I'm currently using this
Control Adapter that will append or insert an 'alt=""' tag to comply with the WCAG F38 test that indicates decorate images should have alt tags.
So I have deployed WSP file on local. and tested using WAVE chrome extension, so I found that some image tag still don't have alt attribute.
Means it will skips some Image tag to add alt attribute in SharePoint Master Page.
I'm facing this issue on production environment.