first seg of demo pipe

test/main.py

@@ -6,8 +6,8 @@ import os.path as op
 import logging
 import sys
 S = """
-first->second->fourth
-third->fourth
+getimg->fftimg->filter->ifftimg;
+mkgauss->filter;
 """
 #T.connect('second', ['third', 'fourth'], 'fourth')
 #T.compute_hash()

test/seg_mkgauss_code.py

+""" Make a Gaussian Fourier filter
+
+The Gaussian shape is set by the fwhm parameter (full width half height). 
+The amplitude is set to unity by default. 
+"""
+
+lst_par = ["fwhm" , "nx", "ny", "a"]
+lst_tag = ["fwhm"]
+
+## Image dimension
+nx = 256
+ny = 256
+
+## Gaussian full width half height 
+fwhm = 50
+
+## make a gaussian pattern
+im   = zeros((nx,ny))
+center_x = nx/2
+center_y = ny/2
+a    = 1
+fact =  - log(2) / (0.25 * fwhm * fwhm)
+for i in range(nx):
+    for j in range(ny):
+        dist    = ((i-center_x)**2) + ((j-center_y)**2) 
+        im[i,j] = a*exp(dist*fact) 
+
+## plot it
+imshow(im)
+savefig(get_data_fn("gaussian_pattern.png"))
+
+## compute its fft
+im_fft = fft2(im)
+
+## save it to disk
+save_products(get_data_fn("fft.dat"), globals(), ["im_fft"])
+
+seg_output = [fwhm]