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question on tint control


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#1 of 6 ThomasL

ThomasL

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Posted February 10 2008 - 05:08 AM

Hello all. Hopefully one of the calibration experts can answer a simple question I have regarding Avia and color settings.

If a set's saturation and tint/hue controls have been calibrated using the blue filter and the set also has excellent color decoder results (all primaries are at 0 percent using the Avia II color decoder pattern) then what does it mean when one goes into the red and green bars test pattern and the tint/hue are a bit off? i.e. saturation is perfect as the color decoder pattern indicates yet in order to get the tint set for green, I have to tick up the controls about 5 notches. Red is actually the same as blue. Is this indicative that the set's primary and secondary color points are off the standard? I would assume that by having to tick up the tint control on the green bars pattern (which moves it toward Red and away from Green on the actual tint setting) that it means in order to get the same amount of green in cyan and yellow I need to remove some green from cyan and remove green/add red from/to yellow.

Related to this question, what does it mean if the flashing boxes never disappear? For example, when using the blue bar pattern, the flashing completely disappears for both saturation/tint yet even though red's optimal tint setting is the same when viewing the red bars pattern, the flashing does not disappear.

Finally, if all of the above is indicative of the color points being off the SMTPE specs, how common is it for this to be fixed with IS&F calibration? Do modern sets allow for color management such as this?

thanks for any clues one can give me on this subject.

#2 of 6 Michael TLV

Michael TLV

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Posted February 10 2008 - 05:56 AM

Greetings

Answer ... it depends on the TV.

Blue filters also have their own issues and as such, can deliver wrong answers too. Your blue filter can look very different from the next person that buys the same disc.

A pro calibrator can only work with what the TV permits. He cannot re-engineer a TV ... certainly not for the typical $300 he gets paid. Re-engineering will cost you many $1000's.

The onus is then on you to buy the right TV set where even if it is not right out of the box, at least it has the ability to be adjusted correctly.

(Usually contacting a good calibrator can get you a number for potential TVs to look at.)

Regards
Michael @ The Laser Video Experience
THX Video Systems Instructor/ISF Instructor
Lion A/V Consultants Network - TLVEXP.com


#3 of 6 ThomasL

ThomasL

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Posted February 10 2008 - 06:30 AM

Thanks Michael for the reply.

The tv in question is a member of the Samsung LNT-xx61F LCD series.

I am curious if these models are tweakable by a pro with regard to such issues as I described. Overall, in reviews I've read recent Samsung LCDs seem to be fairly accurate with regard to color and color decoding - in general this does seem to be the case. First tv I've ever had that the settings are so close with both saturation and tint for all 3 color bar test patterns. But that is what got me thinking about exactly causes the differences.

I have noticed that Samsung includes a MyColor Control that allows one to tinker with pink, blue, green and white. I have not been able to find any satisfactory answer anywhere as to what these actually do. Blue and green don't seem to affect overall saturation of those colors at all according to the Avia II test patterns. White does have an effect - it alters your gray scale - which I guess in the right hands might be useful if you wanted to set overall tracking to Warm 1 and then tweak it - yet Samsung already has White Balance user controls that seem to accomplish the same thing. If anyone knows what these are supposed to do, I'd appreciate just knowing. Posted Image

Last interesting point regarding color filters, since I also own the original Avia and the new Avia II, I decided to see what was different if I viewed the blue bars pattern with dual filters - I did this because with one filter, my eyes see an awful lot of green leaking through. The difference is about 5 percent error on overall saturation and tint (the controls go from 0 to 100 - so I'm assuming a linear scale - i.e. 5 ticks difference). Interesting, I tried this same experiment with the red and green filters and there was no difference. While I know that some color leaking occurs with filters, I was a bit puzzled as to why only blue had this difference. If anyone has an explanation of this, I'd appreciate just knowing as well. Posted Image

cheers,


--tom

#4 of 6 Michael TLV

Michael TLV

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Posted February 10 2008 - 07:08 AM

Greetings

Not too many goodies in the typical service menu of the samsung LCD units. Just the grayscale stuff and brightness and contrast.

Most of the other stuff is further embedded in the TV in places sometimes called designer or engineering menus. Where design and marketing decisions are made. No one outside of Samsung would have access to that information.

Regards
Michael @ The Laser Video Experience
THX Video Systems Instructor/ISF Instructor
Lion A/V Consultants Network - TLVEXP.com


#5 of 6 ThomasL

ThomasL

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Posted February 10 2008 - 08:58 AM

Thanks very much Michael.

At some point, I would like to have the set's grayscale professionally calibrated for the HDMI inputs but at the moment, the funds are currently not allocated. It is nice that they have included both cuts/drives in the user menu in order to do this though. Overall, I'd say this Samsung set can look fairly nice just by using some of the Avia test patterns and a bit of basic knowledge on how to use them.

cheers,


--tom

#6 of 6 Allan Jayne

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Posted February 13 2008 - 02:02 AM

Quote:
Originally Posted by ThomasL
Last interesting point regarding color filters, since I also own the original Avia and the new Avia II, I decided to see what was different if I viewed the blue bars pattern with dual filters - I did this because with one filter, my eyes see an awful lot of green leaking through. The difference is about 5 percent error on overall saturation and tint (the controls go from 0 to 100 - so I'm assuming a linear scale - i.e. 5 ticks difference). Interesting, I tried this same experiment with the red and green filters and there was no difference. While I know that some color leaking occurs with filters, I was a bit puzzled as to why only blue had this difference. If anyone has an explanation of this, I'd appreciate just knowing as well.
Don't forget the "fraction of a fraction" effect.

If one layer of blue filter lets through 90% of the blue and 20% of the green, then two layers of the same blue filter will let through 90% of 90% (equals 81%) of the blue and 20% of 20% (equals 4%) of the green. The proportion is vastly changed. So you will notice a different behavior with two layers. Meanwhile if your green filter was more selective to begin with (i.e. the amount of red and blue let through was negligible relative to the green) then a second layer won't give a visible difference.

Video hints: Video Technicalia Made Easy
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