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Go Back and Forth Fast in Preview

If you're reading a PDF in Apple's Preview software, and you follow a bookmark or an internal link to move around within the PDF, you can quickly return to where you were by pressing the keyboard shortcut Command-[ (that's Command-Left Bracket). Or, you can choose Go > Back.

The command works iteratively, so you can go back to just the previously viewed page or if you issue the command again, to the page before that, and so on. There's also an equivalent Go > Forward (Command-]).

 

 

Published in TidBITS 60.
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TechnoBITS/06-May-91

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Compression is a hot field these days, with everyone trying to squeeze the last few bytes from a compressed file. A company called Iterated Systems might top them all though, with its compression board for PC-clones. The board can save a minute and a half of moving video images on a 1.4 MB floppy, and while that doesn't sound too impressive, multiply that up to 650 MB on a CD-ROM and you get about 10 hours of video. Iterated Systems's technique uses fractal transformations, essentially replacing bits with mathematical formulas. I'm beginning to think that everything relates to fractals...or was it marketing schemes? In any event, the hardware is required for compression, but decompression can be software only and can play video at 24 to 30 frames per second without hardware. Iterated System's best compression ratio so far is 500 to 1, but keep in mind that the fractal transformations are a lossless technology, unlike JPEG compression, which is lossy.

Related articles:
BYTE -- Feb-91, pg. 32

 

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