ell2948@ritcv.UUCP (Tyler Wilson) (04/09/88)
Subject: Re: Font Smoothing Algorithm
Reply-To: ell2948@ritcv.UUCP (Tyler Wilson)
Organization: Rochester Institute of Technology, Rochester, NY
Keywords: FFT, smoothing, spatial filter, serif/sans serif fonts
Some good suggestions. One more:
Instead of using an FFT, use a DFT. It is more flexible, you don't
have to mess with checkerboarding or wrapping the function. And for
the size transform you are doing the speed shouldn't slow it down
too much. You can more easily get any frequency value you like by
specifying in the program.
Some equations to make this article look technical:
F(u,v) <=> f(x,y) Fourier transform pairs
F(u,v) = 1/(N*M) * sum( sum( f(x,y) * e ^ (-i2pi(xu + yv)) ))
N = res in x, M = res in y
or
Real part of F(u,v) = 1/(NM) sum(sum( f(x,y) * cos(2pi(xu + yv)) ))
Imag part is same except cos is sin.
Good book:
"Linear Systems and Fourier Analysis"
can't remember exact title and Author. Will send if requested.
Includes all special functions, Fourier Transform stuff, etc.
or
"Digital Image Processing"
- Gonzolez & Wintz ( spelling wrong )
includes all DFT stuff, 1D and 2D.
have fun,
tyler
PS if anyone wants to write a little FFT program to do Image stuff
on the Amiga, let me know. I know the formulas, but not C. I
will respond this time. Some have left mail and sent messages,
but last quarter ( i am a student ) i misplaced all the addresses.