  The unrivalled spatial resolution of the Chandra X-ray observatory has
allowed many breakthroughs to be made in high energy astrophysics. Here we
explore applications of Gaussian Gradient Magnitude (GGM) filtering to X-ray
data, which dramatically improves the clarity of surface brightness edges in
X-ray observations, and maps gradients in X-ray surface brightness over a range
of spatial scales. In galaxy clusters, we find that this method is able to
reveal remarkable substructure behind the cold fronts in Abell 2142 and Abell
496, possibly the result of Kelvin Helmholtz instabilities. In Abell 2319 and
Abell 3667, we demonstrate that the GGM filter can provide a straightforward
way of mapping variations in the widths and jump ratios along the lengths of
cold fronts. We present results from our ongoing programme of analysing the
Chandra and XMM-Newton archives with the GGM filter. In the Perseus cluster we
identify a previously unseen edge around 850 kpc from the core to the east,
lying outside a known large scale cold front, which is possibly a bow shock. In
MKW 3s we find an unusual 'V' shape surface brightness enhancement starting at
the cluster core, which may be linked to the AGN jet. In the Crab nebula a new,
moving feature in the outer part of the torus is identified which moves across
the plane of the sky at a speed of ~0.1c, and lies much further from the
central pulsar than the previous motions seen by Chandra.
