[magick-users] Averaging 8x8 blocks

[Wolfgang Hugemann]

Hello,

I would like to average the bit values in the 8x8 cells of a JPEG-coded 
photograph:

If the original is, say, 1024 x 768, then I would like to downsize it to 
128 x 96 pixels, each of the pixels representing the average value of 
one of the original 8x8 JPEG cells.

Can this be achieved by ImageMagick?

And if so: could I also determine the variance in the 8x8 cells?

Greetings from Germany
Wolfgang Hugemann