This tag makes value of an object editable when editing session is active. Mostly used for article.title and element fields. If editing session is not active it displays the value of the field. Only one editable per field should exist on page.
{% editable object.field %}
In case of element image type field it has an additional parameter target_width defining the target size of image that should be saved from the list of automatically generated image sizes. Obtained image size is smallest possible image that will not upscale for the given size. If non-upscaling image is not found, the biggest one (original) is returned instead.
{% editable element.image target_width="600" %}
Current automatically generated image sizes list by width is (may change in future): original, 600, 1280, 2048. If original is smaller than given size, bigger sizes for images are not generated.