Image Link Attributes
This module allows administrators to add custom attributes like "Target", "Class", and relational attributes (e.g., for lightboxes) to links generated from image fields. It also provides an option to link to an image style variant instead of the original file.
About
The Image Link Attributes module extends Drupal's default image field so that when an image is linked, additional attributes can be applied to the link for "Target", "Class" and Relationship (ie: rel="lightbox-series").
* Works with image fields and responsive image fields.
Usage
Install the Image Link Attributes module, then navigate to the display settings page of the content type with the image field that you would like to adjust. When you set the image to link to content or file, the additional settings will become available.
Link to an Image Style variant
From version 8.x-1.8 and newer, you can choose an Image Style variant instead of being confined to linking to the original file. To choose an Image Style variant, click the "Link to alternate Image Style" checkbox on the Image Field — Manage display settings form; then from the drop-down list of image styles choose the style you would like the field to link to.
Known Issues
None.