So when the image is white or grey again, you can tell to which 
color
> it's biased, because this bias is not always dominant and so the 
eye
> (or actually the brain) will not filter it out. That's really 
easy -
> try it yourself instead of reading about it and you'll see what I 
mean.

> 
> Regards,
> 
> Martin
>