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Shadow detail/gamma enhancement for the analog sources - Page 3  

post #61 of 492
benny,
That is great. This is looking like a very nice solution.

tse,
Are you and CJ related or the same person?:) You both like guns and CRTs. For me, I have gotten the guns(weapons) removed from my system after my stint as an armorer in the Marines.

Ericglo
post #62 of 492
Quote:
Originally Posted by Ericglo
benny,
That is great. This is looking like a very nice solution.

tse,
Are you and CJ related or the same person?:) You both like guns and CRTs. For me, I have gotten the guns(weapons) removed from my system after my stint as an armorer in the Marines.

Ericglo
PLEASE keep this thread on track! I had a thread of my own closed ("What (other) expensive hobbies...") when it devolved into a firearms debate.
post #63 of 492
Hi Russ,

He's got a whack of opamps on those boards, I see five, a few more tse's circuit requires. Are we going to see some schematics for his design.

Thanks
post #64 of 492
Is introducing this kind of circuit, or one more complex, likely to cause audio-sync problems? Are those building test circuits, testing for this too?


John
post #65 of 492
THis will add no delays to the video.
post #66 of 492
Quote:
Originally Posted by WTS
Hi Russ,

He's got a whack of opamps on those boards, I see five, a few more tse's circuit requires. Are we going to see some schematics for his design.

Thanks
Hi Walter ...

The extra opamps allow for greater flexability and control over the output curve. The final design may well end up with only 4 but you have to start somewhere .... that's what prototypes are for. Build one .. see how it performs in realworld situations rather that just in modeling software, then refine it until it meets all design criteria. As such it's a bit premature to be discussing circuit designs.

My mate has the resources at his disposal to churn out a batch of these using the companies automated SMD layout and soldering machines so the economics of scale may prove beneficial if there is enough interest in this project from fellow forum members to justify the effort in setting up the initial automation data. Costs would be kept to a minimum and the skills required to solder SMD components would be negated.

I'll discuss these points with him and report back.

Cheers :)

Russ
post #67 of 492
Thread Starter 
The satellite receiver was offline this evening due to a big thunder boomer off to the south so I broke out an old movie, Wishmaster...Make your wish. Watched the beginning and thought "this would be a good movie to test the gamma circuit with. The very beginning is a bunch of white text on a black background. I'll use this to set the brightness so the background is totaly black. The next scenes are really dark where you miss alot of the detail unless you turn the brightness up quite a bit. This should be a good test for the circuit.
post #68 of 492
Thread Starter 
Quote:
Originally Posted by WTS
THis will add no delays to the video.
Not to be picky but it will add a nanosecond or two of delay. I doubt that you will notice. :D
post #69 of 492
Well, I guess I could have said the same, but it has no real bearing on whether you'll end up with lip sync problems or not. I would think lip sync problems would need delays of at least 100mS or more.
post #70 of 492
Quote:
Originally Posted by jtnfoley
PLEASE keep this thread on track! I had a thread of my own closed ("What (other) expensive hobbies...") when it devolved into a firearms debate.
Umm, sorry. :confused: I believe I was one of the biggest supporters of tse and his board in the beginning.


Ericglo
post #71 of 492
Quote:
Originally Posted by Ericglo
Umm, sorry. :confused: I believe I was one of the biggest supporters of tse and his board in the beginning.


Ericglo
Appologies, I didn't mean to be harsh... This is literally the third thread for the "tse gamma circuit"... Alan G had to close the previous two when the lunatics hijacked the threads with passionately ignorant posts that were WAY off-topic.
post #72 of 492
Hi Russ,

So does that mean he won't share/post his schematics, just make the boards and sell them.
post #73 of 492
Quote:
Originally Posted by jtnfoley
This is literally the third thread for the "tse gamma circuit"... Alan G had to close the previous two when the lunatics hijacked the threads with passionately ignorant posts that were WAY off-topic.
Actually the second thread wasn't closed. It just became remarkably quiet when this thread started. Even the loons realised the only reason it was being read was to keep up with developments in tse's circuit.


John
post #74 of 492
Thread Starter 
The bare circuit boards were at my door this evening. FedEX stopped by yesterday but didn't leave them even though I filled out the form saying it was ok to leave stuff last time around. Oh well. Anyhow they're here. Plan to work on them this weekend. The parts list is almost finished. Newark's web site wasn't working right or it would have been finished last night.

Cheers
post #75 of 492
Hi tse,

Well you be sure and let us know they perform now.
post #76 of 492
Quote:
Originally Posted by jtnfoley
Appologies, I didn't mean to be harsh... This is literally the third thread for the "tse gamma circuit"... Alan G had to close the previous two when the lunatics hijacked the threads with passionately ignorant posts that were WAY off-topic.
Why don't you ask "tse" if the subject of gamma, is or is "not" related to his project? In fact, if you read tse's postings, he seemed to be fairly interested according to his own comments!
tse's project is designed around the near black gamma linearity issue?

thomas :)
post #77 of 492
Quote:
Originally Posted by tbrunet
Why don't you ask "tse" if the subject of gamma, is or is "not" related to his project? In fact, if you read tse's postings, he seemed to be fairly interested according to his own comments!

thomas :)
I think you missed the beginning of that exchange... Ericglo made a post which was terminated by a joke regarding firearms (IIRC,) hence my reaction. Two prior threads of Tse's on this topic were closed and aborted because of off-topic posts inspiring lunacy.
I don't want to become this thread's r@sster-style vigilante but I _do_ want to see boards fabbed!
post #78 of 492
Thread Starter 
I wish that I hadn't brought up the trip to Melbourne. Sorry everybody. It does suck when a thread that people are interested in disolves into chaos.

Anyhow, the boards are here and I started stuffing them on friday and soon realized that I didn't have all the resistors that I needed. Everything else was here but I overlooked the easy stuff. So the resistors will be here next week and the board should be working by then.
post #79 of 492
Quote:
Originally Posted by tse
Anyhow, the boards are here and I started stuffing them on friday and soon realized that I didn't have all the resistors that I needed. Everything else was here but I overlooked the easy stuff. So the resistors will be here next week and the board should be working by then.
What source device(s) do you plan to use for testing this? One reason I ask is because the stock JVC 30ks seem to have some issues near black, like not passing blacker-than-black and maybe more that Mike Parker has mentioned. Do you have any 1080i component sources (like an HD-TIVO)?

--Darin
post #80 of 492
Thread Starter 
The only decent source is 480p from an Avia DVD player. That's my main interest though I'm soon going to get satellite HDTV.
post #81 of 492
Thread Starter 
The green channel and the DC restore stuff is together.

A few pictures.

A stairstep pattern with the top trace being the input, the bottom is the output.

A finer stairstep pattern.

A multiburst pattern with the highest frequency burst just before the blanking interval at 125MHz.

Sorry about the bad quality of some of the pictures.
LL
LL
LL
post #82 of 492
Thread Starter 
A quick shot of the board.
LL
post #83 of 492
Hi tse,

Looking good, but hey, no smd components. So what are the R values you're using for the scope pics.
post #84 of 492
Thread Starter 
Finished stuffing the board this evening and hooked it up to the projector. With the brightness set so the blacks are totally black I can see details in the darker scenes that before had me adjusting the brightness up. One thing that is different is that in one scene that was dark and smokey some "banding" was visible that I've never seen before. It's definately a move in the right direction.
post #85 of 492
The problem with "gamma correction" is that it will likely reveal the limitations of DVD, especially poorer transfers. By boosting gamma (contrast for the darker areas of the image) all sorts of artifacts can potentially rear their ugly heads and so one should be aware that this isn't a panacea for black level issues. Raising black level (brightness) doesn't seem to cause as many problems, but of course it defeats our objective.

Denon DVD players (some of the more expensive ones) have ten point gamma correction and this might just be the tool some of us are looking for.

Cheers,

Grant
post #86 of 492
Quote:
Originally Posted by Deja Vu
Denon DVD players (some of the more expensive ones) have ten point gamma correction and this might just be the tool some of us are looking for.
The Lumagen has 5 point (100, 80, 50, 30, and 20 IRE). Unfortunately, none of these do it in small increments way down low like tse's solutions, so his should be a better solutions that these.

Dave
post #87 of 492
Quote:
Originally Posted by Deja Vu
The problem with "gamma correction" is that it will likely reveal the limitations of DVD, especially poorer transfers. By boosting gamma (contrast for the darker areas of the image) all sorts of artifacts can potentially rear their ugly heads and so one should be aware that this isn't a panacea for black level issues. Raising black level (brightness) doesn't seem to cause as many problems, but of course it defeats our objective.

Denon DVD players (some of the more expensive ones) have ten point gamma correction and this might just be the tool some of us are looking for.

Cheers,

Grant
Grant,
Your post seem a little confused, TSEs circuit fiddles with gamma, which you say is a bad thing, you then recommend instead a dvd player that fiddles with gamma . There may be some merit to your "artifacts" argument, but I'll wait to see what image the circuit actually produces. The banding tse sees may be a result of over boosting the signal, so as to better see the IRE range the circuit effects.

EDIT:Remember, the aim of the circuit (I understand) is to be able to tweak the output of the projector to fit the standard display device gamma curve (2.20) the source material was (should have been) transferred in expectation of, not to twist the gamma curve like a pretzel, or adjust the gamma of the whole curve to reveal black detail.

EDIT: If limits in the quality of the source material are revealed by the fix, the solution would be to improve (or at least blame) the source, not to blame the circuit, or the projector.

John
post #88 of 492
Thread Starter 
The "banding" phenomenon might not show up with quality equipment. I was using my $59 EBay special Avia DVD player with 480p output. It has a nice picture but 10 bit? Maybe not.
post #89 of 492
Quote:
Originally Posted by misohorny
Grant,
Your post seem a little confused, TSEs circuit fiddles with gamma, which you say is a bad thing, you then recommend instead a dvd player that fiddles with gamma . There may be some merit to your "artifacts" argument, but I'll wait to see what image the circuit actually produces. The banding tse sees may be a result of over boosting the signal, so as to better see the IRE range the circuit effects.

EDIT:Remember, the aim of the circuit (I understand) is to be able to tweak the output of the projector to fit the standard display device gamma curve (2.20) the source material was (should have been) transferred in expectation of, not to twist the gamma curve like a pretzel, or adjust the gamma of the whole curve to reveal black detail.

EDIT: If limits in the quality of the source material are revealed by the fix, the solution would be to improve (or at least blame) the source, not to blame the circuit, or the projector.

John

Grant is spot on. MPEG2 is a perceptual encoding system - there's all sorts of junk hidden just below the level of perception for a "normal" system.

If you boost gamma too high you will see macroblocking and crap that is meant to be hidden.

I boost gamma a bit on my PC (1.1 or 1.2 on the Ati control panel, 1.15 on powerstrip. But if you go too far you will see junk in a dark scene.
post #90 of 492
Mark ,
I didn't say Grant was wrong, I pointed out we aren't trying to boost gamma too high, we are correcting the output of the projector to match a 2.2 gamma curve, isn't that an ideal "normal" system? One the DVDs should be transferred to match?

EDIT: tse did you do a greyscale calibration with the circuit in place, or was this basically a test to see if the circuit works?

John
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