IRE settings

vhelp · ..Semi Neutral.. Joined: 31 Mar 2001 Location: New York

Now this is what I was searching for in a filter. What got me started
on the idea (you beat me too it, Vegas Man) was the iLO. I've pointed
some thread on sample pics in other areas (can't remember them at this
time though) and I was thinking on a form of color shift somewhere's,
but I couldn't put my finger on it.

But, now that you have found (or seemed to, needs to be verified) if
you can figure out the formula/equation for this (probably has something
to do within the YUV -> RGB formula) we could apply it into a filter
that we could use.

Building on this idea (edDV 's latest color shift findings) I would
like to simulate it in a tool that I am working on in delphi.

@ edDV

Do you know so far, what is needed to build the formula, so that I
could try my hand at emplementing it in my tool ??

EDITED:
I was thinking that this could be applied to other varation in the IRE
levels of other equipments, and create templates for each item that
shifts the IRE.

Thanks,
-vhelp 3537
_________________

VHELP's - Sample Clips [last: 12.29.06],
my YouTube videos

edDV · Posted: Aug 24, 2005 19:36

The normal "washed out" NTSC capture problem is caused by 7.5 IRE black being mapped to level digital level 32.

I know nothing about the green shift problem on the Panasonic. Do you have any links?
_________________
Recommends: Kiva.org - Loans that change lives.
http://www.kiva.org/about

vhelp · ..Semi Neutral.. Joined: 31 Mar 2001 Location: New York

If the question was directed at me, no.. I don't know of any links.
Less you ment for Cyrax9 's post here, here and here.

-vhelp 3539
_________________

VHELP's - Sample Clips [last: 12.29.06],
my YouTube videos

BJ_M · Patron Joined: 30 Jul 2002 Location: Canada

might be a timing issue --
_________________
"Each problem that I solved became a rule which served afterwards to solve other problems." - Rene Descartes (1596-1650)

edDV · Posted: Sep 29, 2005 15:58

vhelp · ..Semi Neutral.. Joined: 31 Mar 2001 Location: New York

In your last post, you said..

>> All I did was shift the Y levels down 7.5%. That shifted 7.5-107.5 IRE down to
>> 0-100 IRE for Y.

But, what is the notes on the "white" levels..

>> Other sources (e.g. VCR, laserdisc) might be scaled 7.5-100 IRE rather than
>> 7.5-107.5 IRE. In those cases, black needs to go down 7.5% but white (contrast)
>> also needs to be increased 7-8%. These luminance adjustments are independent of
>> chroma and hue.

But, I'm confused about the above % setup for "white" levels. What part of
the "Y" values are being black-leveled, then white-leveled ??
(I don't see how that is possible, when adjusting the "Y" levels for black,
then white)

I ask, because I want to duplicate this (in code) with a known image, and
then compare w/ your Vegas graph, to see if the levels fall exactly in place.

Thanks for your responses.

-vhelp 3600
_________________

VHELP's - Sample Clips [last: 12.29.06],
my YouTube videos

edDV · Posted: Oct 01, 2005 12:59

A waveform monitor is highly useful to sort this out. Depending on sources, the incoming video levels can be 7.5-100 IRE or like the cable box above 7.5-107.5 IRE. If the latter, all that is needed is a -7.5 IRE black level shift.

In the more general case the -7.5 IRE black level shift must be followed with a linear boost of Y gain to place whites up to 100IRE.

The Vegas Levels filter (Input Start setting) acts to stretch blacks down linearly without affecting white position. Input end setting stretches whites without affecting black.

I made this test pattern to show how it works. Left side is reference with 0,25,50,75 and 100IRE blocks. The Right side will have the filter applied.

Here I applied a -5%shift to black. Note that white stays put and gray levels shift down proportionately.

Here I applied a +5%shift to white. Note that black stays put and gray levels shift up proportionately.

Here I applied a -5%shift to black and +5%shift to white. In this case, 50% gray (50 IRE) stays put and white and black are stretched 5%.

_________________
Recommends: Kiva.org - Loans that change lives.
http://www.kiva.org/about

jamiemark · Member Joined: 15 May 2004 Location: Canada

For people who don't have the patience to read through all the technical mumbo-jumbo (like me), can someone list the brands of dvd recorders with the proper NTSC IRE setting. For those that don't, like Toshiba for example, how is the problem corrected (using on screen settings)? Simplest terms possible, please

gshelley61 · Frequent Flyer Joined: 19 May 2004 Location: USA

jamiemark · Member Joined: 15 May 2004 Location: Canada

Thanks for the info. So once and for all, is 0.0 or 7.5 the CORRECT IRE setting for North America??

gshelley61 · Frequent Flyer Joined: 19 May 2004 Location: USA

trhouse · Member Joined: 28 Aug 2003

The Sony GX315 and JVC DR-M10S have no black level adjustments and are both set up for IRE=0 sources so they produce slightly light images from IRE=7.5 sources like those mentioned above.

samijubal · Member Joined: 25 Jul 2004

Where do satellites figure into all this? I don't see any black level problems when I record. I gave up on cable a decade and a half ago or so.

gshelley61 · Frequent Flyer Joined: 19 May 2004 Location: USA

StuR · Member Joined: 19 Sep 2006 Location: United Kingdom

I've breifly scanned through this post as 'IRE errors' is a subject thats come up during DVDRW reviews and now I've noticed the sticky.
Can someone please tell me that it's not an issue for PAL systems (in the UK), please so I can have one less thing to think about

.

edDV · Posted: Apr 05, 2007 11:02

StuR · Member Joined: 19 Sep 2006 Location: United Kingdom

woo hoo. Thanks.
So... PAL home vhs>DVD will not give IRE errors, and all this talk of IRE errors in dvd recorders like JVC's, Toshiba and Pioneer can be ignored as it's a US (NTSC) problem. Strange that Toshiba allow input brightness adjust, and Pioneer Black/White levels adj. not mentioning Sat/Hue.
Do I take it this is a little bonus feature and not crucial. Firsts rec. was Philips DVDR3305 which over brightned incoming signal (even best Q. RGB scart) so thought this was an issue.
Current rec. - Sony GX300 - balance O.K. but made sure it could be adjusted.