Apple QuickTime VR Manual do Utilizador descarregar pdf (Página 96)

The following table compares the codecs most often used for QTVR media.

Comp. Ideal Source Comp. Decomp. Comp. Comments

Method Material Speed Speed Ratio

Animation Computer-generated Fast Fast Lowest Poor compression

animation ratio.

Cinepak Video Slow Fast High Use as an alternative

to Photo JPEG.

Graphics Computer-generated Moderate Fast Low Only allows

animation compression at

100% quality.

Photo JPEG Photographic stills Moderate Slow Highest 25–40% quality gives

or video good results.

Best for QTVR media.

Video Video Fast Fast High Compression ratio

better than Cinepak.

Use as an alternative

to Photo JPEG.

Other ways to reduce file size

You can do one or more of the following before compressing a file to help reduce file size:

m Fill background areas with a solid color—Background color on a captured image may

look solid, but it contains small variations due to noise. If you use an image-processing

program to fill the background with a solid color, the variations disappear, and you will get

better compression.

m Crop images—If the areas of interest are only in the center of your images, but not on the

sides, crop the images.

m Dejitter object movies—Better compression can be achieved if objects are located in

precisely the same location in each view frame. See “Capturing Images for QTVR Objects”

in Chapter 8 for details on eliminating jitter from your objects.

96 Appendix A

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Apple QuickTime VR Manual do Utilizador Página 96