[Numpy-discussion] Update for IM. a small image processing system
rays at san.rr.com
Wed Jan 7 22:35:04 CST 2004
> On Wednesday 07 January 2004 07:50, RJS wrote:
> > Most programs I have seen align a selected sub-image, then shift
> > the whole image/array (without rotation, although that would be
> If I understand you well, you essentially want to estimate a shift
> images. I have some code that can do that. I do not intend to include
> nd_image for now, but I can send you the code.
Yes, please. I sure that it's better/faster than my PIL or PythonMagick
efforts. I don't know about machine vision etc, but shift is indispensable
for video astronomy.
> > 2. A fast method(ology) to do weighted sums of 2D arrays with a mask
> > available for each array.
> I think this can be achieved relatively easily with standard numarray
Yes, it is straight-forward, in a way, but I'm always scouring the net for
C and Python algorithms. Very (most?) often they're better than my own.
This app is really a proof-of-concept; hopefully others will incorporate
the "clipped image stacking" into their already fine astro apps.
The problem is that the standard methods - median, mean, or summing - all
suffer when long images in unequal exposure stacks have large clipped regions.
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