Scanning a folder on a hard disk is very fast. You can expect to take about 2 seconds to scan a folder with over 100 files in it. However scanning an entire volume can be somewhat slower, as the application has to examine every file to see if it might be a GIF picture. As a guide, the author's 100 Mb hard disk took 47 seconds to scan. Scanning an entire CDROM can take correspondingly longer (CDROMs usually contain 600 Mb of data), particularly if it is a Mac CDROM with many sub-folders in it. Users are strongly advised to create "Tag files" of their CDROMs which, once initially created, are much faster to process.
As an example, the author extracted the following times using a Mac IIci processing the "GIFs Galore" CDROM from Walnut Creek, 1st edition. This CDROM has 6,483 GIF pictures on it.
Initial scan of CDROM:
Writing tag file:
Reading tag file:
As you can see, it is over 40 times as fast to read the tag file (which already has all the GIF picture names and folder codes in it), than to scan the CDROM directly.
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Page updated on Wednesday, 15 December 2004