doxygen help has broken image for examples that have no image
If VTK Examples linked in the class documentation have no images, you'll get a broken image.
See for instance https://vtk.org/doc/nightly/html/classvtkImageData.html#details
For PNGWriter or ImageIterator.
These examples could be referred with a simple link (instead of a link with an image) or using a generic "noimage" png such as https://www.google.com/search?q=noimage+png&rlz=1C1CHBF_enUS911US911&oq=noimage+png&aqs=chrome..69i57j0i22i30l6j0i10i22i30.2770j0j7&sourceid=chrome&ie=UTF-8