RADIAL PROFILE

Creates a 1-D radial profile from un-masked data in the current ROI; output is in the memory. The centre of symmetry is specified, as is the required size of profile pixels. The average values of pixels at each distance range from the centre are calculated.

If variance arrays exist, estimates of the variance for each radial pixel position will be calculated. This is based on the variation of values which contribute to each value. When more than 20 pixels contribute to the radial average the variance ($\sigma^2$) is estimated from the normal equation

$$\sigma = \frac{1}{n-1} \left( \sum^{n}_{i=1} x_i^2 - nm^{2} \right)$$ (7)

where $m$ is the mean value, $n$ is the number of measured values and $x_i$ are the measured values.

(The best estimate for smaller numbers of pixels is under review.)