iMovie '08 How-To

WikiHow has a great tutorial up on how to get started with iMovie '08. It's a very basic tutorial that will get you up and running, creating a new project to use as a slideshow or video project.

High Dynamic Range, Part 2

This is a quick follow-up to my first post on High Dynamic Range. I don't feel that I used the best subject matter there- I really just took a few pictures to try it out.

I ended up having better luck at sundown- both in shooting a sunset (a great source of contrast and color) and in just shooting random landscape in that low-light setting. I found I could get some really moody results.

Surrealstic	More Saturated

Changing the way your HDR image is processed can have some dramatic effects on the results. Try to create different moods that fit your subject matter.

I have also learned a bit more about how HDR images are stored and processed in Photoshop. Here I will get into some technical details- but only because the knowledge has changed the way I save and process HDR images in Photoshop (for the better, I think!)

Everything on a computer is stored as bits- ones and zeros. You've probably heard this before, but consider for a moment what this means for storing image data. Putting aside the complexities of compression, a digital image is stored as a series of pixels. Each pixel is a single color, representing the smallest granularity represented by the image.

This is still fairly common knowledge- but, putting the two together, we reach an interesting point- how many bits do we need to store one pixel?

The answer is a little complicated, and gets into the topic of color depth, something that is very relevant when talking about HDR.

Each pixel is made up of several channels. In most cases, there will be three channels- red, green and blue. Other storage methods include 4-channel CMYK, or having an additional alpha channel to define transparency. (This is often called RGBA, for red, green blue plus alpha).

So, now the question becomes- how many bits do we need to store one channel of a pixel? The most common answer is "8". When you choose a raw color value in Photoshop or HTML, you specify a number between 0 and 255 for each channel. This is because each channel is represented as an 8-bit value (and 2 to the power of 8 is 256, giving us that many possible values to work with).

An 8 bit-per-channel image is often simply called a 24-bit or 32-bit image (depending on if there is room for CMYK or RGBA). This can be confusing, so keep in mind the difference between 8-bit color and 8 bits per channel.

In HDR, the idea is to allow for a wider range between the lightest areas and darkest areas of the image. If we end up squashing those color values down into a tiny range, we can lose some of that extra clarity and contrast.

For this reason, HDR images are often stored with more bits per channel. In the "Merge to HDR Pro" dialog, you can choose the numbers of bits per pixel you want to use.

Since learning about this option, I now render all of my HDR images in 32bpc first, saving the PSD file before rendering into a lower color depth. This lets me save a version of the HDR image that is as close to "original" as I know how to get at this point.

When you save your 32-bits-per-channel HDR image, you may notice a serious lack of options! There are not many image formats that support 32 bits per channel.

In order to save your 32bpc HDR image in another format (for instance, JPEG), you must first convert it to 16 or 8 bits per channel.

This will bring up the HDR Toning dialog, with all of the same presets and options as the 16-bit selection in the original "Merge to HDR Pro" dialog.

From here, you can select how you want to render the 32-bit channels, playing with the various effects as before.

The main difference is that now you have the original 32-bit version, and can easily revert to it and try different styles when rendering to 16-bit.

High Dynamic Range

Cameras are generally only capable of capturing a relatively limited range of "luminances" (gradations of brightness). This can often leave photographs feeling "flat" when compared to the original subject because the human eye is capable of perceiving more variance in the light and dark areas.

High Dynamic Range (HDR) is an imaging technique that aims to counteract this effect. It can be used on still subjects to infuse a greater sense of color and depth into your photos.

HDR is generally accomplished by taking multiple photographs of a single subject at different exposure levels. This works best if you use a tripod, and a camera with a good manual mode. Ideally, your camera supports exposure bracketing- a camera mode that automatically takes a few pictures at different exposure levels.

Underexposed	Original	Overexposed

For instance, my wife's Canon has an exposure bracketing mode that takes 3 shots at one time. It allows you to specify a range, and then it takes a photo at the current exposure setting, and one at the high and low ends of the selected range.

To make my HDR images, I took several "brackets", to get a wider sample set. This is only really possible if your subject isn't moving at all.

If your camera does not have exposure bracketing, you can still work with a completely still subject. Set the camera to manual mode, and then take several photos, each with a different shutter speed, while keeping the other settings the same.

The end result will be a set of photos, all essentially the same except for the shutter speed used to capture each one.

Unless your camera is super fancy and has built-in HDR functionality, that is. Some cameras can take the next step and combine those photos for you on board. My Casio, for instance, has a limited ability to combine multiple shots into a single image.

High-Speed Lighting Mode	Automatic Landscape Mode	Low-Light Mode

The Casio EX-FH100 has a few different modes that will combine images taken at high-speed using different exposure settings. One of them is meant for scenes with variable brightness- such as someone sitting in front of a well-lit window. Another mode is meant for low-light settings (without using a flash).

While neither camera mode really creates a true HDR image, I thought it was still worth mentioning. In my opinion, the camera's automatic "landscape" mode made for a prettier picture in this case, but you can be the judge. Under some circumstances, these modes work really well.

Using HDR creation software gives you complete control over how your photos are combined. Some quick Google searching will reveal a couple of good sites that list free HDR creation software. Gizmo's Freeware boasts the best collection of free HDR software, but I found this page on the Panotools wiki to be more informative. Your mileage may vary depending on the software you choose, so try a few of them out and pick whichever seems to work best for you.

The only tool I have personally used for HDR is Adobe Photoshop, so until I get the chance to try out other software this tutorial will only go over Photoshop.

Creating an HDR Image in Photoshop

Photoshop has a built-in automation feature for creating an HDR photo that is surprisingly easy to use.

Begin by opening up all of your images in Photoshop. The easiest way to do this is to select them all in Finder and drag them to the Photoshop icon.

Your images will open up. By default, in CS5, they will open in tabs- your behavior may vary depending on settings and version, but the overall process should be about the same.

To start the HDR automation tool, select "Merge to HDR (Pro") from the "Automate" menu, under "File".

Photoshop will ask you which files you want to use- select "Add Open Files" to bring in all of the files you've loaded.

You should see your images load into the HDR dialog. Select "OK" to proceed.

After some thinking, Photoshop will bring up this screen. You will see all of your photos, sorted by shutter speed, and a preview of the HDR result.

You can play around with the various presets and options until you get a look you like. The different presets can produce some drastically different results. Unfortunately, you can't save multiple files from here. You must repeat this entire process to create images using the different presets.

Surrealistic	More Saturation	Default Settings

When you're happy with the preview, hit "Ok" and wait a while. Photoshop will perform a series of automated tasks, combining, aligning and cropping your images to produce the final result. You can continue to modify the image in Photoshop, or simply save it as is.

Try to find some nice, still subject matter with good contrast- and snap away! Take as many photos as you can, this will give you the most flexibility once you get back to your computer. Good luck, and have fun!

If you are interested in learning a little more about HDR, I posted a follow-up shortly after writing this post. Continue reading to learn more about the technical aspects of HDR, and how to save your image before rendering it.

Featured Artist: blu

I don't know too much about this artist, "blu", except what I've seen on their page on Vimeo. The two videos posted there in the last year have captured my imagination- the use of stop-motion graffiti to create an animated story is so unique and amazing.

It's worth a watch even if you don't stay til the end, just to see this unique art form.

Fourth of July Light Art

In celebration of America's independence day, we like to light things on fire and blow stuff up.

What an excellent opportunity to talk about a phenomenon called "light art"- one of my favorite things to do with a camera. Light art is a fairly vague term that essentially means using a long exposure time and some sort of light source to "paint" on film, or in this case a CCD.

Fireworks, including (and especially!) the humble sparkler, are some of the easiest and best ways to make quick, but very fun and creative, light art.

If you've got a camera with a decent manual mode (I used my Casio), and you're at least somewhat familiar with the exposure settings and their related concepts, you're ready to create some nice-looking light art. (A tripod is also a really helpful tool).

With your camera in manual mode, what you'll basically want to do is:

	Set ISO as low as possible. Set aperture as wide as possible. Set a very slow shutter speed (which equals a long exposure time).

The idea is for the shutter speed to be slow enough for you to do something interesting with light while the shutter is open.

The exposure length you'll want to use depends on what you're going to be doing, but generally you'll want it as long as possible, assuming the camera will be steady.

Keep in mind that with longer exposure times, you'll start to see the surroundings, at least a little. For instance, this 30-second exposure caused the Hood Canal, and particularly some of the lit houses across it, to show up.

If this is a look you want- consider using a flash, which will illuminate the area and make it a "background" of sorts over which you will paint with light.

Just be careful not to use too long of an exposure time, particularly when combined with a flash- you may end up with a somewhat washed out end result- and you may even start to see "ghost" images of yourself!

This photo is a good example of not setting a long enough exposure time- a friend was trying to spell out my daughter's name ("Aurora"), but I didn't give her long enough to finish it.

Try out different perspectives- if you've got friends who can help, see if you can get far away from the subject. Combine this with long enough exposure for some of the environment to show up, and you can get different and interesting shots.

You can achieve some dynamic effects by moving the camera intentionally during the shot. In this picture, I moved the camera up to follow the path of the rocket. This movement caused an elongation of the end explosion, changing the overall image.

The most important thing (besides, of course, to be safe) is to simply be creative and have fun with it. Try out different light sources, after you've gotten started tonight with fireworks (for us Americans, anyway). Get inspired- there are lots of excellent examples of light art out there- some of it taken to a high art form, others going to the next level and creating an animated short film using light art. Good luck!

The Playstation 3 as a Video Editor

It's not often that we suddenly receive new tools for free, but with the recent release of PS3 firmware 3.40, many of us Playstation 3 owners got just that.

While Sony was touting the Playstation Plus network features, I was more interested in the new video editor and uploader. With this tool, you can combine and trim video clips, add titles, and even slow down or speed up time.

I was delighted to see this new menu item in my XMB after upgrade to 3.40.

The editor has a very simple, easy to use interface.

In the first step (not shown), you select video clips from your PS3's hard drive, and add them to a timeline.

The second step is the main video editor, shown here. This editor has the following options (clockwise from the top-right):

• Playback Speed: Lets you speed up or slow down (by 2x in either direction) specific segments of your video.
• Music: Lets you add one of a handful of preselected (and somewhat cheesy) soundtracks.
• Text: Add titles and other text to your video in various fonts and formats.
• A-B Erase: Trim sections of your video.

Right off the bat, two of the four of these are failures in my mind. "Music" could have been a huge feature, but for reasons that I can only imagine come down to licensing fears (Sony is also a music company, after all), you are not able to select a soundtrack from any of your personal audio tracks available on the hard drive of your PS3. We won't stop to question how it's any less legally ambiguous to be publishing any video from your hard drive, while somehow music is exempt.

The second useless option is "Text"- at least, if you plan on uploading to YouTube. Please, use YouTube's text overlay features instead- they are nearly as flexible, and (most importantly) they allow the user to turn them off. There's no reason to burn this stuff into your video- unless the PS3 offered some really cool text effects, which it does not.

Moving on to what's great- "A-B Erase" is easy to use, and functions just as it should. "Playback Speed" was the big surprise, to me. It works as well as you can expect, though the speed selection being limited to 50% and 200% is a bit disappointing.

Here is a quick test video I made that exercised all of these features. It took me only a few minutes to throw together. I use MediaLink, which was $20 paid software. It works flawlessly as a solution for playing iTunes music and video over the PS3- and, fortunately, also works for showing photos and video from iPhoto as well.

With MediaLink, I was able to browse my iPhoto library on my PS3, choose a clip, copy it to the PS3's hard drive, and then launch the video editor and import it right in. It was amazingly easy.

I'm not sure what Sony's intention is with this tool, exactly. To my knowledge, there are only a handful of games that support video capture- and I think you just upload to YouTube straight from the game, generally. If they were to announce global video capture ability built-in to the PS3, that would really be something- and would put this tool in context.

But, for now, it's something of a curiosity- which can be a pretty fun toy for us video enthusiasts to play with.

An Introduction to Exposure

If you have a camera that allows you to manually adjust exposure settings (and even if you don't), it pays to really understand things like aperture and ISO, and how they will affect the end result of your photograph.

The photo blog at tutsplus has a really excellent beginner's introduction to exposure. There, they go over in depth the "triangle of exposure" - an excellent model for visualizing the relationship between ISO, aperture and shutter speed. The article describes each component in detail, and then goes on to describe how they will affect things like depth of field and low-light shooting.

The author recommends a DSLR, but any camera with a manual mode will do. Both my Casio point-and-shoot and my wife's Canon have a very useable manual mode, and neither is a DSLR. The big advantages you'll get using a DSLR are much wider aperture and ISO ranges, which give you greater flexibility in composing your shot. Clearly, having better gear is always a win- but don't pass on this article just because you don't have a tremendously expensive camera.

In short, this is great information for all shutterbugs, pros and beginners alike- check it out!

Time Lapse, First Attempt

This was my first attempt at creating a time lapse video, using the beautiful Hood Canal on a very foggy day. I made a lot of mistakes, and learned quite a bit- and though there is a tremendous amount of room for improvement, all things considered I'm fairly happy with the final product.

I'm going to document my entire process as a set of tutorials, because I believe there is value in everything I did, even if was not really the best way to do it. That's how I look at it, anyway- it was all a very educational experience. However, keep in mind that if you take note of what went right and wrong in what I did, you likely will not have to use all of these steps in your own time lapse video.

Postmortem

What went right

• Choice of tripod and camera seemed to work well.
• Indoor approach worked well during the day.
• The weather worked out well.
• Good subject matter.

What went wrong

• Wrong camera mode.
• Moved camera several times during process.
• Indoor approach caused reflections at night.

Ultimately, my biggest mistake was not understanding my tools. Unfortunately, my little point-and-shoot Casio does not have an intervalometer feature, so I had to use my wife's beefier Canon, with which I am not as familiar.

Because of this, I didn't set up the camera properly. I chose a camera mode that automatically adjusts the shutter speed and aperture values on each shot, and I did not put the camera in manual focus mode, either. This caused a lot of issues with some frames being blurry, and others having different depth of field. The end result is a lot of jitteriness that is very difficult to account for in post.

Another mistake I made was one of practicality. It's very rainy where I live, so to take a time lapse like this I decided to keep the camera indoors, pointed through a very clean window. This worked fine during the day, but as night approaches you can see lights flicker on and off in the reflection of the window.

Finally, since I was really just testing this out, I moved the camera around several times during the process. At one point, I actually took it off of its tripod to go download the photos, making a short test video. This, naturally, caused some issues that were fun to try to fix in post.

Next Time

• Shoot through an open window.
• Do not interrupt the process.
• Put camera in full manual mode.
• Manually set camera focus.
• Possibly adjust shutter speed as night approaches?

Set Up

Preparing for a time-lapse is fairly straightforward:

• Choose a camera. You'll need an intervalometer (built-in or otherwise), as well as full manual mode and manual focus.
• Use a tripod, or some other flat surface. Make sure the camera will move as little as possible. 

Once you've got your gear ready, it's time to frame your shot:

• Find some dynamic subject matter that won't move much.
• Configure the right aperture, exposure, white balance, and ISO settings. 
• Make sure nothing on the camera is set to automatic.
• Put the camera in manual focus mode, bring subject into focus.
• Take a few test shots.
• Configure your intervalometer.

Your subject matter will determine how long your time lapse is going to take. I chose a skyline with clouds for my first attempt, because this is something I can tackle in a single day and get some interesting results. Clearly, if you're going to do something like capture a flower growing, the time span is going to be different. I suggest, for your first attempt, pick something you can do in a day.

Once you know what you want, set up your intervalometer. Mine, unfortunately, is only able to take 100 photos max at a time, at a minimum of 1-minute increments and a maximum of 60 minutes. Ideally, you would have more control over your settings- a timer up to 24-hours and unlimited number of shots (memory permitting) would be great.

If your test shots look good, start the process and... wait.

Post Production

The steps you'll take in post production depend on the results you get. Depending on how well your shoot went, you may or may not need to do some of the following:

• Stabilize the footage.
• Combine / align multiple takes.
• Adjust color balance or other levels.
• Slow down or speed up the timing.

In the simplest case, you stitch your photos together, output a movie and that's that. Pick and choose from the following steps to do what's right for your results.

Create Image Sequence

The first thing you'll want to do is make a movie from a set of photos. This is the only step that is absolutely necessary when making a time lapse.

I'm going to go over two separate methods, involving different software. Both of which, unfortunately, cost money- though Quicktime Pro is relatively cheap. After Effects, not so much. If you happen to have both, it's worth doing the QT method first as a quick preview.

Create an Image Sequence in Quicktime Pro

Quicktime Pro can easily import a series of images into a movie. Use the "Open Image Sequence" option under the "File" menu to open a series of images.

Select only the first image in your sequence. Make sure all of your images are in a single folder, and that they are numbered sequentially.

A dialog will pop up asking you to choose a frame rate. Choose a good balance between video length and smoothness. Between 10 and 30 FPS is usually good.

With the frames imported, you can try to preview- but you'll notice the video is very large, and depending on your system performance it may not play smoothly.

To see the video properly, you'll want to export it. Select "Export" from the "File" menu.

Select "Movie to Quicktime Movie" as the "Export" type. Don't fret too much about this, recall that Quicktime is just a container format.

Click the "Options" button to bring up the options dialog.

The "Settings" menu contains framerate and compression type options.

The "Filter" menu contains various effects, including a color balancing filter that might be handy if your pictures are not all uniform.

For now, click the "Size" button. Since your video is based on photographs, and not video frames, chances are the video is much larger than you would like.

Choose your own dimensions, or select one of the presets. You should have no problem generating 1080p output, if that's what you want.

Chances are also good that your photos are not the right aspect ratio. Check the box to preserve the ratio, and select letterbox or crop.

I prefer a crop, but if you've got something important near the edges of your subject, you might want to letterbox. There is another option "fit within dimensions"- from what I understand, this will change the output resolution so that your movie will fit properly. Not really what we want in this case, unless you're okay with a non-standard aspect ratio in our output video.

Finally, click "Ok" on any settings dialogs, and click "Save" to export your movie.

Create an Image Sequence in After Effects

Start a new composition. You'll be using this composition as your output, so set up the resolution and frame rate to be how you'd like the end movie. I chose to use the 1080p preset, but it's really up to you. Just be sure to use "square pixels".

To create an image sequence, drag a folder full of photos onto the project panel. Do not use the "Import Multiple Items" command, as this will import each photo as a separate image instead of creating a sequence.

I separated my photos into a few sets based on gaps in the time lapse where the camera had moved. If you have more than one set of photos, import one folder at a time.

You can rename footage to something more descriptive by right-cliking on a sequence and selecting "Rename". I named my footage "Take 1" through "Take 5".

Create a new composition to hold the image sequences.

This composition is going to hold the photos and provide a sort of "window" for the output. I defined the dimensions of my Images composition to be larger than each photo's size, to give me room to align and compose the different takes.

Double-click "Images" in the Project panel to open the new composition. Highlight all of your image sequences, and drag them into the timeline to add them to the composition.

You could also drag them into the viewport, letting you position them at the same time.

After Effects will line up all of the clips at the zero time marker. This might make sense in some cases, but I want the clips to follow each other sequentially.

You may need to zoom in to make sure there is no overlap or any empty frames. Once aligned, your clips should have a "stair step" look.

Now, you'll want to figure out how long your total video is. The easiest way to do this is to simply srub to the end of the video, and then look at the time marker.

Select the "Output" compostion and open up the properties window.

Set the length of the composition to the total length of all of your clips.

At this point, you can go ahead and render your composition.

Align Footage

If you've got multiple takes, each one possibly with different framing or even zoom, you're going to want to line them up so that there isn't as much of a jarring transition between them. You could simply import all of your images in a single set, and use motion stabilization, a topic we'll cover in the next section.

However, if you only have a few takes it may be simpler to line them up by hand.

Grab a corner of the blue frame around your selected layer to resize it. Be sure to hold shift while you drag- this will maintain the aspect ratio of the clip. Click and drag inside of the blue frame to move the selected layer. Select the next layer, and so on.

Drag the timeline slider back and forth across the transitions between your layers. This will help you visualize the difference between the two and line them up properly.

You can switch the view to wireframe to get a good view of how your layers line up to one another.

Stabilize Motion

After Effects has some powerful motion stabilization tools based on a flexible tracker interface. The system is actually pretty easy to use, and can produce great results, if used well. If used poorly, however, it can actually add a lot of jitter and jumps to your footage- something you may have to tweak by hand after the autmoated process is finished.

To use motion stabilization, right-click on a layer in the timeline and select the "Stabilize Motion" menu item.

This will add a new tracker to your layer, and activate the "Tracker" panel. A tracker is a complex object consisting of a few pieces- each of which can be difficult to grasp (pun intended! They're hard to grab...)

Adobe does an excellent job illustrating a tracker, so I'm going to steal the diagram straight off of their reference page for motion tracking. (I hope they don't mind!)

A.Search region
B.Feature region
C.Attach point

The search region is the outermost box of the tracker. This defines the area that After Effects will search each frame for the feature you are tracking. You'll want to click and drag on this box to expand it a bit, large enough to cover however far your footage might jump in a single frame. Keep in mind that making the search region large will greatly increase the processing time required to analyze your footage!

Click and drag inside of the tracker to move it. While moving, the tracker will show you a magnified view of the search region.

Try to pick a high-contrast area, and (most importantly) an object or feature that will be in frame as long as possible, preferably the entire clip. (Otherwise, you will need to stop and re-start the analyization in the middle, after re-framing the tracker).

The feature region defines the area that After Effects will be looking for in each frame of your footage. It's the object or feature that you want to track. Click and drag this inner box until it covers a high-contrast area, preferably an entire object or feature.

Once you're happy with your tracker, click the "Analyze Forward" button. That's the small "play"-like triangle button over on the "Tracker" panel. Depending on the size of your tracker, this may take some time- you should be able to watch its progress.

After analyzation, your tracker might look something like this (if you've got some jumpy footage). Each little blue square represents a position the tracker moved to during analyzation.

You can scrub through the timeline and see the various keyframes for each tracker point. Double check to make sure it looks right, and delete any spurious key frames, if necessary.

Note that, by default, tracking will only occur for position. This means After Effects will only shift your image horizontally or vertically- it will not scale or rotate your image. If your camera moved forward or backward during filming, or your zoom level changed, or your camera tilted (perhaps slightly, as when on a tripod in the wind) you may need to select "Scale" or "Rotation".

Selecting "Scale" or "Rotation" will cause an additional tracker to appear. Try to set it up as far from the first tracker as possible, while still following all of the same basic rules. After Effects needs this second tracker to analyze scale or rotation since these translations are relative to a secondary point.

You will also see this additional tracker in the timeline. Keep this in mind if you start deleting keyframes.

Once you're ready, click the "Apply" button in the "Tracker" panel.

"X and Y" is usually a fine option, so just click "OK".

You should now be able to render the composition and see your footage, well aligned and stabilized- hopefully looking much better!

Slowing it Down

Generally speaking, with the right equipent and proper planning, there should be no need to slow good time lapse footage down any further. If you can, just do the math in advance. Start by ansering these three questions:

• How many frames per second are you going to want? (aim for 30)
• How long do you want the end movie to be?
• How long is your event (e.g. 24 hours, 30 minute sunset, 3-week plant wilting)

Use this equation to configure the delay on your intervalometer:

Delay in seconds =	"length of event in seconds" /
	("length of movie in seconds" x "frames per second")

So, for instance, if I am recording 8 hours worth of clouds, and I want a video that is 30 frames per second and 15 seconds long, that would give me:

Delay in seconds =	(8 hours x 60 minutes / hour x 60 seconds / minute) /
	(15 seconds x 30 frames per second)

Photos / second = 28800 seconds / 450 frames
Photos / second = 64

If your camera and intervalomter can handle delays in seconds, then good for you! If not, round this down to the nearest minute. The built-in intervalomter on my wife's Canon has a delay specified in minutes- so one minute is as fast as it can go. I imagine this is probably the case for many intervalometers.

So, as you can see here, 15 seconds is about all the footage I will get from this camera at 30 frames per second from an an 8-hour span. That's quite a time compression! If you're not happy with that, there are a few things you can do in post production to stretch out your footage.

Change the Frame Rate

Quicktime Pro, After Effects, and just about any other video editing software should let you change the frame rate of a video file, or re-export it video with a new frame rate. For instance, lowering the frame rate to 15FPS (or, rendering it at that frame rate in the first place!) will double the length of a 30FPS video.

Once you get much below 10FPS, your eye will probably start to pick up on it, and it will look "jittery". This is because your eye is finding it easier to pick out individual frames, and the transition between each one becomes less blurred and fluid. Eventually, it will literally start looking like a slideshow. Which might be pretty, but that's another tutorial alltogether.

Using Time Warp in After Effects

After Effects has an effect called "Time Warp" that can speed up or slow down a clip. The cool thing about this effect is that it will create interpolated frames for you. What does that mean, you ask?

It means that, if you use "Time Warp" with the "Speed" variable set to "50%" (the default), your clip will get twice as long (and twice as slow). But- and here's the magic part- the framerate will stay the same (say, 30FPS).

After Effects does this by inserting a new frame in between each frame of your video footage. It creates this frame by intelligently (more or less) combining the surrounding frames.

Here is an example of time warp in action, using some video of my daughter. I slowed this video down by 50%, and then compared two frames with the new frame that was created in between them. Note that, in the new video, every other frame is an interpolated frame.

Frame
Original Time	46;26	N/A	46;27
Interpolated Time	1:33;22	1:33;23	1:33;24

You can see that After Effects does a pretty good job (in most cases) of blending the two frames. Sometimes things get a little blurry or watery looking, but you don't notice this so much when the video is in motion. I have had limited success going much slower than 50%, however- once your interpolated frames start outnumbering the real onces, the effects gets really noticeable. I'll cover this more in-depth in a later post specifically about time warping.

Let's walk through the math used to get the times listed above, and how to compare frames before and after time warping. For instance, if you want to find the frame that was previously at "46;27" in your new timewarped video, you have to apply the inverse of your time scaling factor. Or, another way to look at it, divide by the time scaling factor.

In this case, my time scale is 50% - meaning I need to divide by 50%, or multiply by 2.

Fortunately, After Effects will do the hardest part of this math for you. Simply multiply both numbers by 2, and plug those values into After Effects: "46;27" x 2 = "92;54", which After Effects correctly translates into "1:33;24".

Now, if you're smart, you'll catch something I can't quite explain- to grab the interpolated frame, I actually had to go to 1:33;25 - two frames later than I thought. I'll report back here when I figure out why that is.

To add the time warp effect to your footage, right-click and find it under "Effect", then "Time".

The "Effect Controls" panel will appear. Here you can control the current effect, in this case "Time Warp". The two most important controls here are "Method" and "Speed". "Speed" is the percentage at which the effected video will play- so "50%" means it will play at half speed.

The values for "Method" are as follows:

• Pixel Motion Creates a new frame by analyzing the pixel movement in nearby frames and creating motion vectors.
• Frame Mix Creates a new frame by blending existing frames.
• Whole Frames Duplicates the last frame shown.

That's the offical word, anyway. My take on it is this:

• Pixel MotionThis can create the biggest "wow" effect, if it works well. If it works poorly, it creates weird watery effects that can be very noticeable.
• Frame MixThis method can work very well with motion blur, as long as you don't mind the motion looking really blurry.
• Whole FramesThis is basically the cheap method- it's barely a step up from just lowering the frame rate.

As always, experiment with each option and see what looks best for you and your particular situation.

Effects will also appear in the timeline. Anything with a "stopwatch" icon, such as "Speed", can be keyframed.

This button, in the timeline controls, will toggle automatic keyframe creation. With this on, any change you make (such as moving a layer, or changing "Speed" in the "Time Warp" effects) will be stored in a keyframe. When the video is rendered, keyframed values transition smoothly from one keyframe value to the next.

By keyframing the "Speed" variable you can create some dramatic effects with time- this will be a topic for a later post.

Once you have your time warp effect configured, you may need to adjust the length of your clip. In particular, if you've slowed down footage- your clip is now longer, and you may need to account for that.

Right-click on your clip in the timeline, and select "Enable Time Remapping", in the "Time" menu. This will allow you to "resize" your clip in the timeline.

Click on the right end of your clip in the timeline, and drag it to the right to resize it. If you've slowed your clip down 50%, you'll need to make it twice as long if you want all of the footage to appear in the timeline.

Do not modify the "Time Remap" keyframes. That is an alternate way to re-scale time, but it doesn't provide as much control as the time warp effect.

You will now need to find the new end time of your movie, and set your Output composition length accordingly. For a straight 50% time warp, it's as simple as doubling the original length- but it gets much more complex when you start keyframing the speed.

You can now render the composition to see your slowed-down footage. Keep an eye out for any strange-looking artifacts!

Adding Pan and Zoom

If you have a camera with more than a few megapixels worth of resolution (and you should!) you may notice that, even when outputting in 1080p, you've got a lot of extra frame to play with. You can simply downscale it, of course- or, if you don't mind getting a little cheesy, you can have some fun with those extra pixels.

Select your Output layer, and expand its timeline. You may or may not see one more or more motion trackers in there- but below that, you will see a "Transform" section.

Turning on the "Auto Keyframe" feature makes animation in After Effects easy. This means that any changes you make to your layers are recorded in a keyframe at the selected time.

Scrub through your timeline to find an interesting point, then resize and move your frame.

You'll notice keyframes are created each time you do this. When you play the video, After Effects will smoothly zoom and pan between your keyframes.

Keep an eye out for times when one of your sequences goes out of frame- you'll see black bars appear on the side of your screen. Adjust your keyframes to keep your frame filled at all times.

At this point, I've covered everything I did to my first time lapse, for better or worse! If you haven't rendered your experiment already, do it now and see what you've got!

Render Sequence in After Effects

When you are finished with your After Effects project, or if you just want to check your progress, you'll want to render your output composition.

With your Output composition selected, use the "Make Movie" menu item, under "Composition".

This will add a new item to your render queue. Press the "Render" button to begin rendering to a file.

You can expand items in the render queue to change output settings. In particular, you may want to compress the output (H.264 is always a good choice). For me, I know that I am taking this footage and putting it in iMovie. To avoid double compression, I'm going to leave the output uncompressed. Note that uncompressed video is quite large, so this may not be an appropriate choice. Once I've learned to use After Effects more extensively, I will no longer use iMovie and instead output compressed video straight from After Effects.

By default, the file will have the composition name ("Output" in our case) and be saved to your desktop. Go find the file, and enjoy your results!