This IS the Avid L2: [Avid-L2] Re: John's bars question from the expert...

Have to disagree Jeff. We very much still use color bars.

Color bars are actually much more useful now than they were 5 years ago. When everyone was using tape, the video levels were much more consistent.

Now that we are getting elements from so many different formats, the bars are critical to make sure color/gamma shift are not happening.

We get final color graded master files from the studios, and since we both have the same test pattern, we can be sure the episodes are being delivered without any color shifts.

Actually were running into a bunch of color shifts early on, but we were able to flag the problem and get the files redelivered in a different codec so we didn't have the color shifting problem anymore.

But that's just my experience.

-Peter

--- In Avid-L2@yahoogroups.com, "jeffsengpiehl" <jeffsengpiehl@...> wrote:
>
> but did anyone take a look at bars that had been through standards conversion? 1080-720, and vice versa? There's even MORE fun to be had there.
>
> Makes you realize that color bars are irrelevant in today's day and age, and they only exist on deliverables due to inertia. Punch in bars from your Deck's signal generator to your tape masters, and you've got a lot less to worry about then a QC flag for something no-one will ever use.
>
> JDS
>
> --- In Avid-L2@yahoogroups.com, "johnrobmoore" <bigfish@> wrote:
> >
> > Thanks for sharing with the L-2 group. If anyone would like to see the screen grabs and the actual files contact me off list and I'll send the same email to you that I did to Mr. Hullfish and others. I haven't had a chance to break out the calculator but it was obvious to me just using PhotoShop eye dropper that the I and Q RGB values were different in the various color bar files. Fun stuff for the nerd in me. Also I believe there is a debate over Union vs. NonUnion color bars in some circles. ;-) When I was in the unions I ended up in the bar every night. Now that I'm sober no bars at night and no union. Coincidence, Hmmmmmmmmmm. ;-(
> >
> > --- In Avid-L2@yahoogroups.com, Steve Hullfish <steve4lists@> wrote:
> > >
> > > A week or so ago, John Moore posted some links to some color bar examples from the web and from Avid and asked:
> > >
> > >
> > > I finally took a look at the Avid HD bars you mentioned and I do see the nice curly Q style of I and Q. I've included screen grabs off the Tek scope of 3 Bars The ARIB bars someone put up on the Avid L2, Smpte Bars of the 219 standard and Avid HD 1080 Bars. Interesting. I included the image files for each. So the challenge is which Steve H? Hullfish or Holmes will diagnose the image files and tell us how Avid got the math wrong for HD bars?. I'm betting it has something to do with the bigger stretch there is in HD bars as per one of the Tek seminairs. Here is what I've been told by Steven Holmes regarding 601 vs 709 bars. Could this be the reason Avid bars are off? Have they just repurposed SD bars?:
> > >
> > > The response is only coming THROUGH me, but it is indeed from the other Steve... Holmes, from Tektronix, with the answer:
> > >
> > >
> > > One thing we have to remember is that SMPTE Bars are a Composite color bar test pattern. I & Q do not exist in the Y Pb Pr or RGB domain.
> > > You cannot go as far negative as you need to reproduce proper I & Q with full White. I & Q fall outside of the Color space we have to work with they are a reference Composite phase vector not a color.
> > >
> > > I had one of my colleges look at the files also, and here is his response.
> > >
> > > [Non-text portions of this message have been removed]
> > >
> >
>