Node image instead of pointer icon in openlayers map
output the image's URL in your view which supplies data to your map.
create a new openlayer style, and for the marker graphic, give it your field name enclosed in ${}.

eg. add field_image to your view, set it to output 'url to file'
then add a new style and tell it the marker graphic url is ${field_image} and select an image style (eg. thumbnail)

use this new marker style on your overlay and you'll see the image show up as a marker icon.