32 bits - it's all alpha baby!

So I am absolutely astounded at how little is actually discussed about alpha channels and such, in the post production industry. It seems to be a deep abyss of information, or vice-versa, the information keeps falling into an abyss. Being in the stock footage biz, I always get really ticked off at some of the houses that can't accept a full 32 bit depth video file. We know these files as pre-keyed, alpha-keyed, masked, whatever the heck you want to call them. They show up in the Quicktime (.mov) world as files that were created in progressive mode a la rendering using the png or animation codec portions. But the funny thing is, many forget to turn on the damn "RGB plus Alpha" when doing this. It's like who is this guy Alpha anyway? And why is no longer in Beta? Yes, that was "punny". I know.

So let's first start with this guy named "Alpha". After all he is the invisible or transparent brother of Red, Green and Blue. (Okay, Photoshop guys, this also can apply to you.) But before we go there, let's get to brass tacks about computer stuff. Stuff such as bytes. Hungry? If you remember (and this applies only to people that are younger than 50 and/or worked at a company like IBM), a byte consists of 8 bits. Hence, 8 bits equals a byte, 2 bytes equals too much food, and 4 bytes equals the full depth of an RGBA rendered file. Hence, red (8 bits), green (8 bits), blue (8 bits) and Alpha (8 bits) - darn, there is that Alpha dude again. But, really, this is called a 32 bit depth file. As in 4 x 8 = 32!

So how come 8 bits for Alpha? Well, you see, back in the day, 2 bits equaled a quarter, hence 8 bits was a buck. Confused? You should be. This has absolutely nothing to do with anything about Alpha channel. But think about it. If you only got 3/4 of a buck (a.k.a. 6 bits), you can't even get something off of the Dollar Menu at Micky D's. So perhaps that last quarter may mean something yet. In video terms it means a heck of a lot!

Back to the 8 bit thing. Eight (8) bits basically gives, in computer terms, 256 variations of something. (a.k.a. 0-255) Could it be brightness? Could it be transparency? Could it be a shade value? Perhaps it delivers a bit of all of these. But that doesn't matter for this topic right now. The key is that there are 4 of these 0-255's if you include an alpha channel. So what the heck for, this alpha thingy? It's transparent! You can't even see it! So why even worry about it? Well, you can't see the air either and yet you need it to live. Don't you? Video files can do amazing things if they are beyond the typical 24 bits (3/4's remember? or instead of 32 bits). For one, they can grow really nicely into fat plump and juicy files. Yes, they are bit bigger than your standard 24 bit depth file. But they are well worth it.

Here for example is a standard 24 bit file:



Notice how the penny covers the silver dollar? Actually it is a video layer track that gets re-sized as the clip plays. The silver dollar appears only a "bit", pardon the pun. Looks pretty useless. Or I suppose one could say this is the value of our assets now.... you know... "penny on the dollar". Okay, so shoot me. :)

Here is the same thing, but with 32 bits, and, yes, you guessed right, an Alpha channel:



This is actually the exact same clip as the one before, but with the Alpha channel fully activated. So much nicer. And notice how the dollar seems to grow. Wishful thinking I suppose.

The final message here? The government will spend a dollar to save a penny? No. But more importantly, 8 bits needs to be seen (or not seen - i.e. transparent), to show 8 bits more clearly. Get it?

All right then. Now that you see the concept, stay tuned for mere detail in future blog entries right here! I will cover this topic in great detail as it is one of the more important topics to understand if you are going to be doing some cool video work. Aside from that, having this knowledge could actually yield you several 8 bits in your wallet. Stay tuned.

The Little Understood Secrets of Television Trickery - (and how to do it cheaply) - Part 2

So when you see those "quickie" comments between segments on say, for example VH1 - this is how they do it:

It is obviously most effective to get all the lines recorded prior to editing the entire episode of a show. For example, if a show, and we'll just use the example of VH1's "Best Week Ever", needs quickie commentary during various segments flashing across the screen, it makes sense to have the various hosts or hostesses simply record the commentary in one sitting. This saves time, reduces cost and sometimes can get outright silly. Of course if you were simply a passer by and saw this process in action, you would wonder, what the heck are they doing? And just why is she sitting in front of that ugly green background? This is just another reason to make good use of chroma key technology.

One never knows 100% for sure what will be running in the background as a clip, so it's easier to work with "raw" green screen footage for this purpose as this allows any footage to be inserted after the fact.

The Little Understood Secrets of Television Trickery - (and how to do it cheaply)

Ever wonder how the weather changes so quickly on TV?

OK, so we all know that the weather guys and gals are almost never accurate when they announce the future. Imagine if they were, wouldn't they be better stock market reporters?

All kidding aside though, have you ever seen a news report say on CNN, MSNBC, FOX or any channel for that matter where a live interview occurs? Typical examples are when the news has its so called "experts" chime in on a topic. These experts reside all over the country. So how do they get them on the air and live at that? To top it off, why is the weather that they are sitting in always different than the actual weather report of their location?

Recently I was visiting a buddy of mine that just so happens to be in the business of providing live link ups for just such interviews and purposes. He is a pretty smart fellow too. I suppose that's why he named his company"Live Link Ups".

So where's the magic? And just why is the weather always nice in the background of the individual being interviewed?

Really it's no magic at all. This is all done with Chroma Key or so called "green screen", "blue screen" and even in some cases other colors. The interviewee is not actually sitting in the location depicted by the background. They are actually sitting inside a nice little temperature controlled studio. Behind them is typically nothing other than a green or blue screen (or wall). Better yet, think about your local weather person on your local news. Just how do they "jump" into those satellite pictures that they use, or the weekly temperature forecast charts that are life size? This is all done with Chroma Key technology.

Of course when broadcasting live, it does take a bit of pretty expensive equipment to accomplish this nicely. Using a green or blue screen along with the proper equipment makes it easy to "implant" any image or video as a background. This of course is the "trickery" or magic that makes things not only look nice, but can give the sense of location that the "live feed" is coming in from.

Other upsides or benefits are that one has more control of bystanders not messing up the interview. This is simply because if the background happens to be video, it was shot at a time without any other equipment than a camera. Hence, no one stops to look at a camera anymore, but they will stop and try to get in the picture if they see a camera, all kinds of other equipment and yes, an anchor person. Just watch your local news when they are out and about on location. People always want their 15 seconds in the spotlight. The national morning programs actually exploit that simple fact.

So why even bring up such a trivial topic?

Well on my last visit to Live Link Ups, my buddy decided he needed to get some new backgrounds for his future clientele. So he asked me if I could help him, and take a couple of shots for him. So off we went and got us some nice background shots of office buildings. The neat thing about this is, they are still shots, not video. Talk about an inexpensive way to make things really pop.

Think about it, with a Canon Rebel XTi (the camera used) we can shoot as many shots (good or bad) as the memory chip will hold, and select the "cherries". We could expiriment to our heart's content in a very short time. We didn't have to haul heavy cameras, use up tape (or film in some cases), and most certainly we did not become the center of attraction to passers-by. Cool. We just looked like two dummies taking pictures of buildings. Little did the passers-by realize that these simple shots would be what they will see on live TV. Even cooler.

Of course he still will need to take these images and create a CD, yup a simple CD of pics that he can load any pic off of and with his equipment drive the image as the background. Neat.

What if you wanted to do the same thing, but cheaply?

Assuming you are not going to do live broadcast on TV, but rather for the internet, you can do it quite cheaply. There are plenty of products off the shelf for very little money (less than $100.00) that will let you do the same assuming you have a webcam. Some of these kits not only include the software to run on a PC, but also include a sheet (usually plastic) of green screen and even have a lapel microphone. So why not go for it if you are going to do webcasts and such. Get the whole enchilada and expiriment. Trust me, it's alot of fun and the only limit is your imagination.

There are a few things you will need to know to be successful at it though. Keep in mind that lighting and sound are very important to get some quality productions out. You can learn all about these concepts from a variety of people for free on YouTube for example. Or if you need products from software to goods for such purposes, you will find many suppliers and vendors by doing some simple google searches.

Here are just a few:

• Chroma Key Software
• Chroma Key Supplies
• Chroma Key Tutorials
• Chroma Key Special Effects

Most of all - Have Fun!

Andreas (Vader) Hohl - Imagineerest ;)