Setting up the project

Retiming playback using the Timewarp effect

About high dynamic range (HDR) footage

After Effects CS5 also supports high dynamic range (HDR) color.

The dynamic range (ratio between dark and bright regions) in the physical world far exceeds the range of human vision and of images that are printed or displayed on a monitor. But while human eyes can adapt to very different brightness levels, most cameras and computer monitors can capture and reproduce only a limited dynamic range. Photographers, motion-picture artists, and others working with digital images must be selective about what’s important in a scene, because they’re working with a limited dynamic range.

HDR footage opens up a world of possibilities, because it can represent a very wide dynamic range through the use of 32-bit floating-point numeric values. Floatingpoint numeric representations allow the same number of bits to describe a much larger range of values than integer (fixed-point) values. HDR values can contain brightness levels, including objects as bright as a candle flame or the sun, that far exceed those in 8-bit-per-channel (bpc) or 16-bpc (non-floating-point) mode. Lower dynamic range 8-bpc and 16-bpc modes can represent RGB levels only from black to white, which represents an extremely small segment of the dynamic range in the real world.

Currently, HDR images are used mostly in motion pictures, special effects, 3D work, and some high-end photography. After Effects CS5 supports HDR images in a variety of ways. For example, you can create 32-bpc projects to work with HDR footage, and you can adjust the exposure, or the amount of light captured in an image, when working with HDR images in After Effects. For more information about support in After Effects for HDR images, see After Effects Help.

The Timewarp effect in After Effects CS5 gives you precise control over a wide range of parameters when changing the playback speed of a layer, including interpolation methods, motion blur, and source cropping to eliminate unwanted artifacts.

In this exercise, you will use the Timewarp effect to change the speed of a clip for a dramatic slow-motion playback. If you haven’t already watched the sample movie for this exercise, do so now.

Start by launching After Effects and creating a new project.

1 If After Effects isn’t open, start it. Press Ctrl+Alt+Shift (Windows) or Command+Option+Shift (Mac OS) as you start it to restore default preferences.

Click OK when asked whether you want to delete your preferences file, and click Close to close the Welcome screen. After Effects opens to display an empty, untitled project.

2 Choose File > Save As.

3 In the Save As dialog box, navigate to the AECS5_CIB/Lessons/Lesson13/ Finished_Projects folder.

4 Name the project Lesson13_Timewarp.aep, and then click Save.

Дата добавления: 2014-11-20