| Author |
Message |
kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
|
|
| Back to top |
|
 |
Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
|
|
| Back to top |
|
|
garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
|
| Posted: Wed Apr 23, 2008 4:08 am Post subject: |
|
|
|
The Vpp (peak-to-peak voltage) of the video signal. You put a scope across a terminated (plugged into the projector, which provides a 50ohm load) video line, or you terminate the video line with a 50ohm resistor and put the scope across that. Then you look at the video waveform for something like a stairstep pattern. Most projectors want 0.7V peak-to-peak. Unfortunately the gamma boosters work by boosting the entire waveform, producing a larger Vpp, which can overload the input circuitry.
|
|
| Back to top |
|
|
Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
|
| Posted: Wed Apr 23, 2008 4:25 am Post subject: |
|
|
| garyfritz wrote: | | The Vpp (peak-to-peak voltage) of the video signal. You put a scope across a terminated (plugged into the projector, which provides a 50ohm load) video line, or you terminate the video line with a 50ohm resistor and put the scope across that. Then you look at the video waveform for something like a stairstep pattern. Most projectors want 0.7V peak-to-peak. Unfortunately the gamma boosters work by boosting the entire waveform, producing a larger Vpp, which can overload the input circuitry. |
So I would probe say the RCA conenctor on the VNB of my Marquee's neck board, the outer part of the connector to the grounding lead of my scope and the probe to a lead from the center pin or a trace from it, correct?
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
|
|
| Back to top |
|
|
garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
|
| Posted: Wed Apr 23, 2008 4:37 am Post subject: |
|
|
|
I don't think so. By that point the video input signal has been converted to whatever the VNB needs. You need to measure the video signal before it ever enters the projector. Might be easier to put a Tee-connector in the video line and measure off that, or just terminate the video line with a 50ohm resistor.
|
|
| Back to top |
|
|
Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
|
| Posted: Wed Apr 23, 2008 4:42 am Post subject: |
|
|
I see....how would it be done if I am using HDMI to a moome card? take the reading from the leads out of the moome card before they go to the first set of op amps on the vim? those are easy to connect to from the socket on the VIM where the moome card connects to i supose...unless that line of thinking is wrong. I would also have the moome's gamma turned all the way down then.
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
|
|
| Back to top |
|
|
WTS
Joined: 08 Mar 2006
Posts: 1276
Location: Calgary
|
| Posted: Wed Apr 23, 2008 4:46 am Post subject: |
|
|
No, you need to terminate it with a 75R resistor not 50R.
_________________
Thanks
Walter
|
|
| Back to top |
|
|
Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
|
| Posted: Wed Apr 23, 2008 5:15 am Post subject: |
|
|
| WTS wrote: | | No, you need to terminate it with a 75R resistor not 50R. |
How would you do that with the moome card ? When the card is conected to the VIM on a marquee the pins are exposed for RGB, would this be where i would scope them with out having to add a resitor? When terminating say a regular Video RCA with a resistor how would that be done? Sorry just got my scope and still learning where to do the measurments from.
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
|
|
| Back to top |
|
|
WTS
Joined: 08 Mar 2006
Posts: 1276
Location: Calgary
|
| Posted: Wed Apr 23, 2008 1:33 pm Post subject: |
|
|
If you have an internal card just connect the scope probe to the RGB input pins, you don't need to add any resistors because the output is already being terminated by the VIM input.
Put your scope channel on .1v/div and adjust the contrast pot on the Moome card until the displayed squarewave (100ire 10% window) is 7 divisions high on the scope screen, done, enjoy.
Now everytime you readjust your gamma you should redo your contrast setting on the Moome card too.
_________________
Thanks
Walter
|
|
| Back to top |
|
|
garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
|
| Posted: Wed Apr 23, 2008 1:45 pm Post subject: |
|
|
Whups! My bad, I was thinking it was 50. Thanks for the correction, Walter.
Too bad Moome didn't include the output-adjustment feature on his earlier products. I think it should be a requirement in any gamma-boosting product that boosts the Vpp. Ideally it would self-adjust but I suppose that would be difficult.
|
|
| Back to top |
|
|
Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
|
| Posted: Wed Apr 23, 2008 2:47 pm Post subject: |
|
|
| WTS wrote: | | If you have an internal card just connect the scope probe to the RGB input pins, you don't need to add any resistors because the output is already being terminated by the VIM input. |
Oh so on the unused RGB BNC's there is a signal present, when the HDMI cable is sending the digital signal to the moome card, the card then converts it to Analog and that signal should be also present on the BNC's, is that right?
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
|
|
| Back to top |
|
|
WTS
Joined: 08 Mar 2006
Posts: 1276
Location: Calgary
|
| Posted: Wed Apr 23, 2008 3:34 pm Post subject: |
|
|
No, it won't be present on the bnc's. I thought you had access to the RGB output pins on the Moome card, that is where you need to connect the scope probe.
_________________
Thanks
Walter
|
|
| Back to top |
|
|
Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
|
|
| Back to top |
|
|
VideoGrabber
Joined: 09 Apr 2006
Posts: 933
Location: Michigan
|
| Posted: Thu Apr 24, 2008 5:24 am Post subject: |
|
|
Kal commented:
> I can easily do 8 ftL too but the image is a lot less lifeless. <
Hmm. So you prefer more lifeless? I take it you're going for the living dead look?  LOL
(I'm guessing you meant "less lifelike". Couldn't resist pulling your leg.)
_________________
- Tim
|
|
| Back to top |
|
|
kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
|
|
| Back to top |
|
|
WTS
Joined: 08 Mar 2006
Posts: 1276
Location: Calgary
|
| Posted: Mon Apr 28, 2008 2:14 pm Post subject: |
|
|
Kal,
After you looked at my HCFR files you siad there was no data for the primaries, and I just got to thinking, is it necessary to do a snapshot of the primaries. DOes HCFR need this info for accuracy, I'm wondering if I need this for the HCFR probe.
_________________
Thanks
Walter
|
|
| Back to top |
|
|
kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
|
|
| Back to top |
|
|
Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
|
|
| Back to top |
|
|
kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
|
| Posted: Mon Apr 28, 2008 5:47 pm Post subject: |
|
|
You missed something. You also didn't read the guide it seems. 
To quote myself:
| Quote: | The points at the tips of the triangle are called the 'primaries' as they represent the 3 primary (pure) colours that make up all of the other colours within the triangle. In a follow up guide we will show you how to measure your TV or projector's primary colours which will map out your own triangle of colours, effectively showing you want range of colours your display is able to reproduce. In an ideal world we want the display's colour range to map exactly to the SD or HD colour range. It's \important to remember is that even an accurate greyscale does not guarantee that we will display colours accurately. How accurately that colour matches the SD or HD defined value for that specific colour depends entirely on how accurate the display's primaries are to the SD or HD primaries in addition to how well the greyscale is set.
Primaries generally cannot be altered in displays, except in some high end projectors or scalers with a very advanced Colour Management Systems (CMS). We won't get into doing this in this guide as it is too projector or scaler dependent (there are no standards as to how to adjust primaries). Getting a CRT projector's primaries closer to the SD or HD targets is the main reason why some lenses or glycol is tinted or colour filtered. CRT projectors without some form of tinting (i.e.: ones who's green and red tubes look white when you peer into the lenses) will have greens that are shifted to the right a lot causing greens that are too yellow, and reds that are shifted causing them to be too orange. This is why tinting glycol for air-coupled CRT projectors or adding tinted C-elements for liquid-coupled CRT projectors is so popular (See here for more information). Modifications like the Joustmods.com HD144/145 lens adapter kit are also popular as it allows you to replace your clear HD8 lenses with colour filtered HD144 or 145 lenses to effectively correct the primaries.
Most digital projector primaries fall considerably outside the standard SD and HD colour spaces making the colours too vibrant. You may think this is good as it'll give you a broader range of colours but it's not true. Instead, when the projector is asked to display a specific shade of colour, that colour will be too vibrant and not what was actually recorded on film. This may not be too noticeable on cartoons or objects that we're not too familiar with, but a digital projector with primaries that are too far out will cause (for example) green grass to have an almost neon-like glow to it at times. Definitely not what the director intended. This is the main reason why many people complain that digital projectors out of the box look 'cartoony'. If you buy a digital projector, make sure to do some research into how accurate the primaries are or make sure some method to adjust the primaries is offered in order to get them closer to the correct primaries.
Again, we won't be explaining how to do primary adjustments in this guide as while not that complicated, it's far too projector-specific.
|
Read the whole section on the CIE graph again.
Kal
_________________
Support our site by using our affiliate links. We thank you!
My basement/HT/bar/brewery build 2.0
|
|
| Back to top |
|
|
Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
|
|
| Back to top |
|
|
|
|
