Thank you for another great video. Learnt a lot. I can only speak for myself, but it is neither slow, nor fast. It is the right amount of progression for a beginner like myself. :)
Yes great information video, as I'm doing despill and color correction done before copy node in B pipe source plate for live action ... it's same thing and result as you have
Yes I do that as well! Please not this is not about the dispill! It was just to show premult rules so I was using dispill as a regular grading operation. Thanks so much for watching
Love your videoes, I've been watching them! I'm FXTD and I have to render sometime, they help me a lot by knowing all these things from comp side so that I can understand what comp needs!
Great tutorial. It definitely helped with my understanding of premult/unpremult but when I use ibk color/gizmo and get my key (I assume that the keyed footage is premultiplied since there's transparency), then grade the alpha (I know you say not to) to fix the key a bit *I assume when grading the alpha you don't need to use the unpremult/premult but please correct me if i'm wrong..., then I merge over my bg I still have gray around the subject's body / but the hair looks good. Is there something I am doing wrong? Any help is much appreciated.
Hey Thank you for another great video, I'm talking about this CG premultiplied by default + without linear color space We can switch color space for CG to linear without make button premultiplied on (in read node) that rule deal just with cg or also PNG image,
Well this was just a intro to the nodes themselves, we did not do any proper colour correction between plates and we did not go over settings black and white point. I have that class on my online course but not on this stream! Can’t do everything on a short stream. Anyway thanks for watching
Oh and btw some of the footage am using has been balanced already by the grading department so I did not wanted to change it but you are correct I should have been more clear about the white and black point. Live stream are hard and some stuff gets forgotten! That’s why I do pre recorded classes so they can cover everything and be correct
Hey Hugo, after unpremulting a prevously multiplyied image with an alpha mask I would expect getting back the whole image without "cutting" it out with the alpha. I must have missed something but I don't quite understand it. I'd really appreciate if you could help me out :) Thanks!
Before pre-multiplication, e.g. the background has 0.5 value. After pre-multiplication, it will become 0.0 as it will be cut off due to multiplying with 0.0 alpha. Now, if you un-premultiply, you cannot get 0.5 back in there because that information is not recoverable. Un-premultiplication is practically division. Division by zero is not mathematically supported if you know what I mean.
Sir I am working on a lot of footages where when there is a dark background.... it is difficult to get hair detail...... Keying a hair detail is not an issue.... but as soon as we premult it and Kill the spill.... it gives very visible grey edges on the hair...... then all we can do is edge detect and color the edges... which i find a bit wierd.... there must be a proper way to get rid of grey or green edges due to premult. pls help
@@HugosDesk Sir I am getting perfect hair details... But the issue is Premult.... Against a dark background. I am working in Bollywood Industry... I am searching for a proper way to blend the luminance created by Premult with the background. Against a day or a bright background there is no issue. I usually Key the footage then apply Premult to get the RGBA then use merge node to put it over background. I want to learn about a proper way where the luminance created by Premult can actually blend with dark backgrounds without losing hair details.
@@HugosDesk Sir, Pls help me .... all the tutorials on UA-cam are taught on Bright backgrounds. I need luminance blending technique without losing hair details against a dark background.
@@HugosDesk like the one you are using for despil, most of he gizmos with python 2.7 are not working in Nuke 13, i cant find a way to convert the python 2.7 gizmos to python 3
@@HugosDesk like the one you are using for despil, most of he gizmos with python 2.7 are not working in Nuke 13, i cant find a way to convert the python 2.7 gizmos to python 3
I appreciate the lesson but I think your explanation of premultiplication is a little messy and you made a couple of small mistakes that makes it less comprehensible for beginners. For instance you say that using unpremult divides the alpha channel by the color but it's the opposite (color divided by the alpha). Also, when looking at the CG render you say that the gray areas of the alpha show that the render is already premultiplied, but that's not correct. You can't tell from looking at the alpha if the render is premultiplied or not; you need to look at the color channels (as you did in the previous example). Alpha stays untouched when multiplying/dividing. Still, thanks for the tutorials!
THIS HAS BEEN BOTHERING ME FOR YEARS!!!!
Glad I could help
Thanks for teaching in low speed my friend . Im new in this and i have learned so much. Many things that in other couse i cant .
Good stuff for my students. Thanks for your time and passion!
Thanks so much for your support
Thank you for another great video. Learnt a lot. I can only speak for myself, but it is neither slow, nor fast. It is the right amount of progression for a beginner like myself. :)
Thanks so much for your kind words of support
Thank you so much for your Tuto ! Its really clear and understandable ! And your english is very clear for my french understanding ^^
I now fully understand premulting. Thanks Hugo! :::) Just brushin-up on the basics again. Haha multiplication/ Gain- "Looks exactly the fargin same"!
Glad I could help
Always grateful and thankful 2 u sir..hi there myself Rony an VFX student from India
Yes great information video, as I'm doing despill and color correction done before copy node in B pipe source plate for live action ... it's same thing and result as you have
Yes I do that as well! Please not this is not about the dispill! It was just to show premult rules so I was using dispill as a regular grading operation. Thanks so much for watching
so great, thanks for your work, it's easy to follow and I learn a lot as a complete newbie haha
Love your videoes, I've been watching them! I'm FXTD and I have to render sometime, they help me a lot by knowing all these things from comp side so that I can understand what comp needs!
Thanks so much for watching
Thanks for sharing your knowledge! As a beginner, it's really helping me.
You are welcome
Thanks for this - nicely explained.
Thanks for watching
thanks for sharing 💓
Not boring at all!!
Thanks so much for saying that
Perfect ❤❤
Great tut
Thanks so much
Thanks sir❤️
Great tutorial. It definitely helped with my understanding of premult/unpremult but when I use ibk color/gizmo and get my key (I assume that the keyed footage is premultiplied since there's transparency), then grade the alpha (I know you say not to) to fix the key a bit *I assume when grading the alpha you don't need to use the unpremult/premult but please correct me if i'm wrong..., then I merge over my bg I still have gray around the subject's body / but the hair looks good. Is there something I am doing wrong? Any help is much appreciated.
Hey Thank you for another great video, I'm talking about this CG premultiplied by default + without linear color space
We can switch color space for CG to linear without make button premultiplied on (in read node)
that rule deal just with cg or also PNG image,
Good initiatives to make this video, good info but you might miss to set black and white point in grade before setting any grading.
Well this was just a intro to the nodes themselves, we did not do any proper colour correction between plates and we did not go over settings black and white point. I have that class on my online course but not on this stream! Can’t do everything on a short stream. Anyway thanks for watching
Oh and btw some of the footage am using has been balanced already by the grading department so I did not wanted to change it but you are correct I should have been more clear about the white and black point. Live stream are hard and some stuff gets forgotten! That’s why I do pre recorded classes so they can cover everything and be correct
@@HugosDesk yes, you are right !! keep on rocking !!
Thank you
You are welcome
Thumbs up
I PUT A BACKGROUND IMAGE AND A CAR ,THN THE CAR IS LIKE TRANSPARENT ON THE BACKGROUND,HATS I DO TO SOLVE IT,I AM BEGINER IN NUKE.CAN YOU HELP ME?
What if we keyout lady then no need to use alpha mask and premult
up !
Hi
Hey Hugo, after unpremulting a prevously multiplyied image with an alpha mask I would expect getting back the whole image without "cutting" it out with the alpha. I must have missed something but I don't quite understand it. I'd really appreciate if you could help me out :) Thanks!
Before pre-multiplication, e.g. the background has 0.5 value. After pre-multiplication, it will become 0.0 as it will be cut off due to multiplying with 0.0 alpha. Now, if you un-premultiply, you cannot get 0.5 back in there because that information is not recoverable. Un-premultiplication is practically division. Division by zero is not mathematically supported if you know what I mean.
@@laszlopapp2774 Thanks:)
Sir I am working on a lot of footages where when there is a dark background.... it is difficult to get hair detail...... Keying a hair detail is not an issue.... but as soon as we premult it and Kill the spill.... it gives very visible grey edges on the hair...... then all we can do is edge detect and color the edges... which i find a bit wierd.... there must be a proper way to get rid of grey or green edges due to premult. pls help
Am sorry you are having issues. It could be many things, have tried using luma keys? To maybe recover some of the detail back, also maybe the IBK?
@@HugosDesk Sir I am getting perfect hair details... But the issue is Premult.... Against a dark background. I am working in Bollywood Industry... I am searching for a proper way to blend the luminance created by Premult with the background.
Against a day or a bright background there is no issue.
I usually Key the footage then apply Premult to get the RGBA then use merge node to put it over background.
I want to learn about a proper way where the luminance created by Premult can actually blend with dark backgrounds without losing hair details.
@@HugosDesk Sir, Pls help me .... all the tutorials on UA-cam are taught on Bright backgrounds. I need luminance blending technique without losing hair details against a dark background.
How to use the gizmos in nuke 13?
Which ones?
@@HugosDesk like the one you are using for despil, most of he gizmos with python 2.7 are not working in Nuke 13, i cant find a way to convert the python 2.7 gizmos to python 3
@@HugosDesk like the one you are using for despil, most of he gizmos with python 2.7 are not working in Nuke 13, i cant find a way to convert the python 2.7 gizmos to python 3
@@animallabasg Sorry, am still on Nuke 12 in production
But where’s part 4? 😢
Am resuming live streams in April. The plan is to do them once a month. Keep an eye on my social media for annocments
I appreciate the lesson but I think your explanation of premultiplication is a little messy and you made a couple of small mistakes that makes it less comprehensible for beginners. For instance you say that using unpremult divides the alpha channel by the color but it's the opposite (color divided by the alpha). Also, when looking at the CG render you say that the gray areas of the alpha show that the render is already premultiplied, but that's not correct. You can't tell from looking at the alpha if the render is premultiplied or not; you need to look at the color channels (as you did in the previous example). Alpha stays untouched when multiplying/dividing. Still, thanks for the tutorials!
I watched the whole video and didn't understand a thing lol.