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Discussion Starter · #1 ·
I had a few questions about calibration of the 7200's color decoder, and thought it may be best to start a thread focused on calibrating and tweaking the 7200.


Please feel free to ask your calibration questions here, and also use this thread to post your results and findings when calibrating.


For starters, I have a question about the color setting adjustment. What is the difference between the color Gain and Offset settings?


For example, when is it appropriate to raise/lower a particular color's gain, vs. raise/lower a paritcular colors offset?


I spent some time today tweaking the 7200 with Mark Haflich using Avia. First things first - we set the contrast and brightness according to the moving needle test and black bar test. I loved this particular calibration because it is not subjective. You really can find an exact point where one click in either direction moves the pattern outside of its sweet/correct setting.


Mark and I both agreed that for his particular set up, the contrast was set perfectly at 44, with the brightness set perfectly at 58. We then double checked the contrast after setting the brightness, and confirmed that in fact it did not move on us - 44 and 58 were the winning numbers.


Next onto the color. According to the color bars we needed to drop the color setting a bit to 44 (from the default of 50) for what we both agreed was the best point where the saturation bars had the lowest rate of flicker in the pattern test. The left hand bar was almost not flickering at all, while the right hand saturation bar was still flickering some. Couldn't really find a balance there. Also no matter how low or high we made the color setting, we couldn't get the smaller rectangles at the bottom of the 4 color bars to match the bars exactly. Any one know why this is, and what the best thing to shoot for is when using this pattern as far as what to match? Do you favor the slow flicker rate in the patter or the color matching, etc?


One thing I did not like about this particular calibration step is that it is quite subjective as to where the best point is, unlike the brightness and contrast settings.


Next onto the color decoder test. Again, this is even more so subjective then the color test. It was good however that we were able to work on it and take turns with the colored filters to find the points we agreed were the best.


We found that the red was measuring close to about a +5% gain. Green and Blue were quite close to 0%. G and B probably could have used a *tiny* bit of correction one way or another, but not enough to worry about at this point anyway.


We lowered the red down to about 45. However Mark pointed out at this point that the blacks seemed to have turned a tiny bit blue on us. To play things safe, since the decoder tests are so subjective, we decided to put the red gain back to the default of 50.


Then we eye-balled some of the advanced test patterns that had lots of gray scales. Mark pointed out the slight red push which could be seen in the greys, and I concurred. At this point I dropped the Red Gain down just a tad to 48, at which point the red push disappeared from the greyscale completely. We proceeded to look at various grayscale patterns, and they simply looked incredible at this point. Very sharp, defined, and in perfect steps of grey (to our eyes anyway).


Ok, so after hours of tweaking it was finally time to go back and see what things looked like. At this point I fired up LOTR. I immediately noticed that the picture had lost some of its punch. It was just a tad washed out at this point. So I bumped the color setting from 44 to 47 just by eye, and much of the vividness came back to the picture. Still not quite as punchy as the out-of-the-box setting, but those settings are probably a tad hot to begin with.


I'd love to write more about how the picture looked, but after all the time spent calibrating it I had to head home to the family. In short I can say WOW, yes, its that good but a few things need to be addressed (and are being as I understand it). I'll be back soon for more tweaks and a detailed report will follow.


This was one main source of questions - we weren't sure what the difference between the Red Gain was Vs. Red Offset, and which we should have been adjusting here. Any advise?


Also regarding the gamma settings - by default I noticed that Video was selected. Is that the best gamma to use in general for watching DVDs and HDTV? When is it appropriate to use the Film gamma?


All these tests were performed in low power mode, as I preferred the slight increase in CR I perceived in that mode. However it was interesting to not that switching between low and high power had no effect whatsoever on our contrast and brightness settings - in both modes the perfect settings (again, based on Mark's setup and sources, etc) were 44 and 58 respectively.


Also I noticed in many cases when I hit the up button once, a setting would jump by two - for example color would go from 45 to 47. No matter how quick I tried to be to increment by one, it would skip by two by certain numbers. Anyone know how to get around this?
 

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lovingdvd,


I spent a few hours in front of the 7200 at abigpicture's place today (I'll post my thoughts in one of the 7200 threads tonight or tomorrow). I ran it through a quick Avia calibration and as I recall, I also came up with 58 as the correct brightness setting. The one thing I noticed is that the adjustments steps seemed to be pretty coarse; in other words, one click up or down made a large degree of difference. WRT the brightness setting, I was surprised at the degree of difference between "58" and the setting one click above it, compared to my 65" RPTV. Did you notice this too?
 

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Discussion Starter · #3 ·
I thought the steps between increments were fairly gradual. I did notice sometimes it was not possible to bump up by one, only two.


I'm not surprise you came up with 58 for the brightness considering that the 7200 I was working on is also on a Firehawk of very similar size (this was a 110", you were on a 106"). Also as I mentioned this is a very concrete and easy to interpret test to perform using Avia. It is good to hear confirmation that you came up with the same exact number.


What did you come up with for contrast and color?


Did you check the color decoder?
 

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to my knowledge as with all projectors and or display devices

GAIN relates to the amount of drive level for the particular color and OFFSET relates to the amount of black or contrast of a particular color.
 

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Discussion Starter · #5 ·
Thanks. So is correct to assume that the color's Gain controls its brightness, and the color's Offset controls its contrast?


In any event, how do you know which control to adjust to dial the best accuracy for the color decoder?


For example, it appeared that I could have remove the red push by dropping the red gain, or dropping the red offset, or some of both. So how does one know how to use these controls. Are these controls helpful only with light meters and related instruments?
 

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Discussion Starter · #6 ·
Anyone know which settings you're supposed to use for this pj's Sharpness control, and where the setting is in the menu. It may have been there, but I didn't see a setting labled Sharpness. In any event according to the pattern it looked right-on.
 

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Lovingdvd,


I think that it may be the other way around, although I am no expert. I think the colours Gain is at the bright end if the scale - probably at about 70 -80 IRE and the offset probably controls the other end - the 20IRE area. Settings are always a compromise - I have a Sony 400Q and it's never perfect but nearly......There is always more tweaking, and more....and more...
 

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Quote:
What did you come up with for contrast and color?
Don't remember.

Quote:
Did you check the color decoder?
No.
 

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Has anyone come up with actual contrast and brightness readings? I'm curious as to how close the 7200 comes to its published specs (1400:1 and 1000 lumens respectively).


Thanks.


htome
 

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Color offset should be used first to correct colors near black. Color gain should then be used to correct colors near white. If you wanted to calibrate with a color meter, you could use color offset to set the proper color of a 10 IRE gray field, then use color gain to set the proper color for a 75 IRE gray field.


"Offset" is the same control as "Brightness," but only acts on a single color.

"Gain" is the same control as "Contrast," but again only acts on a single color.
 

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Quote:
Originally posted by Scott-C
I spent a few hours in front of the 7200 at abigpicture's place today (I'll post my thoughts in one of the 7200 threads tonight or tomorrow). I ran it through a quick Avia calibration and as I recall, I also came up with 58 as the correct brightness setting. The one thing I noticed is that the adjustments steps seemed to be pretty coarse; in other words, one click up or down made a large degree of difference. WRT the brightness setting, I was surprised at the degree of difference between "58" and the setting one click above it, compared to my 65" RPTV.
A setting of 58 tells me that the DVD player was using 0 IRE as its black level. "50" was calibrated using a standard NTSC signal, which has 7.5 IRE as black. In practice, using 0 IRE for black is not a problem provided you set the brightness level correctly; otherwise the dark areas of the picture will look crushed (things that are supposed to be dark will instead be black).


The brightness steps were originally developed for our business models of projectors. The coarsness was necessary so that people would not have to wait too long to adjust the full range. We are changing this in an upcoming firmware release for the 7200 so that the steps are much finer.
 

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As others have indicated use the gain control like a contrast for that color. You will set gains to get the color balance right for white and grays at the highest IRE levels. The offset is like brightness for a color and can, in theory, be used to correct a color problem at the lowest IRE levels, e.g a blue-green cast to the shadows. In practice, however, with fixed panel projectors, the color at the lowest IRE levels, e.g. black, is often dominated by leakage of light through or around the control mechanisms. So obviously the controls have little effect on this leakage light. One can raise the offset level of the non-leaking colors to correct the color balance, but then one loses contrast ratio. The use of colored filters are another answer the leakage light problem.


What you do not want to do is to use either gain or offset setting to correct color cecoder problems that show up in the Color Decoder test. Getting the color of white and gray right is what these controls are all about, not correcting color decoder errors. I tried to explain this my reviews. There are a couple of other good threads on this subject as well, and in the past, Guy Kuo has written very clearly about the difference between color balance for grayscale tracking and Color Decoder errors.
 

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Quote:
Originally posted by Steve Smallcombe
...In practice, however, with fixed panel projectors, the color at the lowest IRE levels, e.g. black, is often dominated by leakage of light through or around the control mechanisms. So obviously the controls have little effect on this leakage light. One can raise the offset level of the non-leaking colors to correct the color balance, but then one loses contrast ratio. The use of colored filters are another answer the leakage light problem....
This is why with the ScreenPlay 7200, we decided to make the color of black (that light leakage you speak of) the same as the color of white. From a design standpoint, this is very difficult with 3-path projectors, but relatively easy (provided you give up lumens) with color sequential systems as the size of each color segment can be varied to balance the colors properly. The color of both black and white in the 7200 are as close as one can practically get to D65, which is a claim few digital projectors can make (without seriously compromising contrast).
 

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Quote:
A setting of 58 tells me that the DVD player was using 0 IRE as its black level. "50" was calibrated using a standard NTSC signal, which has 7.5 IRE as black. In practice, using 0 IRE for black is not a problem provided you set the brightness level correctly; otherwise the dark areas of the picture will look crushed (things that are supposed to be dark will instead be black).
Bob, thanks for the info. Based on this, is it accurate to assume that having the DVD player (it was a Panny RP-56) set to 0 IRE and using 58 as the brightness setting on the 7200 will yield exactly the same results (read: picture quality/black level shadow detail) as setting the DVD player to 7.5 IRE and using a brightness setting of 50 on the 7200?

Quote:
The brightness steps were originally developed for our business models of projectors. The coarsness was necessary so that people would not have to wait too long to adjust the full range. We are changing this in an upcoming firmware release for the 7200 so that the steps are much finer.
Thanks for the info Bob. InFocus seems really committed to making the 7200 as good a home theater projector as it can. Keep up the good work and thanks for your efforts to answer so many questions posted on this forum.
 

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Bob

Is that a flash firmware upgrade? Will prior purchasers of the 7200 be able to get that update? Or only new purchases?

Paul
 

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Quote:
Originally posted by Scott-C
Based on this, is it accurate to assume that having the DVD player (it was a Panny RP-56) set to 0 IRE and using 58 as the brightness setting on the 7200 will yield exactly the same results (read: picture quality/black level shadow detail) as setting the DVD player to 7.5 IRE and using a brightness setting of 50 on the 7200?
Yes. The brightness control is done at the very front end of the processing, so there will be no difference for whatever brightness setting is required to set the black level properly.
 

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Originally posted by paulgas
Is that a flash firmware upgrade? Will prior purchasers of the 7200 be able to get that update? Or only new purchases?
It would be a flash upgrade. Everyone will be able to update their projectors with new firmware, which will be downloadable from our web site. The only requirement is that you need to be able to connect the 7200 to a PC with an M1 cable (M1-D or M1-A with USB). These cables are available from our accessories web store, or your dealer can probably do the upgrade as well.
 

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I would like to say that 58 for 0IRE and 50 for 7.5IRE are not that coarse IMO. In other words, 1 click per IRE is not bad. The PLV70 and other Sanyo's are much more abrupt when being changed.


-Mr. Wigggles
 

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I would like to say that 58 for 0IRE and 50 for 7.5IRE are not that coarse IMO. In other words, 1 click per IRE is not bad. The PLV70 and other Sanyo's are much more abrupt when being changed.
You may be right. All I can compare it to at this point is my 65" RPTV which has less coarse adjustment steps. BTW, I'm certainly not complaining about it - it was just something I noticed and I was curious if anyone else noticed it. Not a big deal at all and certainly not a show-stopper. :)
 

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Discussion Starter · #20 ·
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Originally posted by htomei22
Has anyone come up with actual contrast and brightness readings? I'm curious as to how close the 7200 comes to its published specs (1400:1 and 1000 lumens respectively).


Thanks.


htome
I'm very curious about this as well. I heard that the Marantz S2 was measured around 1700 but at a *very* significant cost of lumens.


The 7200's specs are supposedly fair and accurate. So it would be extremely impressive if the pj could be measured at its specs of 1400:1 at 850 lumens.


Bob - have you had a chance to measure this? With the pj fully calibrated and tweaked every ounce of the way, what range would you expect the CR and lumens to be in? Thanks.
 
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