Working with strange/unusual color management system. - AVS Forum
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post #1 of 12 Old 01-05-2013, 08:42 AM - Thread Starter
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Hi,

I have a Sony VPL VW60 with a color management system Sony calls RCP (real color processing.)

It clearly is not a 3 dimensional color management system and after many experiments I left it "off" and just did grey scale and gamma.

I know there are 2 great solutions to a strange color management system...

1) Use an outboard video processor. I know this is a great and fully effective solution. It's just not in my budget.

2) Move to a display with a better color management system. Also great and fully effective and my choice over option 1 but I'm still not there yet.

So,...

Any thoughts or musings about working with wonky/strange color management systems?

This version I'm referring too lets you adjust in 2D space just fine. I can put the gamut exactly on the targets for x and y. But,.. my previous attempts didn't get any lower delta E readings because Y would be further off. This is something I still don't understand fully.

I would think that putting the primaries and secondaries exactly where they need to be in terms of x and y and then still having access to controls to adjust the grey and gamma should result in the ability to "fix" those Y values.... I'm still a bit confused about that.

-Brian
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post #2 of 12 Old 01-05-2013, 09:09 AM
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post #3 of 12 Old 01-10-2013, 12:12 PM
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Can you post some numbers/charts?

How is the luminance of your primary colors?

The hue of the secondaries?
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post #4 of 12 Old 01-10-2013, 01:41 PM - Thread Starter
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I can.

It's just a matter of having an hour or so and not being worn out.

Maybe tomorrow I'll do some tweaking and post examples of what I find.
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post #5 of 12 Old 01-11-2013, 08:08 AM - Thread Starter
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Tried to get some data to back up what I was saying this AM.

The session started great but eventually I was looking at too much data and making changes too quickly.

My projector has a lot of enhancement circuitry and most of it is best dis-abled.

For example... Dynamic Iris. This can greatly enhance the black level but it dims the white ( in my experience) and thows the gamut for a curve as well. Plus it makes the luminance graph a bit bumpy.

I could spin my wheels and go in circles with setup and I often do.

Anyways,... What I found today was what I thought.... The RCP (Real Color Processing) can put the primaries and secondaries exactly on the xy positions of the CIE chart but doing so thows off the Y or brightness of the colors badly. Delta Es went up even though Delta XY was generally .004 or so.

I have some data so I may be able to post up more information but eventually today I went back to leaving RCP off which is what I usually do. The colors look natural and they are much closer in terms of brightness when I leave the RCP off.

If I had a truly 3D color processing circuit then I could improve things. I will certainly look for that in my next display.

-Brian
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post #6 of 12 Old 01-12-2013, 10:32 PM
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Auto iris is perfectly fine to use... opening and closing the iris should not affect gamut at all unless the projector is very strange. You NEVER should have Auto Iris activated when you calibrate a projector. If you are going to use Auto Iris (I like it quite a lot, especially Sony's implementation which is very very difficult to detect in operation... you might notice it 1 or 2 times during an average movie), when you calibrate, you should use a fixed iris opening in the middle of the range (roughly half-way between fully open and fully closed. When you are done calibrating, turn Auto Iris on and forget about it and enjoy your images. Auto Iris (especially Sony's implementation) closes the iris for darker scenes and opens the iris for lighter scenes. It will NOT make brighter scenes less bright unless you are using the "limited" version of Auto Iris present on some Sony models... the "limited" mode never fully closes nor never fully opens the iris. That could look dimmer than a fix and fully open iris... but the fixed and fully open iris will also have the worst black levels by far. I don't know how old the '60 projector is, but at long ago as 2006, Sony had a GREAT Auto Iris algorythm.

Auto Iris only messes up MEASURED gamma, It does NOT mess up instantaneous gamma of any sequence of frames. And it only messes-up measured gamma because it does change the iris opening as you change the % white... but you never see that happen while watching a movie. Let's say you set gamma to 2.2 with the iris half open. Then you change the iris to fully closed and measure gamma again... you're going to have the SAME RESPONSE from the projector with the iris fully closed only less light comes through the optical path. The relative "shape" of the gamma curve won't change. CALCULATED gamma will change because peak white is lower and dark black is lower and that will throw the calculated numbers off a little, but the projector will send the same amount of light from the RGB light engine regardless of what iris opening you use. The iris blocks more or less light as it opens and closes... the light engine in the projector is NOT changing what it does. So as far as the light engine is concerned, it is going to produce the SAME response with every different iris opening... only the brightness of the image on the screen changes. People always think what they measure with Auto Iris enabled is so messed up that Auto Iris is the devil incarnate... and it does LOOK diabolically awful if you try to calibrate grayscale with auto iris enabled. But that's an artifact of the measurement method --- it does NOT represent what the projector is doing internally.

Most projectors that have Auto Iris have black levels that are so high as to be consideraly more of a distraction from a satisfying viewing experience than using Auto Iris... however, there are some Auto Iris implementations that are just awful... take recent Brand E projectors for example... the iris motor makes so much noise when it operates, unless the projector is in a soundproof enclosure (or booth), you are going to EASILY hear it in operation unless the soundtrack is VERY loud. Secondly, their algorithm is so bad you can almost always see the light level on the screen changig. I don't know how Sony avoids that, but they do (from 2006 forward at least).

Calibrate in fixed iris mode with the iris at a middle opening setting. When you're done, turn Auto Iris on... I've never been disappointed by a Sony product with Auto Iris from RPTVs to the new 4K projector... they all work really well and they all produce much better black levels than is possible with any fixed opening except fully closed. Unforrtunately... fully closed limits peak white so much that bright images look dull. With Auto Iris in the "full range" or "wide range" or whatever they call it, mode, you get the darkest shadows and the birghtest whites the projector can produce.

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post #7 of 12 Old 01-13-2013, 03:19 PM
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Quote:
Originally Posted by Doug Blackburn View Post

Auto iris is perfectly fine to use... opening and closing the iris should not affect gamut at all unless the projector is very strange. You NEVER should have Auto Iris activated when you calibrate a projector. If you are going to use Auto Iris (I like it quite a lot, especially Sony's implementation which is very very difficult to detect in operation... you might notice it 1 or 2 times during an average movie), when you calibrate, you should use a fixed iris opening in the middle of the range (roughly half-way between fully open and fully closed. When you are done calibrating, turn Auto Iris on and forget about it and enjoy your images. Auto Iris (especially Sony's implementation) closes the iris for darker scenes and opens the iris for lighter scenes. It will NOT make brighter scenes less bright unless you are using the "limited" version of Auto Iris present on some Sony models... the "limited" mode never fully closes nor never fully opens the iris. That could look dimmer than a fix and fully open iris... but the fixed and fully open iris will also have the worst black levels by far. I don't know how old the '60 projector is, but at long ago as 2006, Sony had a GREAT Auto Iris algorythm.

Auto Iris only messes up MEASURED gamma, It does NOT mess up instantaneous gamma of any sequence of frames. And it only messes-up measured gamma because it does change the iris opening as you change the % white... but you never see that happen while watching a movie. Let's say you set gamma to 2.2 with the iris half open. Then you change the iris to fully closed and measure gamma again... you're going to have the SAME RESPONSE from the projector with the iris fully closed only less light comes through the optical path. The relative "shape" of the gamma curve won't change. CALCULATED gamma will change because peak white is lower and dark black is lower and that will throw the calculated numbers off a little, but the projector will send the same amount of light from the RGB light engine regardless of what iris opening you use. The iris blocks more or less light as it opens and closes... the light engine in the projector is NOT changing what it does. So as far as the light engine is concerned, it is going to produce the SAME response with every different iris opening... only the brightness of the image on the screen changes. People always think what they measure with Auto Iris enabled is so messed up that Auto Iris is the devil incarnate... and it does LOOK diabolically awful if you try to calibrate grayscale with auto iris enabled. But that's an artifact of the measurement method --- it does NOT represent what the projector is doing internally.

Most projectors that have Auto Iris have black levels that are so high as to be consideraly more of a distraction from a satisfying viewing experience than using Auto Iris... however, there are some Auto Iris implementations that are just awful... take recent Brand E projectors for example... the iris motor makes so much noise when it operates, unless the projector is in a soundproof enclosure (or booth), you are going to EASILY hear it in operation unless the soundtrack is VERY loud. Secondly, their algorithm is so bad you can almost always see the light level on the screen changig. I don't know how Sony avoids that, but they do (from 2006 forward at least).

Calibrate in fixed iris mode with the iris at a middle opening setting. When you're done, turn Auto Iris on... I've never been disappointed by a Sony product with Auto Iris from RPTVs to the new 4K projector... they all work really well and they all produce much better black levels than is possible with any fixed opening except fully closed. Unforrtunately... fully closed limits peak white so much that bright images look dull. With Auto Iris in the "full range" or "wide range" or whatever they call it, mode, you get the darkest shadows and the birghtest whites the projector can produce.


Dont mean to hijack the thread but I own a mits 73835 dlp that has an auto iris that cannot be adjusted or turned off by the user. Would you recommend calibrating grayscale with apl patterns or standard windows patterns? Using apl patterns gamma measures better but you bring up an interesting point regarding measurement vs what is actually happening. Grayscale adjustments do vary pending if i use apl or standard patterns and im not sure which is technically correct.
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post #8 of 12 Old 01-14-2013, 10:31 AM
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I've never heard of an auto iris that cannot be turned off before... are you sure? There isn't a control in some other part of the menu system? Not in the part of the menu where the Picture controls are but in one of the other settings categories--maybe where you select high or normal lamp mode or something like that? Or in the ADV1 or ADV2 menus?

Patterns with constant APL (average picture level) "should" keep the iris from moving during calibration. The real question is, what average level should the patterns hit? I'd think if your 100% white level measures, say, 30 fL, that your patterns should produce about 15 fL as an overall average for the whole frame so your patterns stay roughly in the middle of the luminance range so, presumably, the iris would be roughly in a middle position for the calibration. If you haven't got that level of control over the patterns (and figuring out what the pattern needs to be doing to maintain an average of 15 fL when you look at the entire screen (not just the small area your meter measures) is pretty tricky.

A "perfect" APL calculation would total the luminance for every pixel triplet (RGB) on the screen then divide by the number of pixels that were measured. That's, obviously difficult to do! The iris opening is, most likely, controlled by APL... the lower (darker) the APL, the more the iris closes. The higher the APL, the more the iris opens. Plasma ABL patterns attempt to keep a steady-state "total screen brightness" during calibration should certainly help if you really can't disable the auto/dynamic iris during calibration.

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post #9 of 12 Old 01-14-2013, 04:15 PM
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Quote:
Originally Posted by Doug Blackburn View Post

I've never heard of an auto iris that cannot be turned off before... are you sure? There isn't a control in some other part of the menu system? Not in the part of the menu where the Picture controls are but in one of the other settings categories--maybe where you select high or normal lamp mode or something like that? Or in the ADV1 or ADV2 menus?

Patterns with constant APL (average picture level) "should" keep the iris from moving during calibration. The real question is, what average level should the patterns hit? I'd think if your 100% white level measures, say, 30 fL, that your patterns should produce about 15 fL as an overall average for the whole frame so your patterns stay roughly in the middle of the luminance range so, presumably, the iris would be roughly in a middle position for the calibration. If you haven't got that level of control over the patterns (and figuring out what the pattern needs to be doing to maintain an average of 15 fL when you look at the entire screen (not just the small area your meter measures) is pretty tricky.

A "perfect" APL calculation would total the luminance for every pixel triplet (RGB) on the screen then divide by the number of pixels that were measured. That's, obviously difficult to do! The iris opening is, most likely, controlled by APL... the lower (darker) the APL, the more the iris closes. The higher the APL, the more the iris opens. Plasma ABL patterns attempt to keep a steady-state "total screen brightness" during calibration should certainly help if you really can't disable the auto/dynamic iris during calibration.

Definitely cant turn the iris off. The mits dlp's that have the auto iris have no setting anybody could ever find in the service menu to disable it. The only apl patterns i have used are from the avs 709 disc. I guess i will continue to use those patterns.
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post #10 of 12 Old 01-15-2013, 11:08 AM
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There is a serviced menu setting in some of the Mits for the iris. The problem is that it doesn't really do anything or if it does, it won't stick. My 82837 has the service menu setting been a long time since I was in there. My 92840 has no dynamic iris which simplifies the whole issue

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post #11 of 12 Old 01-15-2013, 11:35 AM
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One thing I forgot to mention in the previous post...

Auto Iris programming may ignore the perimeter of the screen and only be affected by the central 2/3 or so of the screen. So your "constant APL" patterns need to be customized for the area of the screen your TV uses to determine iris opening... that can be done, but it takes some time. You start with some size border and a smaller sized central area of the pattern (like maybe 10% of the screen area). Then you change the border to black and white while measuring the "never changing" central area of the screen. When you reach a point where switching the border between black and white does not change the measurement you get from the central area of the screen, you found area of the screen that the auto iris algorithm ignores.

So if the ABL plasma patterns use the entire frame (I've never seen them myself), they may not stop as much iris action as you'd like.

Once you know how much of the perimeter of the images is ignored by the auto iris algorithm, you can create APL patterns that provide consistent APL over the area of the screen that IS used by the auto iris algorithm. To do this, you'd be creating test images with some sort of tool like PhotoShop or it's closest free equivalent... probably Paint.Net (though Paint.Net is a little tricky to work with at the pixel level because of the way their tools work). Create a 1920x1080 work space, and resize your center and borders to create the test images you'll use to determine how the TV responds.

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post #12 of 12 Old 01-22-2013, 02:24 PM - Thread Starter
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Ok,

I'm going to turn it back on. (The iris that is.)

I do know that with the "slow" setting I can't detect the iris and it makes black a lot lower.

Ill have to check that it doesn't dull white but I can adjust how far it opens if it does. (I have the service manual.)

It's funny how simple things are but how much learning I can do anyway.

I love setting up projectors,... It's so much fun.

-Brian
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