Adjusting color intensity using RGB gain/offset - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 6 Old 12-30-2007, 07:34 AM - Thread Starter
Member
 
johnmn's Avatar
 
Join Date: Jul 2003
Posts: 56
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I have an Optoma HD7100 (and it works!). But I just got a Toshiba A3 HD DVD player, and the color is too saturated. Unfortunately, the projector grays out the Color and Tint controls when you use the DVI input (stupid!!). But there is a white balance control where I can adjust rgb gain and offset. I realize that to do this right I would need a meter, but I would like to try, just to bring the color intensity down. Factory settings are 0 for each function, so there's no risk of permanently messing up anything.

I've actually improved things a bit, I think. New settings (using 6500 temp):

R gain -7
G gain -6
B gain -5
R offset -3
G offset 5
B offset 8

But I think I could do better if I understood the concept. What normally would be the proportions of these changes for bringing down color intensity/saturation? Again, I realize that this is imprecise, but I don't think the unit was perfectly calibrated anyway. And I have a pretty good eye (and it's only my own eyes that I need to please).

Any guesstimates would be much, much appreciated! (I've checked similar threads, but they just tell the writer to get a calibration. I'd really like some tips on at least trying.)

--John
johnmn is offline  
Sponsored Links
Advertisement
 
post #2 of 6 Old 12-30-2007, 12:17 PM
AVS Special Member
 
CaspianM's Avatar
 
Join Date: Sep 2000
Location: Land of Cardinals
Posts: 5,841
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Tweaking the RGB's purpose is not color tweaking whereas is to calibrate gray scale.
I have the same pj and with gray scale done.
There is a bit of red and green color saturation in stock 7100 but that cannot be fixed by RGB.

It can be solved by an external processor that actually can do HD decoding with primery and secondary calibration option.

It is all about quality...that is the picture

JVC & NEC 8" CRT with 106" wide Stewart screen. All NHT speakers driven by Pioneer Elite AVR and bluray

Custom dedicated 8 seat theater

CaspianM is offline  
post #3 of 6 Old 12-30-2007, 12:33 PM
AVS Addicted Member
 
krasmuzik's Avatar
 
Join Date: Oct 1999
Location: NewPort, VA
Posts: 11,270
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
RGB controls change the balance of RGB that makes white - thus shifting it to one color more than the others.

If you shift RGB controls the same amount - this is identical to changing the brightness/contrast controls - which impacts the entire level of the picture.

A color control changes the level of decoded color w.r.t to the level of white - in essence it is overlayed on B&W picture. The ideal color control if pulled down completely in fact gives you a B&W picture.

So you cannot do what you want to do how you are doing it.

Try using an analog input and see if it has the video controls you need. Does no good to use the digital input if it cannot be properly calibrated. To adjust video color levels - you only need a blue filter and test DVD. If instead you are meaning the color gamut is oversaturated - that can only be fixed with the latest greatest video processors or software (see the sticky on HTPC color calibration). Turning down the video color control below what it should be will psychovisually reduce the strong color - that is the best you can do with what you have.
krasmuzik is offline  
post #4 of 6 Old 12-30-2007, 12:40 PM - Thread Starter
Member
 
johnmn's Avatar
 
Join Date: Jul 2003
Posts: 56
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Yup, I thought this was the case. I'm returning the HD DVD player--clearly any device I attach to the DVI input needs to have its own Color control. Drat!

But thanks!!
johnmn is offline  
post #5 of 6 Old 12-30-2007, 12:49 PM
AVS Special Member
 
CaspianM's Avatar
 
Join Date: Sep 2000
Location: Land of Cardinals
Posts: 5,841
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
HD7100 is pretty accurate out of box. I don't know what your talking about.

It is all about quality...that is the picture

JVC & NEC 8" CRT with 106" wide Stewart screen. All NHT speakers driven by Pioneer Elite AVR and bluray

Custom dedicated 8 seat theater

CaspianM is offline  
post #6 of 6 Old 12-30-2007, 03:47 PM
AVS Special Member
 
CaspianM's Avatar
 
Join Date: Sep 2000
Location: Land of Cardinals
Posts: 5,841
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Overall color with hd dvd A1 &2 looks great w/o any tweak and it is NOT too off the way you sound. Run it with gamma 2.2 with color temp at 7000 or native.
Read some pro reviews and you will realize that even gray scale is indeed very close.

It is all about quality...that is the picture

JVC & NEC 8" CRT with 106" wide Stewart screen. All NHT speakers driven by Pioneer Elite AVR and bluray

Custom dedicated 8 seat theater

CaspianM is offline  
Reply Digital Projectors - Under $3,000 USD MSRP

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off