Latest post Thu, Jun 11 2020 3:44 PM by Mercer. 7 replies.
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  • Wed, Jun 10 2020 5:08 PM

    Color Transformation, Color Space, Name columns ; Linked & Legacy

    Hi, If I am in an HD Rec 709 Project and I Legacy Import a JPG believed to be Full Range, the Bin Column for Color Space shows "Rec.709 [video levels]" whether I had used Import Settings>Image>Color Levels> Do not Modify, treat as legal range -OR- Scale from full range to legal range. When I look at the Color Transformation Bin Column for those two legacy imports, there is no data (it's blank).

    When I Link to the same .jpg, the Color Space column reads "Rec.709 [full range] and the Color Transformation column reads:

    "Levels scaling (full range to video levels)"

    Question: Is there a bin heading, tool, feature or trick to verify the original color space of a Legacy-imported file? 
    And when I do have access to a file, then Link to it, does that Color Transformation column data indicate the file's original Color Space? 

    In the example above, would Color Transformation data be different if the jpg file or any file was already Rec.709 [video level]? I do see that .mxf graphic files I had Legacy-imported are showing: "[video kevels]" only. No "Rec.709" preceding it.

    Re Name column. I also noticed that if I change the name of a Link Masterclip in my bin, even if I delete that masterclip and remove it from any Sequence, the next time I link to the same file, it shows up in Bin with the last changed Name I used. Is there a way to have Source Browser deliver that file like it did initially, using the file name.jpg ? Am I required to refresh a database to do it and if so, how is that done on demand?

    Thanks for any input.

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  • Wed, Jun 10 2020 6:48 PM In reply to

    • jef
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    Re: Color Transformation, Color Space, Name columns ; Linked & Legacy

    Telegram!:

    In the example above, would Color Transformation data be different if the jpg file or any file was already Rec.709 [video level]? I do see that .mxf graphic files I had Legacy-imported are showing: "[video kevels]" only. No "Rec.709" preceding it.

    All really good questions. I have been frustrated by some of these as well.

    For the quoted question above I would think that any JPEG will always be presumed to be RGB (full) levels as that is what the standard is for that file type.  Just because us wacky TV types don't want to use all the bits is our problem.  Big Smile  And I have never seen any discussion of a metadata tag for still files to do otherwise.  But I am probably wrong.

    Jef

    Avid DS 11.0.2 R.I.P | MC "Well, it depends ..." mostly 8.12.9|OS 10.14.x - iMac Pro 2019 - home system MacPro Dual 2.8 8core GTX680 "Harpertown"... [view my complete system specs]

    _____________________________________________

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  • Wed, Jun 10 2020 9:35 PM In reply to

    Re: Color Transformation, Color Space, Name columns ; Linked & Legacy

    Thanks for that info, Jef. Supporting File's  Test Patterns  > 1080 HD has tifs like SMPTE_BARS.tif that initially link and show in Color Space as just ["full range]", but then becomes in Color Space as "Rec.709 [full range]" after the Source Browser plug-in is manually switched with AutoDetect or (was it?) after I accessed the linked masterclip for the first time in Source Settings. No sign of just [full range] in SB, except back in Source Browser, looking at the data in other HD 1080 tifs that I did not access. Has something to do with QuickTime and/or a default.

    I should read the manual, but is there a way to auto-refresh the SB Directory? Or are we expected to right-Click initially on every SB link candidate?

    I wanted to see what that full range SMPTE_BARS.tif linked masterclip looked like on the Color Correction Y-Waveform, but no matter which of the labeled Rec.709 Color Adapters was applied in SB, I didn't see what I would call a Full Waveform with the blackest bar at 0 zero and next darkest at around 7.5 and the whitest at or above 100. I did refresh the Sequence. I had to use CC's auto-contrast button on the linked masterclip in a Sequence to get that "full" look on the Composer monitor and the Y-Waveform. I feel I must be missing something here, and that it may have something to do with NOT using the QuickTime AMA plug-in on the tif in SB, before I made the revised Linked masterclip. I gotta go back and try using QuickTime, to see how it appears.  

    A lot to learn. and this is on v2018... 

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  • Thu, Jun 11 2020 9:23 AM In reply to

    • Mercer
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    Re: Color Transformation, Color Space, Name columns ; Linked & Legacy

    If you import the included colour bars from the test pattern folder, @100% and 75%, you will see on the vectorscope, which is really what you should be looking at for bars, that 100% aligns with the outer boxes and 75% with the inner ones. As long as you have unmodified levels by treating the import as a legal one. Accurate colour bars therefore should not deviate as long as you don't scale full range to legal.

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  • Thu, Jun 11 2020 10:42 AM In reply to

    Re: Color Transformation, Color Space, Name columns ; Linked & Legacy

    Thanks again, Mercer. It's a lot (for me) to take in. I'm re-reading this great PDF doc,  http://www.jobterburg.nl/Publications/601_709_RGB.pdf  and these concepts are finally beginning to make sense. Its uses Y-waveform examples, which I find are easy to follow. 

    And I'm figuring you are expert, with a 30k Monitor at your disposal, etc. and that everything you offer is just as correct and best practice. I have yet to do my Legacy Imports on the HD 1080 SMPTE_BARS.tif inside Supporting folder. Will be doing that later today, but:

    I was curious what is happening in terms of levels after making a linked masterclip, using both the choice of Avid generic and/or QuickTime plug-ins. As I tried to describe above, the initial masterclip said only "[full range]", but it changed all by itself either when I opened Source Settings or when I returned to Source Browser and right-clicked on the file and specifically avoided using QuickTime by choosing Auto-Detect, which engaged Avid generic.

    Back to the VectorScope view... it seems that you may be indicating that 100% and 75% are related to particular bars, if so which ones? The two whitest or ???

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  • Thu, Jun 11 2020 1:36 PM In reply to

    • Mercer
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    Re: Color Transformation, Color Space, Name columns ; Linked & Legacy

    Telegram!:

    And I'm figuring you are expert, with a 30k Monitor at your disposal, etc. and that everything you offer is just as correct and best practice. I have yet to do my Legacy Imports on the HD 1080 SMPTE_BARS.tif inside Supporting folder. Will be doing that later today, but:

    Big Smile I wish I had such money. I have a good HD grading monitor but it cost no where near that price, thankfully.

    I think you are over-thinking this slightly.  Levels refer to RGB or IRE legal so 100% white would be 235,235,235 rgb 8 bit or 100ire and 75% white = 180, 180, 180 rgb 8bit 75ire. Black is 16,16,16 for both. Ama linking shouldn't affect those - only if you choose to scale and not treat as legal. Since most cameras use logs etc. these days and it is common practice to shoot a colorchecker chart rather than generate bars in camera, it shouldn't matter, as long as you use the correct lut and grade in the correct legal space. Your color bars are only for line up with your exported master and there you need to ensure they are both a) true and b) you have not modified them upon import.

    Edit: What I mean to say is don't AMA link colour bars, import them, treated as legal and unmodified, from the provided folder.

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  • Thu, Jun 11 2020 3:03 PM In reply to

    Re: Color Transformation, Color Space, Name columns ; Linked & Legacy

    Thanks for replying. I do agree with Legacy Import, for those Test files, and have always used them as you described. I chose to AMA/Link SMPTE_BARS because I felt I was familiar with what it would look like or should look like, on the Y-Waveform view. I am not an old hand with AMA/Linking but I am not lost either. I want to extrapolate from what happens to Bars, what will happen on varieties of camera, graphics, Avid-exported files, some "full range", others "Rec.709 [full range]", or "Rec.709 [video levels]" 

    It seems Source Browser permits a "link with" option that changes the Plug-in used. It also seems that the linked masterclip is changeable in Source Settings, in terms of Color Space, from "video levels", or "Rec.709 [video levels]", "Rec.709 [full range]", and many more. What I noticed is that if I choose the QuickTime option in SB, the resulting masterclip can be changed in Source Settings. But if I had selected "Avid Generic", it arrives in bin as "Rec.709 [full range]", but there is no sign of the "[full range]" Color Transformation in the Source Color Space drop-down list in Source Settings.

    A bit of a curiosity I guess..Well, that's my Color question today, among too many.

    Squeeze v11 EOL-Pro Sony BM2100 Telecine with variable speed controller Casio VL-Tone, CZ-101, LCD watch AJA i/o Express with Express Card Slot Ignite... [view my complete system specs]
  • Thu, Jun 11 2020 3:44 PM In reply to

    • Mercer
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    • Joined on Thu, Apr 15 2010
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    Re: Color Transformation, Color Space, Name columns ; Linked & Legacy

    I don't see the point in linking to SMPTE bars, for your calibration, when to import them is a known quantitySmile. You call it legacy but import of a still takes microseconds and is still preferable to linking since it imports to the native working codec of Avid. If you have source material from eng cameras that predate lut/log workflows and you haven't time to import then yes I can understand. Again in this instance I would simply use the vectorscope to quickly line up the bars for a balancing colour grade, since that is what is was designed for, principally. This is unecessary with import so long as you treat as legal levels.

    Sorry if I've misunderstood you and you're just trying to ssee if there is a problem with AMA linking colour levels but for bars I just wouldn't trust that method.

    MC with Symphony option, 2020.4, HP ZBook 17 G5, i7-8850H 6 core/64GB ram/512 M2 ssd/Nvidia Quadro P3200/FHD, HP Thunderbolt Dock G2, BMD Ultrastudio Mini... [view my complete system specs]
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