web page image sizes work with "_blank' but not with target=""

It would be better for me to clearly understand your question, or at least your objectives, which my frenchglish doesn't help.

It would seem that you're fine with the page opening in _blank, but that the problem is that each time you open a new image, it generates a new tab. If this is your problem, use a unique target window name, such as foo, or _foo, to name your new target. This way, each new opening will use the same unique window, and therefore the same tab.

By convention, and although not formalized, it's customary to use the generic term _new, but you can just as easily use myPersonalImageViewer, or _myPersonalImageViewer, however, as with every new tab opened, beware of Javascript-related attacks, so it's advisable to minimize them by adding the rel="noopener noreferrer" attribute https://developer.mozilla.org/fr/docs/Web/HTML/Attributes/rel/noopener, https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/rel/noreferrer

Please, feel free to refine your question if necessary !

Is this what you're attempting to do?  See screenshot.

when I display the same image in my index page it opens a widow where it reverts to its native size...

By @Peter35508677swvo

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Identify the CSS selector name for your modal window and add this.

YourModal img {

max-width: 100%;

}

This will constrain modal images to the parent container's size.

Hope that helps.  If not, post back with the URL to your online page.

Alternatively, has anyone built a blank template that includes a close button that can receive a tag that for an image?

By @Peter35508677swvo

Sounds like a page overlay modal would be a better option or does the image specifically have to open in a new pop open window which is seperate from the window in which the onclick event was initiated, for some reason?

Please supply an online link to the page so that we can see what you have done.