Orash Rahnema

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Posts posted by Orash Rahnema

  1. 22 hours ago, Thomas Singh said:

    It behaves totally different when you drag the line down, try for yourself. 

    Can it be that hue vs Sat works on HSL or some different colour space rhater then the rgb colour space that Sat use.

    I belive Sat control works in RGB using 709 primaries, not sure about curves, the same nature of them makes me believe they are in hsl.

    But then again i might be wrong :)

    would be interesting to check

  2. Hi David

    there are few things that should be known before giving a proper answer.

    the only thing contaminated are the black bars or does the image looks more contrasty on your display?

    a quick things that come in mind is, when the image are desqueeze, the black bars you see are black to start with, but if you really push the level you see that behave like they are part of the image, so if you "pollute" the black with a color cast or the blacks are lifted also the bars will be

    The solution would be to blank the frame using output sizing or timeline blanking

    that if there are not other problems that I can't see with the info we have.





    • Like 2

  3. Last year I have done a 15 min long short movie, shot on a single long take at sunset hour where the 4 subjects kept going in and out a house, so lots of exteriors and interiors with a massive light change.

    The DP i have worked with had done a great job "shutter pulling" and that helps a great deal.

    First thing I have studied how the light was changing and I found a  "master shot", then I have found all the places where I could hide the dynamics  and balance the whole thing with very simple correction, mostly offset and contrast working with the light changing and not going against it.

    I have used the layer mixer and create stream for each change I needed

    Then I have worked on the "look" and placed it within the single streams, to use the dynamics I have done before

    I have done a general correction after everything also.

    After all this I have worked with masks and stuff.

    The key is to keep it as simple as you can, things can become messy quite quick.

    try to brake it into smaller problems and think it like a multi shot video, that rather to have cuts have  dynamics.

    Choose if you want a massive node tree with a layer mixer like a did or to brake the cut in editing using cross dissolve. I don't like that approach as I rather move keyframes that to jump within cuts and fix dissolves.

    I hope I was clear enough :)

    • Like 2

  4. no really really sure what you are asking, but using a lut in aces is not a straight forward thing to do and generally not a good idea.

    you can try to make it work using lightspace but still it's a workaround that introduce many unpredictable factor and can give you nasty artefacts.

    Most of all if you want to go from an sdr odt to an hdr

    The lut will clip at 100 nits anyway so it's not going to work

    To go from an sdr to hdr there are not workaround (not like a trim dolby vision trim that take you from hdr to sdr)

    The only safe way is to grade it for hdr starting from what you already have, after the lut.

    in that way you can extend the contrast letting only the very highlight to go above 100nits and keeping most of the signal at a 100 nits where already belong. Also you will have more room to give shadow details, which is really nice.





  5. Red can read cube, as far as I remember, Alexa can't. 

    For the Alexa, depending on the model you have to use, on the Alexa xt you can only use a 1d lut and matrix and if I can recall the format is. Xml. 

    On Alexa mini, Amira, lf and basically all the arri camera after the Amira you can use a 3d lut and the format is. Aml

    I never had problem with a 33*33 lut but since you have to convert your cube lut into an aml you better reduce it to 17*17

    I use lattice to convert the cube into the aml. 

  6. Hi Michael

    if the lut is placed in the "3d video monitor output" should not give you any problems as it "should" work post ODT.
    I might be wrong here tho, maybe its not post odt even if sounds very strange.


    To make a 3d lut working in aces your best bet would be to use lightspace, @Steve Shaw can really help you out here.

    Check https://www.lightillusion.com/aces_manual.html under "CONVERTING LUTS INTO ACES" section.

    Lastly, the monitor calibration does have not to be different if you work in aces or unmanaged, since your monitor will still be a 709 monitor.

    In aces by choosing the ODT you transform from the aces color space to the choosen one (709 for example) and you have to monitor on the same colorspace you choose with the odt

    I hope it make sense





  7. Hi Michael

    the problem is where you are placing your lut, most likely

    in aces a "normal" lut cannot be used within the node tree, you either convert it to an aces lut, which is not as simple as it said,

    Otherwise  since it is a monitor calibration lut I would suggest it to load it to the "3d video monitor output" in the color managment tab (that should come after the odt, so should not create problems) or straight into the monitor.

    hope that helps you


  8. Hi all! 

    I'm planning to buy a mini panel and currently bm is giving (in Italy) a 10% discount. 

    It's not a lot, but still isn't bad.

    Anyway, are there any rumors of a new panel announced after nab? 



  9. Hi all! 

    It's now a couple of months that I have set up my windows workstation. 

    So far everything it's fine, in still getting used to few things but it's running smooth. 

    I'm finding few bugs here and there and I wanted to check was my problem or it's a common issue. 

    For example :

    In the deliver page, choosing a render folder, when i right click in the explorer/finder window to create a new folder, DaVinci crashes. 

    Once reopened it doesnt happen no more. 

    Anyone else has this problem? 




    • Like 1

  10. Hi!

    I have just tested my new pc with a gtx 1080Ti and trying to export a red clip 8K with a noise reduce I got two errors:

     "The GPU failed to perform image processing because of an error" "Error Code: 33."

     "The GPU failed to perform image processing because of an error" "Error Code: 77."

    I'm using Resolve

    If I disable in the preferences "use GPU for RED debayer" I don't get the errors but of course it slows down quite a lot

    Did anyone found a solution for it?




  11. I'm not really a "happy new year" guy but I wanted to take this chache to thank the people behind this forum and the users involved. 

    I have to say lowepost has become a great resource of information and I'm thankful of the help, tips and tricks and info I found here.

    So I wish to this forum and the users a great new year, full of nice info, tutorial and insights. 

    • Like 2

  12. With this estimate time is taken into consideration the "needs" of dop and director or are this "maximum" timing given by budget/production

    I work with a dop (that I really like and we have great relationship) that is not easy to work with, he just doesn't want to stop. 

    He could work on a grade for a whole year if someone doesn't stop him, and I cannot always do that.

  13. Hi all,

    I might have to lend my monitor to another colourist.

    Do you know if is there a way to password/pin lock it so no changes can be made at all?

    I have looked through out the manual and checked other forum but I haven't found the answer i need






  14. Hi all!

    in the colour lounge facebook group a pretty interesting topic was recently diccessed.

    Something that cought my eye was this post from Walter Volpatto.

    I'm not sure if he's part of this forum, here it is:


    In big productions, you almost NEVER stylized a grade: you rely entirely on the set lighting. 

    Of course I could have asked him but I thought it could be useful to discuss it here.

    I'd love to know what's your thought and experience on this. 

    When I see movies that have a very define style, other then art direction, styling and lighting, grading wise are there look created specifically for the show?
    this looks are created by whom? colour scientist + colourist and dops prior the shooting or at the first grading sessions? 
    This looks do they come to the grading room in a LUT form or luts are generally avoided in order to preserve the whole signal and avoid artefacts?

    Well, as usual way too many questions :)




  15. Thanks Bruno. 

    In lightillusion website says:


    Operating System: Windows 7/8/10 
    PC Requirements: Minimal - 2Gig Ram Laptop, with HDMI 
    Mac Operation: Runs on Mac using any Windows Emulation 


    Unfortunatelly the first laptop i tried Met this requirement. 

    Probably It was that laptop's fault anyway. 

    I should try with another One running anche i5 CPU and see if It works