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Different node, different result??

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Danny Duchesneau
Different node, different result??
on Dec 17, 2012 at 11:10:21 pm

Hi,

I'm actually learning DaVinci Resolve Lite 9.0.4 and just found out a strange behaviour. Please have a look at the small video I did and let me know if this is a normal behaviour for Resolve...

https://dl.dropbox.com/u/5120911/davinciresolve/Lift.mp4

I find it "weird" that when I put a Lift value of -0.10 in the first node I don't get the same result as when I put that same value in the second node. Hope this is clear enough.

regards,

Danny


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Juan Salvo
Re: Different node, different result??
on Dec 17, 2012 at 11:24:12 pm

It's not very clear, but what is your source? The first node is making adjustment on whatever your source input is... the second is making adjustment on the 32bit float output of your first node.

Colorist | Online Editor | Post Super | VFX Artist | BD Author

http://JuanSalvo.com


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Danny Duchesneau
Re: Different node, different result??
on Dec 17, 2012 at 11:50:59 pm

The source is a QT from the DaVinci Resolve tutorials available on their website. Did you watch the video?
The video is showing me adding a Gamma value of 0.19 then a Lift value of -0.10. Now look at the viewer, what you see is result A, Gamma : 0.19 + Lift : -0.10 in ONE node. Then you see me resetting the Lift value to 0. At this point, the first node only has a Gamma value of 0.19. I am then adding a second serial node in order to put a Lift value of -0.10. Now look at the viewer, what you see is result B, Gamma : 0.19 + Lift : -0.10 in TWO nodes this time. why is the result different? I am use to 32bit float node base application since I've been doing compositing in Nuke for the last 5 years... If I was doing this in Nuke, the result of A and B would be the same.


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Dmitry Kitsov
Re: Different node, different result??
on Dec 18, 2012 at 1:10:48 am

In a video it is clearly visible that when you are making your adjustment you click with an eyedropper tool (thus qualifying the range of the node influence)in the shadows part of the image. Then, after you reset you adjustments and repeat them in a second node you did not click in the shadows areas of the image, and any adjustment you made then applied to the entire image.


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Danny Duchesneau
Re: Different node, different result??
on Dec 18, 2012 at 1:29:15 am

First, why is the eyedropper active by default?
Second, I'm just "mouseoverring" the viewer and not clicking at all as you would see some parts of the node turn to grey. I know that something is happening as I mouse over the viewer with the eyedropper but that's just the gamma value of 0.19 beeing applied couple of seconds later as I'm learning Resolve on a dual core laptop and it takes a couple of seconds for my computer to respond.


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Danny Duchesneau
Re: Different node, different result??
on Dec 18, 2012 at 1:36:25 am

My point is that the math should remain the same... Concatenation seems flaky...

Look when I do the same thing in an other package (Nuke);

https://dl.dropbox.com/u/5120911/davinciresolve/nuke.mp4

The result shouldn't change because I use two nodes instead of one to do the same thing isn't???


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Juan Salvo
Re: Different node, different result??
on Dec 18, 2012 at 4:54:55 am

No, the math is not the same. The first node is still performing a gamma lift. That sets the midpoint to the image. The next node in the pulling down the gamma lifted image. This changes. Each node is getting its input from the output of the last. So any manipulations in the node are burned into the image in the next. Including a gamma change. If you make no modifications in the first node and then perform any functions in the second node, it will behave the same as if it was in the first. Because there is no transformation on the image in the first node.

Colorist | Online Editor | Post Super | VFX Artist | BD Author

http://JuanSalvo.com


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Sascha Haber
Re: Different node, different result??
on Dec 18, 2012 at 3:02:20 pm

There is not concatenation because Resolve is fast enough to process a couple of nodes...unlike Nuke :)

A slice of color...

Resolve 9.0.5 OSX 10.8.2

Colorist / Aerial footage producer
http://vimeo.com/saschahaber


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Danny Duchesneau
Re: Different node, different result??
on Dec 18, 2012 at 4:37:06 pm

Ok, I found out. It has something to do with the order you place the nodes...

If I do the Lift in the first node then the Gamma in the second one I get the same result as if I was doing it in one node!! I'm also pretty sure that all the different values for let's say the Lift will concatenate on multiple nodes... Thanks for your help! Case closed!


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Juan Salvo
Re: Different node, different result??
on Dec 19, 2012 at 5:25:11 am

Just so you're aware the values do not concatenate. Each node is a unique transform. The operations are not concatenated. The order matters only in that certain operations have a result that affects the input of the following operation. And some operations do not.

Colorist | Online Editor | Post Super | VFX Artist | BD Author

http://JuanSalvo.com


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Dmitry Kitsov
Re: Different node, different result??
on Dec 19, 2012 at 11:26:31 am

Ok. My bad. But yeah. What Juan says.


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