| Re: PostScript and TrueColor images [message #73061 is a reply to message #73060] |
Fri, 22 October 2010 11:59   |
natha
Messages: 482
Registered: October 2007
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Senior Member |
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The maximum value for BITS is 8
BITS_PER_PIXEL
(PS)
IDL is capable of producing PostScript images with 1, 2, 4, or 8 bits
per pixel. Using more bits per pixel gives higher resolution at the
cost of generating larger files. BITS_PER_PIXEL is used to specify the
number of bits to use. If you do not specify a value for
BITS_PER_PIXEL, a default value of 4 is used.
It should be noted that many laser printers, including the original
Apple Laserwriter are capable of only 32 different shades of gray
(which can be represented by 5 bits). Thus, specifying 8 bits per
pixel does not give 256 apparent shades of grey as might be expected,
only 32, at a cost of sending twice the number of bits to the printer.
Often, 4 bits (16 levels of gray) will give acceptable results with a
large savings in file size.
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