Subject: color to greyscale

From: Rick Venable <[email-masked]>
Date: Sat, 16 Aug 1997 23:04:33 -0400 (EDT)

Someone recently asked about converting color to greyscale; I came across
the following in graphics FAQ file somewhere:

Q: How do I convert color to grayscale?
A: The NTSC formula is:

luminosity = 0.299 red + 0.587 green + 0.114 blue

NTSC is a convention for television signals (in North America), so the
above is how a b&w TV should display a color broadcast.  The resulting
luminosity will be over the same range as the red, green, and blue values,
typically 0..1 or 0..255

For an existing image file of some sort (PostScript or other format),
there's a fair number of freeware tools which can be used to convert to
greyscale; I use ghostscript, xv, and the netpbm suite a lot on Unix
systems.  A good information source for X windows freeware is

http://www.ee.ryerson.ca:8080/~elf/xapps/faq.html

--
Rick Venable                  =====\     |=|    "Eschew Obfuscation"
FDA/CBER Biophysics Lab       |____/     |=|
Bethesda, MD  U.S.A.          |   \    / |=|  ( Not an official statement or
[email-masked]  |    \  /  |=|    position of the FDA; for that,
http://nmr1.cber.nih.gov/           \/   |=|    see   http://www.fda.gov  )