DIY Calibrators Please Read - Grayscale is NOT Color Decoding (1 Viewer)

[Guy Kuo]

Not exactly on target, but here is an important maintenance message for digital projector owners... http://www.hometheaterforum.com/htf/...iodically.html

 

[Steven_Lazarus]

Great info!,
Any of you calibrators going on vacation to Italy anytime soon?? I'd be more than happy to put you up while your over here and maybe we could do some calibrating in between drinking some fine Sicilian vino and sight seeing !! Never hurts to ask !!

 

[John-Tompkins]

Is adjusting the RGB contrast and brightness settings in a PJ effecting the greyscale or the color decoding portion that is applied above the greyscale as described in the excellant post that started this thread ?

I guess what Im asking is what are the core component/adjustments that make up the greyscale ? and then what are the adjustments that comprise just the color decoding ?

 

[ChrisWiggles]

John: R, G, B drives are what control the grayscale temperature, etc. Color decoding isn't so much an "adjustment" but rather improper, non-standard color decoders in TVs to try to appeal to people's tastes in TVs. There isn't anything to "adjust" per se, but rather there should just be proper standard color decoders in a display. For those that have non-standard decoders, sometimes you can work around this with DIY fixes, or sometimes there are service or menu item options that can change the decoder back to standard. You only need to deal with this problem if your display is intentionally mis-designed with a non-standard color decoder.

Grayscale, however, is universally important to adjust on a display, but is difficult to get very accurate without proper equipment.

 

[Robert P. Jones]

Drives and cutoffs per each individual color are what control grayscale, sometimes also called gain and bias. Drives/gains control the strong, "white" light levels, cutoffs/biases/screen trimpots on the focus block control the dark information, the weak/low light levels.

This is only for the B/W information, tho all settings should be close to optimum to avoid unpleasant interactions between grayscale and color decoding. Try turning down the color intensity on most Tosh RPTVs to its lowest setting, which should be pure B/W, and instead of gunmetal gray you get Kryptonite green!

What controls tweakable color decoders are master color and tint, then R-YR, R-YB, G-YR and G-YB service menu registers - or variations of those - which are the individual color and tint controls for red and green.

Not all color decoders are tweakable. The early Mits's had - and the current and past Hitachis and Sonys have - tweakable decoders. Not so for Tosh and Pioneer, but there is rarely a need for retweaking color decoding on those anyway. Pannys have limited tweakability on theirs, but again not a strong need for it anyway, beyond what they can do.

Mits's have always taken great liberties with the industry standard, and have always put out what Chris has called non-standard color decoding. They used to make it retweakable to standard, got incensed when they tried to then shut us out from retweaking back to industry standard and we found workarounds involving invading their I2C bus and accomplishing the desired improvements anyway, and now only allow such retweaking in their User menus via the PerfectColor settings.

They insist that their customer base has always PREFERRED red pushed color decoding. When that client base realizes that red push is the same thing as blue/green diminish - that when fleshtones are prioritized that blue and green become wilted - I hope they will revolt!

RGB inputs have no color decoding at all - whatever decoding is tweakable even in terms of color and tint is found in whatever is sending the signal to the pj via the RGB circuits.

Hope this helps -

Mr Bob

 

[ChrisWiggles]

RGB inputs have no color decoding at all - whatever decoding is tweakable even in terms of color and tint is found in whatever is sending the signal to the pj via the RGB circuits.

Bob: I thought it was you that pointed this out to me, but in any case I think it is the mitsubishis that actually *convert* RGB inputs into component, then run them through their color processing/decoders, and will actually introduce red push problems *even* on RGB inputs. If the RGB inputs are not converted internally to something else, there should be no color decoding occuring, and no color adjustments except greyscale RGB gains and G2. Unfortunately in some consumer displays such as many(all?) Mits units, these problems are actually *added* into inputs that would otherwise have totally bypassed the color decoding (since there's nothing to decode into an RGB signal since the input is already RGB!).

 

[Wayde_R]

This is a bit off topic maybe.

How do I become a TV calibrator? How do I learn more about it? I mean, learn more about taking up the trade. Are there courses? Do TV shops do this or is this a specialized industry with few outlets? Does it fall under Cedia HT optimization? Is Cedia the given standard by which HT calibrators are measured? Any suggested reading?

Thanks

 

[ChrisWiggles]

You could try an ISF course. You need the tools and the experience, and that's not really teachable.

 

[Wayde_R]

So, people who do HDTV calibrations were never taught?

 

[Carmine]

my new sony tv has controls for white balance in the user menu. the only thing is they are labeled "BIAS" & "GAIN". which of these is equivalent to "CUT" & which is equivalent to "DRIVE"?

thanks very much

Carmine.

 

[ChrisWiggles]

Usually bias=cut=G2

gain=drive

There are cases where they may mean different things than this, but if you are in a white balance menu, you can be pretty positive that this is the case.

 

[Robert P. Jones]

quote:

quote:

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You could try an ISF course. You need the tools and the experience, and that's not really teachable.

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So, people who do HDTV calibrations were never taught?

[/quote]

You can't teach tools and experience.

I was already a repair service tech when I got into this, so I had access to a lot of resources most don't have.

But there are a lot of guys who are not repair techs who have very successfully gotten in, and are doing fabulously well. Craig Miller is booked months in advance all over the country - which he travels in a motor home, with his precious, Sue - doing Mit calibrations because he has made that his exclusive baby. The word is out far and wide on his excellence, and I have learned lots of stuff from him as well. I returned the favor for some of the wealth of stuff I have learned from him and lent a hand when he didn't know about Schiempflug alignments, and how to get the optical focus on any given color even across the screen when it is not, OOB.

I don't know if it is OK to give out competing website info - if so let me know and I will post a few resources sites, where I have gotten a lot of my advanced knowledge.

Or contact me directly. If you are sufficiently far away that you would present no competition in my home area, I will even train you myself, if you wish.

Mr Bob