[Image-SIG] Performance for image processing in Python

[Son Hua]

Hi everyone,

I'm quite new Python here. Recently I wrote an image mosaicking 
application in Python (using Numpy library). It turns out that the 
performance is quite terrible. For example, a mosaic of 7 images, each 
800x600, the output size is about 8000x2000. Each output pixel is 
sampled from the source images using bilinear interpolation according to 
the inverse homography. The running time is nearly 1 hour.

State-of-the-art commercial mosaicking software (written in C) runs the 
above examples in less than 10 seconds!!!

I wonder how is other Python image processing applications' performance? 
Do we always need to implement slow functions in C? E.g., I suppose to 
reimplement the bilinear interpolation in C, as it is called million 
times in Python, which is slow.

Thank you.