Handling a long description where a 'complex' image appears as a thumbnail link

Hello all,

I would appreciate whether this approach makes sense. We have a small number of images on our website which ideally need a long description. This is fine for the pages they reside on as the dominant large image, but in some cases, those images are reduced to small thumbnails and blocks of text on other pages, (as a call to action, alongside other CTAs about similar topics) that crosslink to the destination page, where the larger version of the image resides, and where I would ideally provide a long description.

To me it makes more sense to mark them up as decorative where they appear as thumbnail links elsewhere and add a long description where the image appears in full on the actual page. In nearly all cases it's nearly impossible for me to add contextual value within alt text limits. In this example, 'complex' images are also being used as an accompaniment to some CTA text.

Has anybody else come up against this, and does this approach make sense? So sorry if this is all obvious to you all, and I appreciate this isn't a technical question!

With best wishes
Louise

This email (and attachments) are confidential and intended for the addressee(s) only. If you are not the intended recipient please notify the sender, 
delete any copies and do not take action in reliance on it. Any views expressed are the author's and do not represent those of IOP, except where specifically 
stated. IOP takes reasonable precautions to protect against viruses but accepts no responsibility for loss or damage arising from virus infection. 
For the protection of IOP's systems and staff emails are scanned automatically. 

Institute of Physics. Registered charity no. 293851 (England & Wales) and SCO40092 (Scotland)
Registered Office:  37 Caledonian Road, London, N1 9BU