How do I override/theme Views REST Export display field? I have a REST Export view display setup in Drupal 8, delivering node fields. 

The challenge: I want to theme/tweak/alter the output of JSON or HAL_JSON for and image field. Currently, it's rendering this in JSON:

"field_feature_image":"  &lt;a href=\"http:\/\/mysite.com\/app\/sites\/default\/files\/images\/feature\/huygens.jpg\"&gt;&lt;img src=\"http:\/\/christopherstevens.cc\/app\/sites\/default\/files\/styles\/large\/public\/images\/feature\/huygens.jpg?itok=cmIzLkJp\" width=\"480\" height=\"480\" alt=\"Huygens Probe (Illustration)\" typeof=\"foaf:Image\" class=\"image-style-large\" \/&gt;\n\n&lt;\/a&gt;\n"


I would prefer it to look like this (taking out all the HTML):

"field_feature_image":"http:\/\/mysite.com\/app\/sites\/default\/files\/images\/feature\/huygens.jpg"


Where's the best place to start? I don't see any views theme options when specifying a REST Export display. Should I create a module of some sort? Is there a theme option?
Here's one option: 

Add a new relationship in the view for the field (field_feature_image in your case)

Add new field for "File: URI" using this new relationship

Use the File URI formatter, and also enable the "Display the file download URI" option

This method may not be ideal for fields with multiple values. I am still working out the best method to do that using the core tools in Drupal 8.