SMART III - Video Calibration Toolkit
Steve Smallcombe's SMARTAVTWEAKS site
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SMART II - Frequently Asked Questions.
What is SMART and can it be used to improve my projector?
How hard is it for a novice to do the SMART calibration?
What are the most common mistakes?
Do I need to have my screen in place and everything all set up before I do the SMART calibration?
What about a gray screen? Will the combination of CC filters and a gray screen make things too dim?
What age (hours) bulb is best to use for SMART or does it make any difference?
Will an ISF calibration performed by a certified ISF technician produce better results than SMART?
Will either the SMART or ISF calibration result in a "dim" picture with the 10HT?
With the 10HT you recommended boosting all the gains to 255. Why not with the 11HT?
I can’t seem to find the IRE 0 field, do I have the wrong version of Avia?
Can SMART be used to correct a red or blue push as measured with Avia?
Will SMART work for my ACME 2000 projector, I don’t see it listed among your supported models?
What about using an Neutral Density filter with the SONY? Isn’t that as good as a CC filter?
Why does one want to add a filter to a projector?
Q What is SMART and can it be used to improve
my projector?
A: SMART software, on its own will do nothing for your projector. However,
if you want to try tweaking your projector by changing the various user
and service mode-based controls, and/or add a colored filter, SMART can
be a big help, as it uses measurements to tell you how you are doing.
It also makes suggestions as to what to do next.
Obtaining the right color balance is an important part of any calibration.
With SMART III, this can be done two ways. The first method is based on
a “known” good factory calibration that SMART will then “memorize”.
For example SONY projectors typically have a fairly well calibrated factory
“low” setting that can be used as a reference calibration.
The second method for color balance calibration, available with SMART
III only, is to use the default value shipped with each meter. These default
value give an independent source of color balance information. Please
read the section on SMART and Absolute Color Balance.
The emphasis with SMART is to get all three colors tracking the same gamma
curve and ideally one representing a gamma of 2.2 - 2.5. It's easy to
see if things roll off at the high end, or if there is too much or too
little red at a given IRE level, etc. Obviously this is much more accurate
than the tweaking by eye method or asking your wife or SO, "Does
this color look better than the last one".
With the SONY 10HT and 11HT, the combination of SMART and CC filters gives
major improvements in contrast ratio and black level. No question about
it. For other projectors, however, the results will vary from one projector
to another. If your projector was very well set up to begin with, there
is not much to gain. There is no magic here. With many projectors however
considerable gains in contrast and grayscale tracking accuracy are possible.
So if you are inclined to tweak, try SMART III. It can make the process
much easier.
Q: How hard is it for a novice to do the SMART calibration?
A: Doing a SMART calibration of a SONY 10HT or 11HT is pretty straight
forward, but can seem a bit scary when you first get started. By the time
you have done your second or third run, it gets easier as the process
will be much more familiar. A SMART run basically consists of setting
up the detector, placing a colored filter in the detector, loading the
Avia disk, and selecting the various IRE windows. For each IRE window,
and for each of the three colors, you will enter a number into the SMART
II spreadsheet. At the end of the run, SMART will tell you what to do
next and/or when you are done.
Q: How long does it take?
A: Once you get used to the process, a SMART run should take about 10
minutes. Typically you will need between 3 and 6 runs to get thing tweaked
properly, including using a CC filter. Thus the SMART process can typically
be done in an evening or afternoon.
Q: What are the most common mistakes?
A: The most common mistakes are covered on
a separate page.
Q: Do I need to have my screen in place and everything all set up before I do the SMART calibration?
A: No. The screen does not really affect the color balance of the projector
since screens are color neutral (including gray screens). Since screens
are also passive that don’t effect gamma tracking or shadow detail
either. SMART uses the light directly from the projector, not the light
from the screen for the calibration.
Q: What about a gray screen? Will the combination of CC filters and a gray screen make things too dim?
A: The first thing to do is to optimize contrast and black levels in the
projector itself using SMART and CC filters. Then it's question of how
much screen gain is necessary to achieve the right balance between black
levels and overall brightness. Gray screens, and gray paint, like ND filters,
are a great idea for projectors like an un-tweaked 10HT with mediocre
black levels, or some of the newer super-bright, projectors (PLV-60) that
put out greater than1000 Lumens.
With Cinema black on and with a CC filter in place, my feeling is that
a white matte screen with no gain is just about right for my 10HT (with
a 102" diagonal). I'm not sure I would want to give up any more brightness
to get even better blacks. A larger screen would push me even farther
away from a gray screen. With the SMART?CC tweaked 11HT, the black levels
and contrast ratios are even better than 10HT.
If you already have your screen, no problem, it is definitely still worth
maximizing the contrast ratio. On the other hand, if you currently have
a screen, try SMART first and then decide whether a new screen it still
needed? Other factors, of course come into play, such as ambient light,
and the gray screen definitely help here.
Q: Once calibrated, does the projector have to
be periodically tweaked? What happens to the SMART calibration as the
bulb ages?
A: Once adjusted using SMART, the projector should not need further tweaking
in the short term. As the bulb ages however, the color balance of the
bulb and therefore the image will change. Since the SMART process will
have memorized the color balance at the time of calibration, SMART can
be used to correct or return the color balance, as the bulb ages, to be
the same as when the projector was new.
Q: What age (hours) bulb is best to use for SMART or
does it make any difference?
A: It is best if the calibration run is done as early in the projector/bulbs
life, as possible as that will best represent the condition of the projector
in the factory when it was color balanced in the first place. If you bulb
has aged more than a few hundred hours then you are probably better off
using the default values supplied with SMART III for the calibration.
Q: Will an ISF calibration performed by a certified
ISF technician produce better results than SMART?
A: SMART for the 10HT and 11HT are specifically designed to get the best
out of these projectors, especially in conjunction with the use of CC
filters. An ISF certified technician may or may not be familiar with these
models and are almost likely not familiar with CC filter tweaks, as that
is not part of ISF training. If you can find as ISF tech willing to calibrate
with the correct filter in place, that should work fine, but will be considerably
more expensive than doing a SMART calibration yourself. Plus as the bulb
ages, SMART can help compensate for the inevitable color changes
Q: Will either the SMART or ISF calibration result in
a "dim" picture with the 10HT, I understand that this is the
result when ISF is done on a CRT?
A: With CRT’s the one must carefully adjust (lower) the contrast
to avoid blooming and phosphor burn-in. These are not issues with LCD
based projectors. The SMART process assures maximum light out of the projector
at IRE 100 while keeping gamma and grayscale tracking accurate at the
lower IRE levels. The use of CC filters will cause some loss of light
output, about 10 to 15 percent, but that is generally not a problem considering
the improved contrast ratio and black levels.
Q: With the 10HT you recommended boosting all the gains to 255. Why not with the 11HT?
A: The gain to 255 thing is an interesting question, and with 10HT the
mantra was "max the gains for maximum contrast". You might think
however, that you should be able to get the contrast ratio at lower gain
settings, but with a higher contrast setting. When you think about it,
raising the gain for a certain color, or raising the contrast should have
a similar effect. Both will increase the light output for that color,
until some maximum light output is reached, i.e., when that panel fully
driven. You can think of the drive level for the panel as the product
of the contrast setting and the gain setting for that color. It does not
matter what combination of gains and contrast settings produces that maximum
output. The max is the max. The best contrast ratio for a projector will
occur when all three colors max at the same contrast setting, and one
is sitting at or just below this point. (CC filters can be essential in
achieving this while at the same time maintaining the proper color balance.)
So when I was setting up my 11HT, I carefully tested two situations, one
with the gains maxed and the contrast lower, the second with lower gains
(equal to the factory red gain in low) and a higher contrast setting.
In both cases, the SMART detector was used to assure that the contrast
setting was right on the edge, i.e. a higher number did not produce more
light, but a lower number did. The result of the measurements was that
the maximum light output was the same for the two cases, and the gamma
tracking below this point was the same as well. So it seems that with
the 11HT at least, there is no point in bumping the gains to 255 as long
as the contrast setting is correct.
Q: I can’t seem to find the IRE 0 field, do I have the wrong version of Avia?
A: On the Avia disk there are both IRE windows and IRE fields. It is essential
that you use the windows and there is one labeled IRE 0. When you show
it with subtitles on, it is labeled black. The IRE fields start at IRE
10, but you should not use the fields as they SONY reacts differently
when it sees a full screen of high IRE values, and this can mess up the
calibration.
Q; Can SMART be used to correct a red or blue push
as measured with Avia?
A: There are lots of useful tests on the Avia test disk, some of which
can be used to make adjustments, other are simply there to test the quality
of various aspects of the display system. The color decoder test on the
Avia disk is the one where one can measure red push. It is testing the
accuracy of the color decoder in determining the saturation of the various
colors with given input signals.
This is different from color balance, which is a measure of the ratios
of red, green and blue with a white signal or various shades of gray.
When one measures grayscale tracking, and tweaks the various user and
service mode controls that we all know and love, one is trying to make
sure that this ratio is right, and does not change with IRE level. When
we add colored filters we make adjustments to these same controls to restore
this color balance.
So color balance is about making white and grays having the right amount
of red or green in the white and gray parts of the image. Too much red,
and the whites look red, etc. Unfortunately to get this tracking right
typically requires instrumentation and measurements, such as provided
by SMART or ColorFacts or an ISF tech, etc.
The color decoder test that might indicate a +20 red push, tests something
quite different. In this test we are using, for instance, a red filter,
so that we can only see the red in the image. We are then asked to compare
the amount of red in a series of red squares with the a gray part of the
same image and judge which one matches. This has nothing to do with the
red vs green ratio, as one is only seeing red, but rather how accurately
the color decoder decodes the red part of the image in the presence and
absence of the other colors.
Unfortunately, errors shown by this test, e.g. a 20% red push is not correctable
on most projectors. So this test may be good for evaluating a potential
new projector, but is of no use in tweaking, and certainly cannot be used
to set the balance between the various colors. What doesn't work is to
back down the red level in response to a red push as this would now screw
up the red balance in the white and gray parts of the image. That would
be even worse.
Q: Will SMART work for my ACME 2000 projector, I don’t see it listed among your supported models?
A: One can use SMART to measure the light and color intensities of any
projector. There are two issues that make SMART projector specific however.
One is a suitable reference color temperature. The second is projector
specific advice. If you are happy with the overall color balance of your
projector, but want to try tweaking the gamma tracking or improve the
contrast ratio, or perhaps try a CC filter, then SMART can certainly help.
What you will need to do however is translate from “raise the red
gain by 10%” to whatever control on your ACME 2000 is used to set
the overall color level for red. It’s not too bad, and if you are
going to tweak anyway, then SMART can certainly make the process much
more objective.
Q: I understand that the SMART calibration is based on the projector. How can you calibrate a projector when SMART does not know about absolute color temperature or color balance?
A: Please read the section on SMART and Absolute
Color Balance.
Q: SMART recommends a CC40R filter, but I want to use a 30R so I wont lose too much light. Is this a good idea?
A: If you measure the loss of red light through a CC30R and a CC40R filter
it is essentially the same, e.g. ~15%, and probably largely due to losses
from reflections. Of course, blue and green are more strongly attenuated
with the CC Red filters and with the 40 more than the 30. When using SMART
however, you are asked, based on the measurements, to increase the gain
for the blue and green colors to restore color balance and compensate
for the blue and green light loss due to the filter characteristics. So
the key is to chose the right filter for the projector, the one that corrects
the lamps color imbalance and ideally allows all LCD panels to be driven
equally. That is the only way to get the maximum contrast ratio possible.
With the 11HT, the 40R is the most common filter, and when appropriate,
it will cause no more light loss than a 30R on that same projector, as
the additional 10% attenuation of the blue and green light will be compensated
for by 10% more light coming through the blue and green panels. For other
projectors, a 30R will be a better match, or one can "overcorrect"
with a 40R and get additional black level improvement, but, in this case,
with some additional loss of brightness.
Q: What about using an Neutral Density filter with the SONY? Isn’t that as good as a CC filter?
A: I used to use a ND filter and believe me the effect of the CC filters
is quite different and significantly better. With ND filters the contrast
ratio is not improved since both the high and IRE 0 light levels are equally
attenuated, say by a factor of 2. One does see a factor of 2 improvement
in black level, but at the cost of a loss of a factor of 2 in overall
image brightness.
The situation is different with the CC filters when they are used in conjunction
with proportional changes in the LCD drive levels. In this case one can
boost the blue and green levels to largely compensate for the blue/green
attenuation of the filter. The key to understanding the improvement in
contrast and black level with CC filters is that the black level is determined
by light leaking through the LCD panels, (or internal reflections). This
leakage level does NOT increase with increased panel drive levels. Now
the factor of 2 attenuation of blue and green by the CC filter at IRE
0 is fully manifest on the screen leading to a factor of 2 improvement
if black level and contrast.
You might think that this process might mess up the color balance at low
IRE levels, but in practice it can actually help. Keeping with the LCD
example for a moment, if the polarization plates for all three colors
are all equally properly adjusted, one would then expect the color temperature
at IRE 0 to reflect that of the source, i.e missing some red. Since the
CC filter is chosen to compensate for the bulbs red shortcomings, this
same CC filter can help correct the low level color temperatures as well.
For those who doubt that this is real, the many SONY users have very successfully
used CC filters to improve black level and contrast ratio. Bill Cushman
is one of these people. Bill has recently reviewed the SONY11HT for Widescreen
Review, Issue 56, which should now be on the newsstands. The essence of
the review is very positive. For me however, one of the more significant
things was that Bill based the review on, and did virtually all of his
viewing with, an 11HT optimized with a CC40 filter! Clearly his review
is a very enthusiastic affirmation of the validity of the CC filters idea.
Q: Why does one want to add a filter to a projector?
A: There are several reasons why someone might add a filter to a video projector, and it is important to understand the various techniques, objectives and results achieved.. While this has been well discussed in several very informative threads on this forum, there seems to be some confusion and questions about how filters are used in various posts, so I thought I would try and post a bit of a summary.
There all basically three filter-based techniques can be summarized as
follows:
Add a colored filter to change the color of the image.
Add a colored filter and change the color settings to compensate
Add a Neutral Density filter.
The first technique uses a colored filter to change the color balance
of the image. This is probably the most obvious use of colored filters,
but various user or service controls can also easily accomplish changes
in color balance. For instance, if the image is a bit too cool, then adding
a warm filter, such as an FLD, will slightly decrease the blue and green
light, relative to red, and give a warmer image, i.e. a lower color temperature.
Such use of a colored filter does not improve the contrast ratio as the
filter will attenuate the light at all IRE levels equally. Since light
intensity is lost in the filter, there will be some loss of overall light
level and therefore a somewhat better black level.
The objective in the second technique is quite different. Here the objective
is to NOT change the color of the image, while at the same time achieving
significant improvements in contrast ratios and black levels.
For instance, with the SONY 10HT and 11HT, the color balance is very accurate
in the factory low mode. It doesn't need to be corrected. So adding a
red colored filter will clearly make the image too red. If at the same
time, you add the filter, however you also boost the blue and green gain
levels by an appropriate amount, you can restore color balance and overall
light level (largely). Since the filter also attenuates the leakage light
that limits the black level and contrast ratio, one can gain significantly
in these areas.
This filter with compensating gain changes approach will not work with
every type of projector. It really only works to the extent that the projector
has a light source that is limited in one color relative to the other.
The UHP bulbs common in many projectors today are deficient in red relative
to the desired D65 reference, and in these cases the CC red filters work
very well. Perhaps rather than thinking of the light source as deficient
in red, it is best to think of the light source as having extra green
and blue that one can use in conjunction with a CC filter tweak!
Since we are compensating for the filter by changes in the gain settings,
we can now in some cases use mush "stronger" filters. For the
SONY 10HT and 11HT either a CC30R or 40R gives the best improvements while
maintaining color balance over a wide IRE range. An FLD or a CC20R "work"
with the SONYs, but do not give nearly as much improvement. (With the
SHARP 9000, they may be about right.)While it is easy to think of the
filter as the "tweak", in this case the methodology used to
measure and restore color balance, (SMART) is also an important.
The third technique is to attenuate the overall light level of the projector,
with the objective of getting better perceived black levels. Here one
uses Neutral Density, or ND filters that attenuate all colors equally.
An ND filter also attenuated all IRE levels equally so the actual contrast
ratio is not really improved. For very bright projectors, an ND filter
can be helpful in improving the perceived black level. Gray screens have
a similar effect, but have the added bonus of also graying or attenuating
ambient light. (ND filters are cheaper and can be easily added or removed
as necessary.)
If your projector has a balanced light source, and you wish to improve
black levels, then an ND filter (or a gray screen) is likely a better
choice than a colored filter, as it maintains proper color balance. There
is however an unavoidable loss in overall image brightness in this case
and the cure may be worse than the disease.
In getting the most out of a projector, in my opinion, the most important
thing to do is maximize the contrast ratio. Once that is done, you can
decide about absolute light levels. Do you want to use a gray screen or
ND filter to decrease the light level and improve the black level, or
do you want to use a screen with gain that puts more of the light back
at the user? This will very much depend on the light output of the projector,
the size of the screen, the room, and to a very large extent, personal
taste.
There is no one right answer. An ND filter may be appropriate for a Sanyo
PLV-60 on a modest size screen, but a for a Sharp 9000, that has about
one fourth the light output, an ND filter or a large gray screen is probably
not a good an idea.
Introduction to how SMART works
Frequently Asked Questions about SMART
Here is what's new is SMART III version 1.2
The Dummies Guide explains the SMART process in a non-technical way
Buy SMART III at EnhancedHT - your exclusive source for all SMART products
Having trouble? Learn the most common mistakes people make using SMART
Read about using bias lights to improve perceived black levels.
Here are some additional tips for the SONY projectors and solution to common problems.
