Explaining Premultiplicaiton and unpremultiplication. Breakdowns of Over and Addmix, and tricks to gamma the alpha before overing. Also at the end, talking about the importance of unpremulting before color corrections (wrong and right ways to do CCs).
This tutorial uses basic colors with a transition to teach these merging techniques and the math behind them. The math and techniques are the same for complex images and alphas, but I felt it was easier to demonstrate this way. If you are bored by the beginning sections (they can be a bit basic), I’d highly recommend skipping ahead to the “gamma-ing the alpha before an over” section. I Hope this de-mystifies some complex concept of merging images, and how to use the addmix tool.
Should be 1 more tutorial left (with a possible bonus to the despill section), presenting a template script and explaining how I have put together all of these concepts we have discussed in order to bring a full key together. This includes tips and tricks to getting around common problems in keying, despilling, and merging. I hope to have this to you guys soon.
2:01 Multiplying (how alphas are applied, premult and unpremult)
5:47 Over – Breakdown (math explained)
8:28 Overing an unpremultiplied image
10:21 Overing a double premultiplied image
13:42 Gamma-ing the Alpha before an Over
18:36 Gamma-ing the Alpha (practical example)
19:56 Addmix Breakdown
26:41 Addmix Techniques
30:25 Unpremulting before Color Corrections
Thanks for all those that are watching and learning. I am really glad I can help.
Heres a tutorial about how to despill in ways to customize the color of the despill. We move away from gray despills towards more useful colors, such as the BG or the subject. Here I go over keylight, huecorrect, talk about keeping luminance values and using the BG’s Luminance to affect the despill color. I then talk about combining despills just like combing keys, and show a little trick with the alpha’s gamma prior to merging over. More to come!
0:00 Keylight for despilling
6:00 Adding luminance back
11:45 Using BG luminance
15:51 Despill matte desaturate fix (finding max of each channel)
18:42 Hue correct for despilling
23:03 Comp example with different despills
28:46 Combining despills
31:10 Bonus: Alpha gamma before over
34:01 Comparison, final thoughts
Thanks for all your support!
0:40 what is despill?
3:40 Separating the Despill process from the Alpha process
7:33 Core Despill and Edge Despill
I’m going over the first section of Despilling. I talk about what despill is, why you need to remove it, how it should be separated from the alpha process, and combining core and edge despills.
The 2 main goals of despilling are:
1.) Removing any spill while still maintaining the original colors in the plate
2.) Blending the subjects edges with a BG colors
Here is the link to a great despill tutorial which goes over blending BG colors using the difference matte of a despilled plate –> to the original plate. If you are new to the concept of blending your despill with the background then you are really going to like this video. He talks about flame in the beginning of the video and switches to nuke later.
Thanks for watching, next I’ll go over how to achieve and control the despill to get what you need.
Sorry for not posting in a couple months, I have been traveling and working. But I am ready to finish off this series. I think you guys will like this one because I go over some techniques on the IBK workflow. The first part of the video I show you a comparison between how I usually see IBK being used and the IBK stacked technique. There are 4 examples (a greenscreen, a bluescreen, a hair problem, and a shadow problem) that I go over and explain the concept of what the IBK is doing, and the importance of the IBK Color, or cleanplate.
Next I give you a step by step breakdown of how to setup this IBK stacked techniques by building these 4 examples from scratch. If you are already familiar with IBK and want to jump into the step by step process of this stacked technique, you can just to 7:09 (Step by Step process, example 1 greenscreen).
0:45 Comparison 1 greenscreen example
3:54 Comparison 2 bluescreen example
4:31 Comparison 3 hair example
5:53 Comparison 4 shadows and markers example
7:09 Step by Step process, example 1 greenscreen
17:12 step by step example 2 bluescreen
22:15 step by step example 3 hair and assisted eroding
27:37 step by step example 4 shadows / cleanplate customization
At one point, my cursor disappears in the recording. Something must have gone wrong during the recording process, but you should still be able to see me clicking and marquee-ing stuff.
I’m glad to be moving onto the despill section, as I think it usually is overlooked. In reality it’s just as important as the alpha, if not MORE important.
0:00 Intro, RGB channels
8:37 Adding all channels
11:39 Adobe After Effects Matte technique
16:21 Channel math summary
20:02 Combining Mattes with Keymix
23:20 Isolated mask Post-Grading
In this video I break down the basics and fundamentals of what keying is and how you can make keys from individual channels. I also talk about using keymix to combine different keys, and how to isolate only certain areas of the key to adjust with a post- grade.
Here is the Channel Control tool I showed in my tutorial:
Here is the Adobe After Effects Matte Technique Gizmo:
My next video should wrap up the alpha section, stay tuned.
I’d like to take a pause from the tutorials to present my new demo reel for 2014. I felt like my previous demo reel was outdated, and that I’ve had the honor to work on some awesome projects in the last year and a half. I feel like this reel better represents my skills to date, and hopefully gives me enough credentials to merit me making all these tutorials, haha. I hope you enjoy, and thank you so much for all of you who have shown support! Let the tutorials continue.
The Luma ExponBlur tool actually had some buggy channels being added to your scripts (something leftover from the nuke 6 days I think). I cleaned these channels up so it will not add unnecessary bugs or channels.
or you guys can go straight to the source here:
This is my Feather Gizmo, I will put it on nukepedia soon:
More will come!