How to iterate over an array computing mean for each value by looking at its surrounding?

I would like to iterate over an huge array (e.g. 1000x900) and compute for each value a mean with the values in its surrounding (e.g. 3x3) (with and without weighting the values -> have to check the results). I would like to take into account that there could be bigger outliers, during mean computation I would like to ignore or weight outliers extremly low.

Has somebody an idea how to conquer these two problems? Which mean would be suitable and how can I efficiently iterate over an array this way?

Thank you very much in advance.

Greetings baxbear

[Jan]

Fortunately 1000x900 is not huge, but a 7.2MB array only. So start with simple loops. Please explain clearly what "bigger outliers" are and what "weight extremely low" exactly means. The forum cannot decide this for you.