[SciPy-user] gaussian smoothing
Alok Singhal
as8ca@virginia....
Tue Nov 6 12:06:44 CST 2007
Hi,
On 06/11/07: 09:29, Marc Beck wrote:
>
> I am a graduate assistant at the Space Science Center at Morehead
> State University. I am currently writing a program to convert raw data
> from our 21m antenna into a *.FITS image using numpy and scipy. I need
> to convolve the pixels of my image. I have three arrays: one for the
> x- coordinate, one for the y- coordinate and one for the brightness of
> the pixel. I need to feed those three arrays into a function to
> convolve the pixels and I need to get the same three arrays out with
> the new values, or the rest of the program does not work.
Here's one way to do it:
Assuming the brightness array is a two-dimensional array with shape
(nx, ny), where nx = len(x), ny = len(y); you can do something like:
# <brightness> is the two-dimensional array of brightness values,
# <sigma_x>, <sigma_y> are the sigma values for the two gaussians
# in x and y respectively. NOTE: the sigma values are in terms of array
# indices, and not in the units of x and y values.
#
# So, if x and y are uniformly spaced:
#
# sigma_x = sigma_x / (x[1]-x[0])
# sigma_y = sigma_y / (y[1]-y[0])
#
# The output image is in the array <out> in this example
from scipy.ndimage import gaussian_filter
gaussian_filter(brightness, sigma=(sigma_x, sigma_y), output=out, mode='constant', cval=0.0)
-Alok
--
Alok Singhal * *
Graduate Student, dept. of Astronomy * * *
University of Virginia
http://www.astro.virginia.edu/~as8ca/ * *
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