I was trying to retrieve an image using preview image web service, it was mentioned in here that we would need url in the form of "[URL template]/[Image variable name].png" to access the image. It was also mentioned that for obtaining "[URL template]", I need to use the granule search web service and look for a link that points to an "image/png", but when I try to search granule for the dataset_id : "PODAAC-ASOP2-25X01" (this is the dataset you specified in sample url) I did not find any link for "image/png".
All I could find was links to metadata, OpenDap, FTP url etc but not any image url.
Please look into this.
P.S: link for granule search results is http://podaac.jpl.nasa.gov/ws/search/granule/?datasetId=PODAAC-ASOP2-25X01&format=html