Restores WordPress default functionality prior to version 4.7 where image ALT attributes were automatically generated and put into the HTML code. The ALT attributes were generated from the Caption (if it exists) else from the Title (if it exists) of the image in the Media Library. This plugin utilises Titles in generating ALT text, but does not utilise Captions. The Title used by this plugin, is the main Title of the image as found in the Media Library, not the HTML TITLE attribute of the image (that is something else, which this plugin ignores).

Automatic image ALT attributes

This feature is a time saver for me as my site is image oriented.

Thanks

Automatically generates ALT attributes in image HTML. Restoring WordPress < 4.7 functionality.

Taylor Callsen

Automatically populates Alt and Title tags for images featured in posts and pages, pulling directly from the values set in the Media Library. This makes it easy to manage your image metadata centrally in one place (the Media Library). Plugin also supports the ability to override the Alt/Title tag Media Library values by placing an Alt/Title tag directly on the attachment in the WordPress WYSIWYG Editor.
Tag population only occurs when viewing the post or page, and does not occur in the WYSIWYG editor.

Auto-populate Image ALT Tags from Media Library

Automatically populates Alt and Title tags for images using the values set in the Media Library.

Automatic image ALT attributes vs Auto-populate Image ALT Tags from Media Library