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Fourier transforming TIFF (2D) images

• To: mathgroup at christensen.Cybernetics.NET
• Subject: [mg414] Fourier transforming TIFF (2D) images
• From: dmwood at sst.nrel.gov (David M. Wood)
• Date: Thu, 19 Jan 95 17:29:47 MST

Dear MathGroup,

  This problem has probably arisen many times before, but here it is again:
I have a gray-scale scanned image, stored as a TIFF file [8 bits or 256 
levels per pixel], and would like to 

(1) convert the intensity value for each pixel into a floating-point value, 
say between 0. and 1., and

(2) Fourier transform the resulting (presumably two-dimensional) array.

 Has anyone gone through the trouble to look up the TIFF standard and write
a utility Notebook to transform a TIFF into such an array?

[The image turns out to be a photomicrograph of an artifically periodic
structure, and I'd like to compare its *predicted* diffraction pattern (for
visible light, as it turns out, as you'd expect from the fact the image is
a photograph) with its observed light diffraction pattern, which is
proportional to the Fourier transform of the deviation from 1 of its index of
refraction.]

Many thanks!

David M. Wood           ||      Solid State Theory Group
dmwood at nrel.nrel.gov    ||      Branch 4510 
Phone: (303) 384-6642   ||      National Renewable Energy Laboratory
Fax:   (303) 384-6531   ||      1617 Cole Blvd., Golden, CO 80401-3393
No NeXTMail here please :(