record pixel value with Python script

[DPod]

A scripting newbie question...

I'd like to write a Python script for ArcGIS 10.x (ArcPy or Python 2.6.5) that would record the pixel value for all pixels in a raster. Furthermore, I'd like to only record a given value once in the results. For example, if there are 23 values of 180 overall, only record one instance of that value.

The raster in question is 4-band (6017 x 7715 pixels) so the results would have to include values for all pixels in each band, recorded separately by band. Ideally I'd like to write to an Excel file or at least a .csv file.

Any help and examples would be greatly appreciated.