On Wednesday 07 January 2004 07:50, RJS wrote:
I have uploaded a new version of my small image processing system IM to "http://members.tripod.com/~edcjones/IM-01.01.04.tar.gz". Most of the code in IM (pronounced "I'm") is inferior to "nd_image" so I will eventually convert it all to "nd_image".
...
nd_image is however also still being developed and I am looking for
directions to
further work on. I wondered if there is anything you would like to see
in there?
I have been working with Pythonmagic and numarray for a particular astronomy project/technique, and IM has a few things I might use; nd_image also has some interesting functions as well.
I want to align and specially stack 8-bit grayscale images from a FITS cube, or BMP set, currently. So, my suggestions (hint, hint) are: 1. A method to shift an array to efficiently give the best alignment with another. My brute force shifting and subtracting from the main image is slow... Most programs I have seen align a selected sub-image, then shift the whole image/array (without rotation, although that would be desirable)
If I understand you well, you essentially want to estimate a shift between two images. I have some code that can do that. I do not intend to include that in nd_image for now, but I can send you the code.
My _main_ objective is to stack progressively-longer-exposure 8-bit images into 16-bits, with the clipped pixels of longer exposures ignored in the summing process. The value of each pixel must be weighted inversely proportionately to it's exposure length (so shorter exposures "fill in" the clipped areas of the long exposures).
So: 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 operations. Cheers, Peter