I know I can use ’embed’ or another method to link to a single image, but this doesn’t work if the photo is private.

Actually, hotlinking an image will work regardless of whether a photo is private – you don’t have to embed it. I assume you are talking about “Flickr embeds” – those wouldn’t work for a page on Flickr with a private photo, but there is nothing preventing you from seeing the same photo while not on the page.

When you are logged into Flickr, you can right click on a photo and “Inspect” it in Chrome. You will see a couple of URLs displayed in the Inspector pointing to the JPG files. You can use the link to the JPG file in an <img> tag on your site to hotlink the image.

As an example, this is a Flickr page: https://www.flickr.com/photos/sayontan/46768215531/. This could have been private, in which case you wouldn’t be able to see it. But this is the actual photo in the page: https://live.staticflickr.com/7881/46768215531_eebd9f6196_k.jpg. Even if private, you would be able to see this – that is how Photonic displays private photos as well.

I don’t intend to add support for pulling a single photo without any other information – it is inefficient to do so through a plugin.

If you still want to use the plugin, you can consider using CSS to hide the header and the caption:

.photonic-flickr-stream h3 { display: none; }
.photonic-flickr-stream .wp-caption-text { display: none; }

The above has 2 shortcomings:

1. The end result might look a bit jarring, because this depends on the styling of your theme.
2. Photonic will link the photo on your site to the Flickr page for the photo – that is going to be a problem for you if the page is private.

No worries. Let me know if you require any additional help.