Image titles - what is best practice?

[sopuli]

Hello again,

I have gathered all my images (screenshots mainly) in one topic and use <conref> to refer to them wherever I need them.

I want to publish a) WebHelp and b) PDF.

In the WebHelp scenario, I don't want the image titles to appear (because the images are self-explanatory in their context).
In the PDF, I need the image titles, because I also want to create an image index at the end.

What is the best practice way to deal with the titles in order to achieve the described outcome in the transformations?

Thank you!