Posted by Jason on August 16th, 2010
Have you ever had a hard time getting an apostrophe while typing on your iPad? Because I have.
Initially I did it the long way by hitting the “.?123″ button. Eventually I realized I could just press and hold the comma / exclamation point button for a slightly faster selection. It still took some time though, and the few seconds it took to bring up the apostrophe was enough to break the flow of typing. But then I discovered a shortcut where an apostrophe appears if you tap the comma / exclamation button and slide your finger up a little before releasing. Tada. Instant apostrophe.
Posted by Jason on June 9th, 2010
What is color subsampling?
Our eyes don’t see all of the subtle variations between every color. We do, however, see the difference in shades of a color. In video, this is called luminance. The color is referred to as chroma, or chrominance. Since the dawn of video, cameras have been using a technique to reduce the amount of color information captured to reduce the amount of bandwidth needed to deliver it. Since our eyes won’t see these colors anyway, we’re not missing much.
How is it done?
The most common model of color subsampling uses an area that’s 4 by 1. Four pixels wide and one pixel high. For each of those pixels measurements are taken, and values assigned. The first is for how luminous each is, measuring once for each pixel. When we’re done we’ll have four unique measurements for each of our four pixels.
Next, color information is measured. We already know that our eyes aren’t going to see all of the color that we’ trying to record, so instead of getting a color value for each pixel we’ll be averaging the colors together. This dramatically reduces the amount of data needed to transport the image. Colors accuracy is also significantly reduced. When we’re done we’ll have one measurement that represents four pixels.
This example assumes we’re using 4:1:1 sampling. It’s commonly found in consumer DV cameras and for most applications it’s just fine. The real problem starts when you get into color correction and — even more so — when working with green screen. It’s then that the more color information you have to work with the better off you’re going to be.
Below are brief descriptions for some of the most popular color sampling methods.
4:1:1
DV video, represents a highly subsampled image. Sample area is four pixels wide and one pixel high. Found in cameras like the DVX-100.
4:2:0
Some HD cameras use this including the Sony EX-1 and EX-3. Technically, its the same as 4:1:1. The camera is still averaging the color of four pixels down to one. The difference is that the sample size is two pixels high by two pixels wide. Commonly used in HDV cameras.
4:2:2
Vastly superior to 4:2:0 and 4:1:1. Each color sample size is further broken down from four pixels to two, yielding much higher color accuracy. Used by DVCPRO HD and Digital Betacam.
4:4:4
Every color is represented as accurately as possible. No subsampling. Used by RED, Viper and Genesis camera systems.
4:4:4:4
Same as 4:4:4, but includes an alpha channel, typically used for chroma keying.
Why care?
Maybe you’ve noticed artifacts in your image; blockiness where colors bump up against each other. This is because the same algorithms are trying to average the colors the best it can. Sometimes, especially in these transitional places, it may guess wrong.
This is important to understand when doing color correction, and absolutely essential when doing any kind of chroma keying. If you’re working with a camera that has low color sampling resolution you’ll need to know what kind of limitations you’re up against. You may not actually be able to get the seamless VFX shot you originally had planned. But that’s filmmaking, right?
Now what?
I encourage you to figure out what color sampling method your camera uses. The more you know about your camera, the more you’re going to be able to get out of it. You’re also going to make things easier on yourself once you get to editing.
Additional resources
Color Subsampling on DVXuser
Subsampling notation PDF
Posted by Jason on August 10th, 2009
Say you’ve spent all day editing a video and now you’re excited to show it off. You don’t know too much about color correction but maybe noticed that your video looks a little red. And the colors are a little flat. And there’s not a lot of definition in the shadows.
Content might be king, but the big guy doesn’t wear a crown because it’s comfortable.
A Clarification
Color correction is the process of removing color casts due to a white imbalance, adjusting for poorly exposed shots, and improving contrast. Color grading is the process of manipulating color in your footage to produce a desired look.
That should answer the why. But what are you correcting? Simply, you’re looking to normalize your footage. Or maybe it’s better to call it naturalizing. Your goal is to make your video look normal. Properly exposed. Not-tinted. Uniform.
For reference, I run everything I shoot through Color for adjustments. From iPhone videos to the big-time client projects, I don’t consider it finished until it’s gone through (at least) a contrast & white balance grade. In fact, I specifically shoot in a way that gives me the greatest flexibility for correcting and grading. It’s similar to shooting RAW on your DSLR. But that’s for another day.
So here we are. Basic color correction. You can do everything here with Final Cut’s “Color Corrector 3-way” filter (discussed below), but if you have Final Cut Studio, you might as well use Color — you’ll have far more control over your adjustments.
Contrast
I always start by adjusting contrast.
Unless you’re shooting with your shadows absolutely black (which you shouldn’t — you want flexibility) you should start by pulling the darkest areas down toward the black. Not so much that you’re losing a ton of color information, but enough to create a distinction between dark and semi-dark.
On the other end, your highlights shouldn’t be blown out. By which I mean not peaking above 100%. Anything above 100% is considered super white and not broadcast safe. Here’s a quick before and after look at the RGB histogram for the clip above.
Before Adjustments
The most important thing to note here is how the highlights are squished along the top (the thick yellow line near the top separates white from super white). The shadows are spread along the lower half.
After Adjustments
With the highlights reigned in, the graph isn’t top or bottom heavy. Most of the color is in the middle and we’ve got a few shadows near the bottom.
How you shoot has a lot to do with how much flexibility you’ll have while grading. For example, many cameras include a handy zebra striping feature (see below) to let you know when you’re approaching your white limit. No striping means you’re within the limit.
Final Cut’s Color Corrector 3-way Filter
If you’re using Final Cut Express or if Color’s interface scares you, you might be familiar with this guy.
From left to right you see three color wheels and sliders to play with. The far left is for adjusting shadows. The center is for mid-tones. The far right is for highlights. Use the sliders below the color wheels to adjust contrast, and the wheels themselves for color adjustments. Take it slow — minor adjustments can produce dramatic results.
Your goal is to maintain consistency across your clips.
White Balance Adjustment
You’ll want to look at your clips for any red or blue casting. Casting comes from maladjusted white balance and can cause ugliness between shots. This is the red tinting I mentioned in the opening paragraph. Pretty much every camera you encounter these days has some kind of automatic white balance, so most of the time it’ll be spot-on. When it’s not you need to fix it by adding the opposite of whatever color you have too much of. Here’s a handy color wheel for reference.
If you’re using the Color Corrector 3-way filter in Final Cut Express or Final Cut Pro you’ll want to use the center wheel to remove most of whatever color cast your clips might have.
Again, your goal is to be as consistent as possible. When you’re done making your adjustments every clip in your sequence should be consistent from shot to shot. If you notice one clip that looks a little blue, everybody else is going to notice it too. Same goes for shadows. If it’s too light or too dark, you’ll know, and so will we.
Coloring
When you have your footage looking good (and unified) you can choose to add a little bit of style. Maybe your video is set in the summer so you want to give it a warm feel. You’ll tint it orange. Or say your characters are locked in a cold freezer, you add blue. Maybe you want to show off an afternoon by the waterfront so you punch up the colors a little bit.
This is the fun part of color grading. You’re free to create a look all your own at this point — adjusting saturation, vignetting, removing colors altogether, etc. And because you’ve already corrected your clips for color & contrast, any look you create will be applied uniformly. Experiment and take time to create a look that makes you happy.
Posted by Jason on August 30th, 2008
Update: Commenter Cameron points to this Apple Kbase article that should resolve this problem. So hooray for that. And for Cameron.
I have more problems with Soundtrack Pro than any other application on my Mac. Between crashing, and the seemingly endless file save progress indicators, I have managed to tip-toe my way through several successful projects. But it’s the looming uncertainty that puts fear in me whenever I send a project from Final Cut to Soundtrack Pro.
Recently I had the unique pleasure of being treated an an error I haven’t seen before, the curiously named CNSExceptionWrapper. I say it’s curious because most methods in the OS X frameworks start with NS, a remnant of NeXTSTEP — of which OS X is a direct descendent. The C prefix is a little peculiar however, and I wonder if it has something to do with one of the Core Services. Perhaps Core Audio? Who knows. I was only able to find a few references to the error after searching, and still haven’t found an explanation for what caused it.
Last night I ran into an issue I’ve had off and on for quite a while. Let’s say I’ve recorded a project using two different audio sources; a shotgun on the left channel and a lav on the right channel. I bring them into Soundtrack Pro and mute the left channel (I usually just use it for backup), and proceed to do my work on the right channel. When it’s ready I export the master mix back to Final Cut Pro and… WHAT?! None of my changes/edits made it through! In fact the sound I hear couldn’t have possibly come from a lavaliere microphone. So, completely confused and demoralized, I switch back to Soundtrack Pro and play the sequence. The audio now sounds the same as it did in Final Cut, but completely different than it sounded just a minute ago in Soundtrack Pro.
What’s going on?
For whatever reason, it appears that Soundtrack Pro sometimes decides that the channel you think you’re working with isn’t the one it thinks you should be working with. So it changes it for you at export. How helpful.
To correct this (and trust me, this is a huge pain) right-click on the clip in the timeline. Choose Channel Select > Mono > 1 (or whichever channel isn’t currently checked). You’re picking the channel you DON’T want. Then right-click again and choose Channel Select > Mono > 2 (bringing it back to the channel you do want).
Repeat for every single clip in your sequence.
When I discovered this solution (and I’m using that term loosely) I was working on a project that’s only 60 seconds long. You can see how this could be a major issue for projects that are something like 60 minutes or longer. Even manually changing the tracks for every clip in a five minute sequence would be a chore. It’s something I really hope to see fixed in a software update in the future. It’s hard for me to believe that I’m the only person that’s experienced this issue.
Posted by Jason on August 29th, 2008
I haven’t posted anything in a while. You may have noticed. To make myself feel better about my own blogging failure I thought I’d pass along a tip that the people at Creative Cow recently wrote about; key bindings.
It’s a $10 name for describing how to create your own keyboard shortcuts within Final Cut Pro. This can be a huge time saver. For example, to get started in Soundtrack Pro I normally have to right click (or control-click) on a sequence in the Browser, select Send To, then choose Soundtrack Pro Multitrack Project. Alternatively, one could bind the action to their very own fancy-shmancy keyboard shortcut and accomplish the same task in a fraction of a second. On my system, I have this action set to Option-Shift-S.
The process of actually editing these shortcuts is as simple as you might expect something in FCP to be (meh). Start by hitting Option-H to open the keyboard layout editor, then click on the little lock icon in the lower left to allow changes. From there you can have at it by choosing the key combination tabs along the top of the window, and searching for the desired command in the search area. Simply drag the command onto the key you want to bind it to.
Creative Cow lists a bunch of great shortcuts in their post, but I’d also suggest setting Render All to the letter Y. It’s a letter that’s not used by default for anything, and it’s something you’re probably going to be doing a lot of. Consider also binding Send to Color and Send to Motion to Option-Shift-C and Option-Shift-M, receptively.
The last thing you’re going to want to do is to save your layout (and if you really want to blow your own mind, you can even set a keyboard shortcut for that too!). From the menu bar choose Tools > Keyboard Layout > Save Keyboard Layout… and give it a name. Something like, “Jason’s Keyboard,” or, “Master of space and time” would do nicely.
And finally, if things get too crazy in there, you can always hit the reset button to get yourself back to the Apple-supplied shortcuts.