Latest post Sat, Feb 2 2019 8:18 PM by David Yardley. 28 replies.
Page 2 of 2 (29 items) < Previous 1 2
Sort Posts: Previous Next
  • Wed, Mar 21 2018 9:01 PM In reply to

    • jef
    • Top 50 Contributor
    • Joined on Sun, Feb 26 2006
    • Maryland
    • Posts 3,375
    • Points 40,765

    Re: Slog3-Cine3 to LC709 with Symphony.

    Gretski:

    Correct me if I'm wrong but I believe a LUT must be applied before any correction because it is designed to reverse the slog curve from the camera. If correction is applied first, correction curves will not work as designed.

    If the LUT is applied first and the camera is using the full range of Slog it WILL clip the highlights / lowlights. Because of the signal processing, Symphony cannot  recover those clipped values, the information is lost.

     

    A common technique for colorists working in Resolve is to use a "pre correct" node before a LUT node to recover highlites or lowlites that might be clipped by the LUT.

    One limitation of a LUT in either Avid or Resolve is that it can clip info and that info will not be recoverable after the LUT.  Hence the pre correct.  Resolve has now implemented a different method of doing what LUTs would do (called color transforms I believe) which do NOT clip the info.

    To experiment, take a LOG clip with no LUT, and on the layer above put the correct LUT.  Now add a color correction to the LOG clip and mess with levels only (curves is a good place).  Push to hard and you should see clipping.  And on some clips pulling down the level may reveal detail that previously had been lost.

    Jef

    Avid DS 11.0.2 R.I.P | MC "Well, it depends ..." mostly 8.10.0 but playing w 2018.11| OS 10.11.x - various MacPro Towers - home system MacPro... [view my complete system specs]

    _____________________________________________

    Jef Huey

    Senior Editor

    Old Stuff  http://vimeo.com/album/3037796

  • Wed, Mar 21 2018 11:21 PM In reply to

    Re: Slog3-Cine3 to LC709 with Symphony.

    jef:
    Resolve has now implemented a different method of doing what LUTs would do (called color transforms I believe) which do NOT clip the info.
    If you are interested in this Here is a Link to an informative tutorial explaining Resolve Colour Management. How and why (it is better than using LUT's) to use RCM when converting a wide range of camera formatc media to timeline output formats (Rec 709, DCI-P3 etc).

  • Thu, Mar 22 2018 9:05 AM In reply to

    Re: Slog3-Cine3 to LC709 with Symphony.

    Gretski:

    Correct me if I'm wrong but I believe a LUT must be applied before any correction because it is designed to reverse the slog curve from the camera. If correction is applied first, correction curves will not work as designed.

    If the LUT is applied first and the camera is using the full range of Slog it WILL clip the highlights / lowlights. Because of the signal processing, Symphony cannot  recover those clipped values, the information is lost.

     

     

    If you apply the reverse LUT without any pre correction you lose the ability to gain from the additional latitude the LUT was used to achieve.

     

    Its important to know what a LUT is used for. Normally its to extend the latitude of the camera and to increase the bit depth of important exposure areas to the detriment of less important areas (hence why moving to sub 10bit codecs later will produce banding)

    To gain from that the camera operator has to expose correctly or the increased range isn't used and its just lose lose.

    Used correctly and exposed to use the expanded range you will need to pre grade to decide how to mange that increased range in the limited delivery range. If you just apply the LUT you undo all that. May as well not have used it.

    So a pregrade of the footage to manage the latitude then apply the LUt or grade to achive that result. Then normal grading.

     

     

    ACI Moderator. I'm not employed by Avid or work for them. I just do this in my spare time. Normally using the current Media Composer version on My... [view my complete system specs]

     

    Broadcast & Post Production Consultant / Trainer  VET

     

    T 07581 201248 | E pat@vet.co.uk | W www.vet.co.uk |


    Media Composer V8.2 Review Background Render

    -

    Follow me on Twitter Pat_H_VET

  • Mon, Dec 10 2018 6:42 PM In reply to

    • DIESELE
    • Top 100 Contributor
    • Joined on Mon, Apr 28 2008
    • Cymru/Wales
    • Posts 1,071
    • Points 13,220

    Re: Slog3-Cine3 to LC709 with Symphony.

    Thast pretty clear Pat.  Thanks.

    I tried my first proper Slog edit with a source based Slog2 to 709 LUT but this did terrible things to the images which threw me as surely it should just be the equal but opposite of Slog and just bring it back into normal 709 territory?  What it was doing was bonkers though. Whats this function even for then?

    So I removed the LUT and graded manually - time consuming but looks fine.  I just thought that Slog was very different to non log shooting - different matrix paramaters and colourspace etc but I seemed to grade it in Symphony and looks OK to the eye.

    I get the principle of SLog being designed to handle highlights better and thuis give increased dynamic range, but seriously I dont really get the advantage over shooting HyperGamma 4 (my favouritre for daytime - and I use HG7 or plain REC709 for night as log is totally unsuitable).  HG4 is a breeze to grade and is 900% the latitude of 709.  Log is 1200% - not worth it given this utter grading pain in Avid - all the blacks had to be dialed in shot by shot!  I suggest Slog is better graded on different more suited kit - but I hate the regressive notion of roundtripping. HG4 and Symphony is my combo :)

    Cheers

    Symphony 2018.11, Blackmagic Intensity Pro (cant get it working well in 4k though for client monitor - which was the point...), WIN 10 on 2000Mbps M.2 SSD, Nvidia Quadro K2000, Asus X99 Mobo, 4.0 GHz Hex core CPU, 32Gb 2800 Mhz RAM, WD Black 8Tb RAID10

    VIDEO MEDIA PRODUCTION COMPANY AND FACILITIES CARDIFF, LONDON, BRISTOL, WALES, CRACKING PRODUCTIONS

     

  • Tue, Dec 11 2018 4:58 PM In reply to

    Re: Slog3-Cine3 to LC709 with Symphony.

    What would be really good is some bars from the camera that have gone through the camera LUT processing so they can be viewed in a scope and tweaked accordingly at ingest.  I don't know of any cameras that have this facility.

    MC/SN 2018.6+7+8+9+12 x 16 Z400/420/440 PC's on W7 x64. 2 x Mac, 4 x PT 12.8.1 HDX, S6 all on PCs. ISIS 5000 X 2. [view my complete system specs]
  • Tue, Dec 11 2018 5:43 PM In reply to

    • DIESELE
    • Top 100 Contributor
    • Joined on Mon, Apr 28 2008
    • Cymru/Wales
    • Posts 1,071
    • Points 13,220

    Re: Slog3-Cine3 to LC709 with Symphony.

    Great point.  I guess this is why you can shoot the ColourChecker Card.

    The footage I struggled with looks fine using the Catalyst Brows LUTs - it auto assignes one and it looks great.  None of the issues of the Avid Slog 2 LUTS...  The thick plottens!

    Symphony 2018.11, Blackmagic Intensity Pro (cant get it working well in 4k though for client monitor - which was the point...), WIN 10 on 2000Mbps M.2 SSD, Nvidia Quadro K2000, Asus X99 Mobo, 4.0 GHz Hex core CPU, 32Gb 2800 Mhz RAM, WD Black 8Tb RAID10

    VIDEO MEDIA PRODUCTION COMPANY AND FACILITIES CARDIFF, LONDON, BRISTOL, WALES, CRACKING PRODUCTIONS

     

  • Tue, Dec 11 2018 5:51 PM In reply to

    • jef
    • Top 50 Contributor
    • Joined on Sun, Feb 26 2006
    • Maryland
    • Posts 3,375
    • Points 40,765

    Re: Slog3-Cine3 to LC709 with Symphony.

    DIESELE:

    The footage I struggled with looks fine using the Catalyst Brows LUTs - it auto assignes one and it looks great.  None of the issues of the Avid Slog 2 LUTS...  The thick plottens!

    So dig around the Sony Catalyst and find the LUT used, copy into the Avid Color Management world and try it.

    There have been issues and changes about Avid's handling of LUTs through the versions.

    Jef

    Avid DS 11.0.2 R.I.P | MC "Well, it depends ..." mostly 8.10.0 but playing w 2018.11| OS 10.11.x - various MacPro Towers - home system MacPro... [view my complete system specs]

    _____________________________________________

    Jef Huey

    Senior Editor

    Old Stuff  http://vimeo.com/album/3037796

  • Wed, Jan 30 2019 11:40 AM In reply to

    Re: Slog3-Cine3 to LC709 with Symphony.

    Pat Horridge:

    Its important to know what a LUT is used for. Normally its to extend the latitude of the camera and to increase the bit depth of important exposure areas to the detriment of less important areas (hence why moving to sub 10bit codecs later will produce banding)

    I wouldn't say that.  LUT is used to conform from one colorspace to another by looking up the values in the source colorspace and correcting them to look correct in the target colorspace. Ie. if I am recording in an S-LOG colorspace (usually overexposing and stealing range from the highlights) then I want make sure that I can use the extra info in the bottom end of the range later. Pulling the image down in CC, reduces the noise in the shadows - and I can do that from the LOG with no LUT.

    My original question was if values can possibly be accessible PRE lut. I never found them to be, and over exposed highlights that are possibly blown out by the LUT cannot be fixed - so I have to remove the LUT (which is what I do) and then just grade using scopes and a REC709 monitor etc.

    If you are using LUTs in the camera or monitor on set and exposing / lighting to get a certain look, then the workflow will be different, but standard colorspace conversion by the LUT should be possible to access / bypass pre lut in any serious grading software. 

    I suppose it is here too, but it's just not as accessible as I would like.

     

    As per Avid on my avid machines. [view my complete system specs]
  • Thu, Jan 31 2019 10:38 AM In reply to

    • DIESELE
    • Top 100 Contributor
    • Joined on Mon, Apr 28 2008
    • Cymru/Wales
    • Posts 1,071
    • Points 13,220

    Re: Slog3-Cine3 to LC709 with Symphony.

    I think I agree with that - if the LUT blows it and makes the highlights clip then reducing the luminance afterwards say in your curves graphs, doesnt bring the clipped highlights back.  To get them back properly you have to remove the LUT and grade manually, preserving the highlights by eye and without a LUT.

    Symphony 2018.11, Blackmagic Intensity Pro (cant get it working well in 4k though for client monitor - which was the point...), WIN 10 on 2000Mbps M.2 SSD, Nvidia Quadro K2000, Asus X99 Mobo, 4.0 GHz Hex core CPU, 32Gb 2800 Mhz RAM, WD Black 8Tb RAID10

    VIDEO MEDIA PRODUCTION COMPANY AND FACILITIES CARDIFF, LONDON, BRISTOL, WALES, CRACKING PRODUCTIONS

     

  • Thu, Jan 31 2019 11:44 AM In reply to

    Re: Slog3-Cine3 to LC709 with Symphony.

    Gretski:

    Correct me if I'm wrong but I believe a LUT must be applied before any correction because it is designed to reverse the slog curve from the camera. If correction is applied first, correction curves will not work as designed.

    If the LUT is applied first and the camera is using the full range of Slog it WILL clip the highlights / lowlights. Because of the signal processing, Symphony cannot  recover those clipped values, the information is lost.

     

    If you just apply the LUT the end result negates apply the LUT at all. The LUT allows a greater dynamic range to be recorded and to access that wider range and which part of it you want to retain you need to correct before the LUT.

    So yes most content shot with a LUT applied has that LUT reversed for no gain. But use a LUT correctly togather a wider dynamic range and you have more scope in the grade. You lose that scope if the LUT is applied at source.

     

    ACI Moderator. I'm not employed by Avid or work for them. I just do this in my spare time. Normally using the current Media Composer version on My... [view my complete system specs]

     

    Broadcast & Post Production Consultant / Trainer  VET

     

    T 07581 201248 | E pat@vet.co.uk | W www.vet.co.uk |


    Media Composer V8.2 Review Background Render

    -

    Follow me on Twitter Pat_H_VET

  • Thu, Jan 31 2019 11:57 AM In reply to

    • DIESELE
    • Top 100 Contributor
    • Joined on Mon, Apr 28 2008
    • Cymru/Wales
    • Posts 1,071
    • Points 13,220

    Re: Slog3-Cine3 to LC709 with Symphony.

    ?  Pat you talking about a burnt in LUT?  That is, camera shoots Log, which gives the sensor greater dynamic range, but then immediately apply a blanket LUT to the recorded file that limits the post grading, but may give better looking pics than shooting straight 709.  

    I tend to shoot Sony HG4 which is a halfway house - gives far better results than 709 but without the drawbacks of Log - both in camera (limits many things such as Viewfinder LUT on an FS7 when shooting off-speed for eg) and the extra post that Avid is still not fully friendly with in the way that Resolve  might be (for eg).

    Symphony 2018.11, Blackmagic Intensity Pro (cant get it working well in 4k though for client monitor - which was the point...), WIN 10 on 2000Mbps M.2 SSD, Nvidia Quadro K2000, Asus X99 Mobo, 4.0 GHz Hex core CPU, 32Gb 2800 Mhz RAM, WD Black 8Tb RAID10

    VIDEO MEDIA PRODUCTION COMPANY AND FACILITIES CARDIFF, LONDON, BRISTOL, WALES, CRACKING PRODUCTIONS

     

  • Thu, Jan 31 2019 7:34 PM In reply to

    • Gretski
    • Not Ranked
    • Joined on Thu, Oct 13 2005
    • Posts 177
    • Points 2,375

    Re: Slog3-Cine3 to LC709 with Symphony.

    And that is the whole thrust of the discussion.  If you apply the lut as the first process in post (as you should do to match the curves) Avid locks it in and does not allow  you to recover burnt highlights.

    You then end up throwing the lut away and eyeballing the correction through curves etc.

    This is very unsatisfactory as you have to crudely mimic the complex Mathematical curve of the lut.

    You can now put the lut on the track above the correction which is much better but not perfect.

    In an ideal world the lut would be applied within the symphony colour correction allowing recovery of highlights etc

    Asus X299, i7 7820, Nvidia 2000M 32GB ram, NVME SSD 8.9.1 ( yes its very fast!) [view my complete system specs]
  • Sat, Feb 2 2019 3:04 PM In reply to

    • jef
    • Top 50 Contributor
    • Joined on Sun, Feb 26 2006
    • Maryland
    • Posts 3,375
    • Points 40,765

    Re: Slog3-Cine3 to LC709 with Symphony.

    Gretski:

    In an ideal world the lut would be applied within the symphony colour correction allowing recovery of highlights etc

    Not to be a nit picker, but terms are important.  A LUT, by the way it works, will clip values.  So just having it in Symphony CC will not help.  What is needed is what was discussed about the Resolve (and Baselight) world - a color transform.  This does what the LUT does (apply specific curves) but does NOT clip values.

    But to take advantage of that type of tool, the whole color corrector engine must be working in Float values.  Symphony is not.  Floating value math is what allows levels that seem to be clipped to be recovered.  An explanation of this is beyond this thread.

    I would be surprised if Symphony CC is updated to such a tool.

    Jef

    Avid DS 11.0.2 R.I.P | MC "Well, it depends ..." mostly 8.10.0 but playing w 2018.11| OS 10.11.x - various MacPro Towers - home system MacPro... [view my complete system specs]

    _____________________________________________

    Jef Huey

    Senior Editor

    Old Stuff  http://vimeo.com/album/3037796

  • Sat, Feb 2 2019 8:18 PM In reply to

    Re: Slog3-Cine3 to LC709 with Symphony.

    jef:
    But to take advantage of that type of tool, the whole color corrector engine must be working in Float values.  Symphony is not.

    Herein lies the problem. The MC pipeline allows huge amounts of headroom at top and bottom and the colour transformations (and Luts) work in 16 bit as Avid has proudly proclaimed. You can seee this by stacking up Avid Luts and seeing that reversing them regains the original waveform.

    Of course the whole point of using Luts is to give grteater control in colour grading.

    Hey we can now easily add a mask and recover those highlights through that window!

    But the color corrector in MC works in 12 bit and clips outside 1-254...

     

     

    Symphony 7.06 OS 10.9.5 QT 7.6.3 Mac Pro 2x2.66 6-core 32GB Ram Aja Kona 3. MC 7.0.6 OS 10.9.5 Mac Pro 5.1 2x2.97 6-core 14GB ram Aja I/O express, Apple... [view my complete system specs]
Page 2 of 2 (29 items) < Previous 1 2

© Copyright 2011 Avid Technology, Inc.  Terms of Use |  Privacy Policy |  Site Map |  Find a Reseller