Adobe ILLUSTRATOR 6.0, Online Manual, Page: 634 / 893

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File size and image compression
The storage required for bitmap images
is the product of the image size,
Resolu-
tion and bit depth . A 2-by-4-inch, 1200-
ppi, 24-bit color image, for example,
requires more than 34 MB (megabytes)
of storage, while the same image at
300-ppi requires about 2 MB.
Because bitmap images can require so
much storage, many techniques have
been developed for compressing image
data to reduce storage requirements.
Compression techniques are distin-
guished by whether they remove detail
from the image. Lossless techniques
compress image data without removing
detail; lossy techniques compress
images by removing detail.
The following techniques are commonly
used to compress bitmap image data:
• Run Length Encoding (RLE) is a loss-
less compression technique supported
by the TIFF file format and some
common Windows file formats.