Understanding Premultiply, Unpremultiply and Alpha Divide ( Fusion 8 )
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- Опубликовано: 18 окт 2024
- I have done a lot of research and this premultiply, unpremultiply topic, and it seems to be very confusing to many people who are not so technical. I myself could not find a good explanation for the no-tech brain! This is my first attempt trying to change that. It is probably as simple as it can get. One might need to rewatch it, but eventually, you will get it!
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I've been using Fusion for a year+ and have read and watched a number of videos on this topic. With your 4-year-old video, it really makes a lot more sense. Thank you!
Tutorials like this are the most important, thank you!
This is a brilliant tutorial. Probably the most detailed tutorial in this area I have seen.
I come from Nuke and was searching for the Fusion-Workflow, so I found your awesome explanation about how Premultiplying works. Great job! I will share this vid to all the people, who has to know these basics.. (doesn't matter in which program, the names are just different)
Thank you heaps... I would be delighted to see you on my Fusion chat channel. If you need instant help or simply wanna chat with the Fusion gods. discord.gg/GNGUNFy . You can share that with your people as well.
I just got a clearer understanding of alpha channels for ANY graphics software that i toy around in. TYVM
Thank you for this explanation! If my understanding is correct multiplying alpha and any color channel value yields an incorrect value for color correction but dividing yields the correct value. When that is completed you then multiply the alpha back in so everything is correct. Still confused but understand it a bit better now. Nice to see a channel that clears up confusion about Fusion. 😀
Thanks great explanation, love the zoomed in circle with the grid and the color inspector
Are there or is there an additional episode of LeBucksRing to the 21 episodes on the vimeo. I don' remember seeing an episode about the confusion logo on the skull as seen in the LBR promo at the end of this video . I see the logo in the textures though.
yay after 3 years i actually understand premult and unpremult lol, thanks man
Hey Vito ... will there be a complete tutorial to buy when you finished it? Watching the whole thing in a couple of days is more my kind of learning :)
SelfBio of course! you can purchase at any time. the next episode will be the biggest. so maybe 2 more months the whole thing is out.
Great explanation. About the math of division: if the alpha is 1(white), dividing any number by 1 returns the same result. Hence the color value is unchanged. If we divide a color value by alpha value of 0, well, it's not clear what it should do, as dividing by 0 is a prohibited operation in math. But I guess it returns 0 as a convention. Then what happens to color values, how do they get restored? I inspected the color values of semi-transparent pixels, and divided them by the same pixel values. For example, you r color value is 0,02, and a semi-transparent is 0,01. Your alpha value is 0.5. So 0.01/0,5=0,02. Therefore your value is restored.
Excellent explanation about alpha multiplication, what kind of problems do we get into if we don't take that into account and why it's useful to have options to treat images as premultiplied/unpremultiplied and its related operation: divide. I don't use Fusion, but it's still relevant and applicable information, regardless of the software.
I especially liked the demonstration of the effect with the two examples, it finally clicked in my brain that alpha multiplication effectively MODIFIES the RGB values of a pixel, hence all the problems that could arise later.
So based on what I have to do, I have to tell the program if the image has to be considered pre/unmultiplied and eventually insert multiply/divide nodes as needed
Very helpful and easy to understand. Thanks dude.
That's a great explanation ! Been curious about it for sooo long ! And you made it perfectly clear ! Thanks a lot !
ho dear, ho my ! I love your tuto ! Thank you. i will jump from AE to fusion by the grace of your tutoriel
excellent stuff! Nice one Vito
Best Tutorial
Thanks Vito👍
Verrrryy nice explanation, thank you. Your simplified demonstration really made me understand the what and whys of something I had previously found very confusing. I will recommend this video if anyone asked me about this concept. When I use a loader in Fusion that has the pre-divide/post multiply option, is that doing both steps for me? How does that work in a node system.
interesting question. I also want to know! :D
Amazing! But one question: I come from Davinci and if i zoom in and Turn on PixelGrid i get "halve Pixels" like a Pixel with alot more colors than just one per square. Also: After Alpha Divide i still see some Alpha below 1 but the meter gives me a correct 1 for the pixel. What do i have change to see it pixel correct?
best tutorial on youtube
Thank you! I got it now. :)
Jisuschrist, I can say I understand the theory!
Thank you so much for sharing! it maade it easy to understand
Awesome Video Vito. Very very helpful, as all your videos are :-)
That's why we have "Pre-Divide / Post-Multiply" inside BC & CC nodes.
I will make a video showing the difference and why I do not choose the ones you and other keep mentioning ;)
Thank you for the tip ViTO!!
ROBIGEMEDIA perfectly welcome
best of the best explanation ever!
Thanks. A brilliant tutorial!!
So good!! Thanks
beautiful explanation! tks!
Nice explanation. Can I follow Le Bucks Ring using Resolve 15 with Fusion integrated?
Dimitri Bastos yes but you need to use Reactor to install the wireless3D node
Thank you so much
I NEED to understand mixing a cgi and you or me in the same video
fusion god
Not the first to comment this time ;-) but this is the kind of video i like from you, i learned something, thank !
"UYH"
That genuinely annoyed me when watching the tutorial!
Jesus Christ I get it, I am working in nuke but the concept is the same I guess, but I still don't know why there is no problem with it in AE. Thanka a lot.
Anty-ayleeasing
I DIDN'T GET IT, HAHAHAHA