tr= getParam( 'timerange', '2008-01-01', 'timerange to load' )
wb= getParam( 'color', 'white', 'the color to count', ['white','black'] )
ds= getDataSet( 'http://autoplot.org/autoplot/autoplot/autoplot/data/pngwalk/product_$Y$m$d.png?channel=greyscale', tr )
if wb=='white': iwb=255 
else: iwb=0
r= where( ds.eq( iwb ) )
print r.length()