@arunnbabu81 If you’re willing to replace all your instances of [img[...]] with a macrocall or a template transclusion, @TW_Tones’s approach would definitely be quickest, and you don’t need 5.3.0 functionality to do it. Here’s a super-quick mockup you can test at tiddlywiki.com:
\define img(source)
<$list filter="[[$:/config/image-mode]text[popup]]"
emptyMessage="""<$image source=<<__source__>> />""">
<$button popup=<<qualify "$:/state/$source$">>>
Pop me up
</$button>
<$reveal type="popup" state=<<qualify "$:/state/$source$">>>
<div class="tc-drop-down">
<$image source=<<__source__>> />
</div>
</$reveal>
</$list>
\end
\define mode()
<$action-listops $tiddler="$:/config/image-mode" $field="text" $subfilter="+[toggle[popup]]" />
\end
<<img "Motovun Jack.jpg">>
<$button actions=<<mode>>>image mode</$button>
I used a macro mostly for the single-tiddler demonstration, but you could just as easily make the img macro a template tiddler and call it with {{Motovun Jack.jpg||img}}. I didn’t do any particular styling on the popup, but you could style it to your liking (or use a modal instead) and add additional macro parameters for other $image attributes.
You’d want to move the “image mode” button and the mode macro definition to a separate tiddler for your view toolbar button. The sample button is currently toggling a global config tiddler, but you could alter it to modify <<currentTiddler>> instead, if you want per-tiddler control.
If you do want to go this route, I’d recommend using the Commander plugin to search-and-replace the wikitext in all the tiddlers where you want this alternate behavior.
First button was adapted based on section editor and some of Charlie’s works. Second button was adapted from TW_Tones button he had shared before in this forum.