Hi Alex, It is correct that there is an amount of work duplicated, if you do an identical interpolation operation on several arrays. There is currently no way to avoid this. This can be fixed and I will have a look to see how easy that is to do. If it is not easy to factor out that part of the code, I will most likely not be able to spend the time to do it though... You could at least use the map_coordinates function that will allow you to use a pre-calculated coordinate mapping. There will still be duplication of work, but al least you avoid the duplication of the calculation of the coordinate transformation. Peter

Hi all.   I've been looking at numarray to do some image processing. A lot of the work I do deal with transforming images, either with affine transformations, or vector field. Numarray seems somewhat well equiped to address these issues, but I am concerned about one aspect. It seems that the transformation code (affine_transforrm and geometric_transform) computes input coordonates for every output coordinate in the resulting array. If I have an RGB image for which the transformation is the same for all 3 RGB channels, I would assume that this will triple the workload unncessarily. It might have a dramatic effect for the geometric transformation which will most often be slower then affine. Is there any way around this, e.g. is it possible to specify numarray to use the same interpolation coefficients for the last "n" dimention of the array, or to tell numarray to only compute interpolation coefficients and apply those seperatly for each channel?   thx for any help / info.   alex.