When downloading an image from a URL, by default EasyCatalog will attempt to build a filename based on the format of the URL. Sometimes, however, the filename used is not desirable: for example, the links shown in the Links panel in InDesign will sometimes be meaningless.
EasyCatalog provides a feature to specify a file naming strategy. In the Picture Options, you can append a storage strategy inside of [$ brackets $] at the end of the URL. For example:
When Easycatalog sees this [$ … $] at the end of the URL, instead of building the local storage path based on the URL content it will use whatever is between the [$ and $]. In this example, each downloaded image’s filename will be the contents of the ImageName field.
To append a file extension, include this in the storage schema: