Edge Enhancing Filtering a Map

This example shows how to edge enhance coronal loops in an SDO/AIA image.

from __future__ import print_function, division

import numpy as np
from scipy import ndimage
import matplotlib.pyplot as plt

import astropy.units as u
from astropy.coordinates import SkyCoord

import sunpy.map
from sunpy.data.sample import AIA_171_IMAGE

We first create the Map using the sample data and make a submap of a region with some interesting loop features.

aia = sunpy.map.Map(AIA_171_IMAGE)
bl = SkyCoord(750 * u.arcsec, -200 * u.arcsec, frame=aia.coordinate_frame)
tr = SkyCoord(1500 * u.arcsec, 550 * u.arcsec, frame=aia.coordinate_frame)
aia_smap = aia.submap(bl, tr)

Next we apply an edge enhance filter to the data in both x and y directions and combine the two images together.

sx = ndimage.sobel(aia_smap.data, axis=0, mode='constant')
sy = ndimage.sobel(aia_smap.data, axis=1, mode='constant')
edge_enhanced_im = np.hypot(sx, sy)

Finally we create a new map with the edge enhanced data and plot the result.

edge_map = sunpy.map.Map(edge_enhanced_im, aia_smap.meta)

fig = plt.figure(figsize=(12, 4))
ax = fig.add_subplot(121, projection=aia_smap)
ax = fig.add_subplot(122, projection=aia_smap)

Total running time of the script: ( 0 minutes 0.624 seconds)

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