achhabra@uceng.UC.EDU (atul k chhabra) (04/17/89)
I am posting this for a friend who does not have access to the net. Please
send e-mail replies to me and I will forward it to him.
I am in need of a subroutine in C or Fortran (mathematical expression would
be sufficient) to convert digitized NTSC signal to either YIQ or RGB signal.
The NTSC was sampled at 4 times the sub-carrier frequency and has values
from 0 to 255; alternate lines are 180 degree out of phase. Any information
or reference to book, paper concerning this would also be appreciated.
Thank you.
Tien Tran
Dept. of ECE
University of Cincinnati
Atul
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Atul K. Chhabra INTERNET: achhabra@uceng.uc.edu
811J Rhodes Hall, ML 030
Dept. of Electrical &
Computer Engineering
University of Cincinnati
Cincinnati, OH 45221-0030 Phone: (513)556-4766
---------------------------------------------------------------------------clinsley@cup.portal.com (Charles Chuck Linsley) (04/23/89)
Atul, Sorry to post this, but somebody's mailer threw up on your return path, and I got a headache reading the headers trying to find out who, and what it didn't like. > I am in need of a subroutine in C or Fortran (mathematical expression would > be sufficient) to convert digitized NTSC signal to either YIQ or RGB signal. > The NTSC was sampled at 4 times the sub-carrier frequency and has values > from 0 to 255; alternate lines are 180 degree out of phase. Any information > or reference to book, paper concerning this would also be appreciated. If you get any useful response to this, could you either e-mail a copy or summarize to the net? Thanks, Chuck clinsley@cup.portal.com ..decvax!sun!portal!clinsley CIS: 72357,2504 I don't need a disclaimer. This account has nothing to do with my job.
hutch@celerity.uucp (Jim Hutchison) (04/25/89)
In article <883@uceng.UC.EDU>: >[...] convert digitized NTSC signal to either YIQ or RGB signal. >The NTSC was sampled at 4 times the sub-carrier frequency and has values >from 0 to 255; alternate lines are 180 degree out of phase. Any information >or reference to book, paper concerning this would also be appreciated. Looking at NTSC, you get the luminance (Y) from a low frequency component of the signal and chroma (I and Q) from the frequency components. <- white /| /\ /\/\/ |/ \/\/\ -+ +-||||-' `-+ <- black +--+ +- |---- image ---| --time--> As to your getting the I and Q values back out of the samples, maybe that "new" cosine encoding the "1.2 bits per video pixel" folks are up to would get you values of theta which you could use. The function I am refering to is like a fourier transform except that it works with angular data such as I and Q. Any comments folks? /* Jim Hutchison {dcdwest,ucbvax}!ucsd!celerity!hutch */ /* Disclaimor: I am not an official spokesman for FPS computing */