High-Tech Homebrew

The past few years have seen significant advances in the tools for creating visual effects with desktop computers. Yet these tools cost at least a few hundred dollars and can quickly move into the thousands with the addition of plug-ins and ancillary tools. For the independent filmmaker interested in creating the illusions of visual effects in their work, there is no cheap way to experiment with these programs and learn the concepts of visual effects production.

Fortunately, with the combination of Adobe Photoshop, QuickTime Pro, and a number of free or low-cost editing solutions, visual effects are within reach of even the penny-pinching independent.

Below are guidelines for creating three popular types of visual effects by manipulating video files as sequences of image files. Without a dedicated compositing application, we must break video clips into separate images for each frame. The process of manipulating video as image sequences is simple but time consuming. The following tasks aren’t the ideal ways of working if you have access to a compositing application like After Effects, Combustion, or Commotion, but these are a good test to see if you are ready to tackle the complex world of visual effects production before investing a big chunk of money in specialized software.

We’ll need a variety of tools to move our video into the computer, break it into image sequences, and manipulate the images. First, there are the video-oriented programs that utilize the QuickTime architecture for exporting video, such as iMovie, Final Cut Express, Premiere, EditDV, and QuickTime Player. QuickTime Player is an especially important tool in addition to another editing tool because it will act as the intermediary between the editing program and the second type of tool, the image editing application. The most well-known image editing program is Adobe Photoshop (Mac/Win, $600), a full-featured program whose features will be of use for our tasks below. We’ll use Photoshop extensively throughout this article, but there are other options that cost less (see sidebar).

First, we’ll need to capture and export the footage from the editing program. Most QuickTime-based editing programs should be able to export a QuickTime reference movie. A reference movie is a file that can open in QuickTime-aware programs that allow it to reference footage stored in other files. This will let you to export a clip from your timeline without recompressing the video, thus preserving the image quality.

Released from the confines of the editing program, we can open the video clip inside QuickTime Player in order to convert it to an image sequence.

Open the exported movie inside QuickTime Player and select Export from the File menu (if you don’t see Export as an option, you need to upgrade to QuickTime Pro).

Inside the Export window, select Movie To Image Sequence from the Export menu and click the Options button.

Inside the Options window, select an image format that you can open in your image editing program. Some safe choices are TIFF, JPEG, or PSD. Click the OK button in the Options window and the Export window, and you’ll have a folder full of separate images that represent each frame of your video. Make sure you create a new folder for each new image sequence.

With our video turned into a series of images, it’s time to open up Photoshop. When dealing with a series of images in Photoshop, it’s imperative to remember that many tasks will have to be duplicated over and over again. Fortunately, Photoshop has a feature called Actions that makes it easy to record tasks and automatically duplicate them many times. Unfortunately, there is not nearly enough space here to explain the process of recording and using Photoshop actions, so you should consult Photoshop’s help system, manual, or a third-party book on using Photoshop for more help with using Actions such as converting colors or creating frames.

We can now move onto some potential projects for our iMovie/ QuickTime/Photoshop FX system. We’ll start with a pretty basic but useful effect, the obscuring of someone’s face with a mosaic filter like that used in documentaries and reality TV shows. Using Photoshop, it’s best to use footage where the subject to be obscured is still. If it moves around much, you will have to adjust the selection area on each frame—a time-consuming task.

Step 1: Export the shot from iMovie as a QuickTime reference clip.
Step 2: Open the clip inside QuickTime Player.

Step 3: Export the clip as an image sequence.
Step 4: Open the first frame inside Photoshop.
Step 5: Create a new action inside the Actions palette and turn on recording.
Step 5: Draw a selection around the subject you wish to obscure.
Step 6: Apply a Mosaic filter to the selection.
Step 7: Turn off Action recording.

Step 8: Open Batch from the Automate section of the File menu and select the folder with your image sequence as your source. Create a new folder to create copies for your output.
Step 9: Open the new image sequence inside QuickTime Player.
Step 10: Save the Movie as a QuickTime Movie.

Next, we’ll move onto a time-consuming but more interesting effect—rotoscope animation. Rotoscope animation is the process of drawing over live action. Photoshop’s layer system allows for drawing a picture onto a

new layer, perfect for rotoscoping. Extracting an image sequence and turning it back into a video clip is the same as above for this and the next project.

Step 1: Open an image from the image sequence in Photoshop.
Step 2: Create a new layer in the Layers palette.
Step 3: Use the drawing and painting tools to draw on your new layer over the picture.
Step 4: Use Save As to save a new copy of your image with the same sequence number in a new folder. Make sure you use a format that will compile the image into a single layer, such as a JPEG.

Finally, we’ll tackle one of the most complicated tasks in the postproduction field—compositing. Compositing is the process of combining two separate images. We’ll take a simple shot with a painting in the background and replace it with a different picture. Like the mosaic effect, this task goes more smoothly if the shot and its subjects move as little as possible.

Step 1: Open the first image from the image sequence.
Step 2: Create a new Action and start recording in the Action palette.
Step 3: Open the image you want to add to the original.

Step 4: Copy and paste the replacement image in your original image and place it in the area you want. You might have to use the Transform function to resize the picture to fit the original.
Step 5: Use any sort of effects or image controls to make the image fit in with the original.
Step 6: Save your Action and use it to batch process all the original image sequences into a new one. If your original video was shot on a
tripod and the painting wasn’t obscured during the shot, you should have a convincing composite.

As stated at the beginning of this article, these ways of working are not ideal. They take up more time and disk space than they would with a dedicated compositing program that could open video files directly, but the concepts of image compositing described above apply universally to whatever system you choose to create visual effects. If you have plenty of time but not a lot of money, these steps will get you through the basics of creating many types of special effects for your film.

About :

Greg Gilpatrick is a producer and electronic media consultant in NYC.