Fixing the Oversaturation Problem in the JVC-RS1 - Page 3

That should be "you certainly do not need to apologize". "Need not" is.....well, just bad written English!

Thanks Otto!

I think I understand now.

In layman's terms, we can think of the 3 dimensional CIE as a hexahedron with the point at the top of the Z axis as white and the point at the bottom of the Z axis as black. If so, the 2 D CIE is merely a cross section of the 3D structure. Is the Z axis the grayscale?

Ok, in context of de-saturating the color gamut perceivably, if the color control was purely a color intensity adjustment and functioning properly, as this adjustment approaches 0 how much would this impact the saturation on the cie chart. Would you expect the decrease of the Y funtion of the saturation to be negligable and within the typical error tolerance of measuring equipment or would the lowered intensity account for a repeatable, significant and perceivable shrinkage of saturation.

I think my sentence versus yours is more a matter of style differences as opposed to a grammatical error. I ran it through two different grammar checkers and neither found a problem with the sentence construction. I do admit your sentence is more straightforward and certainly scores better on a readability index.

I have a difficult time with my sentence being considered "bad written English". I wouldn't enjoy much of what I read if I evaluated everything on strict grammar rules. Precise, straightforward sentence construction makes for very dull prose. I have been put to sleep many times by grammatically correct technical writing!

But, what do I know? I once flunked English composition.

Well, crap, dude, you like just took all the fun out of it!

I was just trying (unsuccessfully I might add) to be a little funny. "Need not" isn't really improper.

Perhaps the funniest thing of all is the fact that you ran it through two different grammar checkers and neither found a problem with the sentence construction!

the issue is with your sentence syntax -- but Rob is no more proper. Bad isn't a proper adjective.

"Bad written English" should read "English written poorly" or "poorly written English"

Other examples of poor diction (word choice): usage of good vs. well.

E.G.

How are you doing -- I'm doing well (not Good). That was a good move. Yea, I do that well (not good).

English is fun -- aint it?

A classic case of blue brains, man I hope you get your fix soon.

See, I just knew it was a matter of time before some proper, uppity, better than all of us snob would show up to tell both Maddog and me how crappy our English is!



Just kiddin' Forceflow!


That's just plain classic.

It's funny 'cuz it's true!

I really need to calm down...........

Rob,

I'm the dumbass that spent almost 200k on a pointless education! I think I spend more time writing on this informal forum than for work (depends on the day -- inverse relationship).

I do know that both you and I will be posting far less once we get a new PJ (you're getting yours soon right??). So hopefully I can begin applying myself more towards my work rather than checking in on the RS-1 and Sharp 20k threads.

I do hope that you post your impressions of your RS-1 and whether you honestly feel that they are oversaturated. That is my biggest concern or I'd pull the trigger...

Blue has little intensity (in terms of lumens) at full strength so it too will not change much in lumens as you lower the color control. It will NOT go black either.


I never said anything about contrast (i.e. gain)

hmmm, perhaps I don't read too well. Would you like to re-state the following:
"The standard user Color control is NOT an effective means for reducing the measured gamut (or saturation) of ANY display that I've ever encountered,"
If that number of displays would be the RS-1 and only that projector, then you are apparently correct. I assumed because you said "displays" you meant more than 1.

yep, I'm with you.


In general you are wrong.


What display are we talking about here? Is this ANY display or the RS-1?


My recommend method is to reduce the magnitude of the component signals; that is the way most color controls work. Pulling the Pb and Pr signals on a typical display will accomplish the same thing and you will be left with the same luminous signal. If you have an analog component source, please try that on your RS-1.


I can not make any clearer that I am refering to a standard display. Do your test with "ANY" other display.

Let's look at the REC 709 equations:

Y' = 0.2126r' + 0.7152g' + 0.0722b'
Cb' = 0.5389 (b'-y')
Cr' = 0.6350(r'-y')

That means that a 100 percent red image becomes:

Y' = 0.2126
Cb' = -.5389
Cr' = .4224

Now, a normal color/saturation control set to its lowest value will reduce Cb' and Cr' to 0 (or 128 in the digital domain where there is an 128 count offset.)

So what are you left with?

Y' = 0.2126
Cb' = 0
Cr' = 0

That sounds a lot like 21.3% luminous signal to me.

Please do your test with another display using a simple color control. You've proved the RS-1 is goofy (and I do appreciate the hard data) now back-up your claim that other displays are similar.

Also, it appears courtesy of your data, the only way (baring a firmware fix or service menu adjustment) to affect saturation would be with analog attenuators I mentioned earlier. Let's hope it doesn't come to that.

-Mr. Wigggles

Ps. REC 709 is the defining document for HDTV colorspace written by the ITU; SMPTE acknowledges it as the standard. However, there is still some ambiguity in the terms. The ITU uses Cr and Cb for both digital and analog signals while SMPTE use Pr and Pb to for analog signals and Cr and Cb strictly for digital. I prefer SMPTE's terminology but in this post where I quoted REC709 I stuck with their usage of Cr and Cb.

Clear communication, oral or written, is near and dear to my heart. It doesn't have to be perfect, just understandable. 99.99% of the post on this forum are clearly understandable and obviously written by literate people.

Living in the New Orleans metro area, I see a large number of people that can't speak or write in complete sentences. The public educational system is so bad here that we recently had a class valedictorian that couldn't pass the basic state graduation exam!

I do have one great personal accomplishment in teaching English. A Dutch friend that speaks 5 or 6 languages fluently once heard me, in a moment of anger, use the phrase "He doesn't know sh_t from Shinola!" when describing a particularly pompous client. After I explained it to him, he thought it was so funny that he made it part of his repertory of American idioms.

So much for my attempt to improve the use of the English language.

200k on education? Ouch. I do know a few people that spent that much, but they are doing quite well now (2 dentists and an attorney).

I think you are not giving yourself enough credit though. You write English very well!

Yes, once I have my RS1 up and running, and tweaked with the help of others on this forum, my posts will diminish dramatically, just as they did last time I upgraded.

And yes, you will get my honest impressions on the color/over-saturation issue (whether you want it or not)!

Back on topic...

Yes, the colors are over saturated but I don't really mind. The only time I actually notice the over saturation is on something live with a lot of grass like a golf tournament. The colors in movies and TV series are so manipulated that I rarely notice the overdone colors. If you are a stickler for accurate colors, they will probably bother you.

I am more pissed about the 480i via HDMI not working. I read the specs and expected it to work so I bought the HD-A2 instead of the HD-XA2. No point is spending the extra bucks on a redundant VP for watching SD DVD's, right? Wrong! I really had hopes of only using HDMI to the projector and greatly simplifying me wiring. It now looks like I will have to keep component cables and switching in place.

"Tom,

You are wrong and the proof is simple. Take the color control on any projector to zero. What does yellow look like? It will look very light gray not black.

Saturation is being changed not intensity/lightness.

-Mr. Wigggles "

"No, I'm not.

Your results with yellow are easy to explain. Of all the primary and secondary colors, yellow has the highest intensity, over 90% of reference white. Color controls have a limited range of adjustment. "

You haven't refuted what to me looks like inescapable logic.

Foeget what color you start at, turn down the color on most pj's and you end up in the middle of of the triangle w/no color, no matter the intensity from black to white.

If that's not reducing saturation (to zero), then what is?

Yes, but only if you can get something like ffdshow into the signal chain. Fixing the DVI RGB matrix bug would be pretty simple with a custom matrix (assuming the bug reproduces consistently, which may not be the case). Fixing saturation is even easier.

Problem is, you will never be able to use ffdshow with DRM'd sources like HD DVD / Blu-Ray / CableCard. All you're left with is things that work at the driver level: the nVidia/ATI control panels, PowerStrip, and your system-wide color profile (ICM). None of those offers a saturation control as far as I can tell. (

maddogmc: "I am more pissed about the 480i via HDMI not working. I read the specs and expected it to work so I bought the HD-A2 instead of the HD-XA2. No point is spending the extra bucks on a redundant VP for watching SD DVD's, right? Wrong! I really had hopes of only using HDMI to the projector and greatly simplifying me wiring. It now looks like I will have to keep component cables and switching in place."

I am about to buy an HD-A2 to go with an upcoming RS-1, and expect to send the projector 1080i over HDMI. Why was your choice of the HD-A2 wrong, and why would an HD-XA2 be required? Why send 480i? The RS-1 deinterlaces 1080i to 1080P very well, no?

I think he must be referring to the overscan on 480i/p signals. I use the A2 at 1080i and the picture is fantastic. IIRC Greg Rogers found no issues with the deinterlacing at any input resolution.

I assume he was thinking that the scaling and deinterlacing of the Gennum in the RS1 would be better than the chip in the A2. Now he needs to use the A2's processing for SD's instead of the RS1's. The XA2 uses the Realta chip, so this would not have been an issue.

I am beginning to feel like I'm debating a group of medieval theologians. Forget the evidence. Trust "inescapable logic" instead. Yes, of course, as I've said about a half a dozen times, you CAN use the color control to lower saturation exactly as you just described. The problem is that in doing so you lower the intensity even more, which really screws up the image.

I see that my experiment was not enough because it was just one display. OK, I'll repeat it tonight on a Sony CRT. And, BTW, it wasn't the RS1 I used for the data. It was the Sharp 20K.

Jason got it right. The A2 does not up convert SD DVD's nearly as well as the XA2. This would not be a problem if 480i via HDMI worked as intended on the RS-1. I expected to use the Gennum in the RS-1 for deinterlacing and scaling SD DVD. Since it does not, I have the choice of replacing the A2 with a XA2 or running component cables just for SD DVD. I'm still hoping for a fix from JVC since neither option appeals to me.

I guess you could say that, yes. I must say I'm not an expert in this field, I'm just trying to translate the parts of my training that I believe I understand, into something that makes sense to people who haven't been trained in colorimetry. Problem is, simplifying stuff usually tends to result in less accurate statements. But if it helps in understanding the big picture (pun intended), I guess it's OK to cut a few corners here and there...

At black, there is per definition 0% saturation. To increase saturation, you have to increase light output to a point where our eyes can see it. On the other end of the hexawhateveritwas, towards white - as I have been told, it goes _very_ far out before it becomes a single point again. The reason the primary moves inward when you decrease luminance, is (as far as my brain interprets my knowledge) that you basically still have the same saturation, _relative_ to the part of light that we can see - which now has become smaller. Since the CIE chart is 2D, it can't show this properly.

That is very interesting. I'm not shocked that the 20K would exhibit that behavior, but I am a little surprised that the basic "color" control would behave like that. That projector has a fancy CMS system but the basic user color control should, in-principal behave linear and not in the way you have shown.

I still argue that a "color" control like the one you tested is a poor design and such behavior is not indicative of most displays. (I am assuming you weren't overdriving the red primary when you did your above test.) I can certainly test things on a few displays of my own; you don't have to go 10 "clicks" to start to see a color saturation change. I can take some Adobe RGB images with my Canon XT to chart the behavior.

-Mr. Wigggles

Ps. Your latest post was a bit of bummer. I had hoped your numbers were from the RS-1 specifically.

Show where the SMPTE standards define the function of the color control in digital circuits - and requires that implementation in consumer electronics. Again you are using professional analog thinking in a consumer digital world. Marketing can make the color control do whatever they want it to do. I have seen tint contols that posterize and randomize the colors rather than just do a slight push to green or magenta faces like you would expect a tint control to work - they did it because they could. Poynton's "Digital Video and HDTV" text devotes a whole chapter to the various brightness/contrast implementations he is aware of - if that cannot get done "right" what makes you think color implementations are "right"?


Both Tom and I are professional calibrators with real world experience on digital front projection. You are basing your argument on a reality that does not exist - that controls work like you think they should. Calibration is about learning how controls actually work - not how they "should" work. It is both of our experience that using the color control to reduce the gamut to standard results in horribly off video.

Here is a thread where this was done on a Sony Pearl...I personally verified the calibration spreadsheet - exactly what Tom is demonstrating was done- perfect gamut at huge cost to Y.

http://www.avsforum.com/avs-vb/showthread.php?t=767155

Here are the results from a Sony CRT. You have to use a little imagination here, because the color is not oversaturated to begin with.

Rec. 709 standard for red
x .640
y .330
Y .213

Measured initial values
x 0.627
y 0.339
Y 0.209



Color Control-------x---------y---------Y
0------------------0.627-----0.339-----0.209
-2-----------------0.624-----0.341-----0.180
-4-----------------0.623-----0.329-----0.159
-6-----------------0.619-----0.338-----0.143
-8-----------------0.615-----0.335-----0.124



Exactly the same result. The saturation was reduced moderately, but the effect on intensity was catastrophic, showing a net loss of approximately 40%.

To make it clear Y referred to here is the CIE luminance measure from the XYZ tristimulus data - it is not the Y in component video (which Poynton calls luma - though this is not standardized). While related - they are not the same measure - but just a common symbol used at different points in the video/display/eye chain - gamma and units are different.

I dont get this man, if the colors are oversturated turn the colors down, chroma-etc- on your dvd player-display. Green will go to black and white, adjust it to the level it looks realistic to you.

At this point I don't think anyone is challenging Tom's measurements, they clearly show the color control effect on both saturation and brightness on the Sharp and his CRT PJ. His measurements are consistent with my own measurements using the JVC's color control with both saturation and brightness being affected.

I agree with statements that using the color control to bring in the primaries due to the screwed color brightness is a very bad idea assuming there's no other method to bring the brightness back up. But if, and that's a big if at this point in time, color brightness can be raised somewhere else in the chain to compensate for the loss at the PJ leaving the primaries untouched then this may be a reasonable method for some to, in effect, move the primaries around.

A quick test with an component output Pioneer I dug out of the closet shows that the color control within this unit affects only the color brightness leaving the primaries untouched. Same thing I see when displaying 100% color field vs 75% fields, the primaries are not affected only brightness or luminance. With a small amount of luck my next player may perform similarly though I'm not banking on it. It's not a big deal anyway, the oversaturated colors don't prevent me in any way from enjoying the performance of the JVC, I'm just going through this process to see if can be done.

The last time I checked, neither my OTA receiver nor Cable box had color controls so I am left with the controls on the RS-1 unless I purchase an outboard processor. If you haven't played with the color control on the RS-1, you really don't understand the problem.

For the record, it is a Sony XBR CRT direct view, not a projector.

So green became more saturated as the color control was reduced? That just doesn't make sense. Also the fact that your primaries and you secondaries don't make straight lines through the white point is a little suspect that either your equipment is not valid or once again there is something funny going on in the control.

I don't know how many clicks there are total but the idea that luma would change so dramatically without any real effect to chroma is a little hard to believe. The "y" coordinate bounced around all over the place as you lowered the "Color" control.

-Mr. Wigggles