Fast Gaussian blur: O(1) per pixel (!?)

Just found this:

[size=120]Extended Binomial Filter for Fast Gaussian Blur[/size]

Key Features
• Constant complexity O(1) per pixel, independent of the blur radius.
• Minimum pixel readouts, also independent of the blur radius.
• Computation as simple (and fast) as box blur.
• Adequate approximation selectable to the desired accuracy.