Correct use of Schema.org "ImageObject"

Question

I have doubts about the correct use of schema ImageObject.

I have a small image and a link to view it in larger size, but I don’t know exactly which of these three forms is the right one.

<span itemprop='image' itemscope itemtype='http://schema.org/ImageObject'>
<a href='big_1280x720.jpg' itemprop='contentUrl'><img src='small_90x60.jpg' itemprop='image'></a>
</span>

<span itemprop='image' itemscope itemtype='http://schema.org/ImageObject'>
<a href='big_1280x720.jpg' itemprop='image'><img src='small_90x60.jpg' itemprop='thumbnailUrl'></a>
</span>

<span itemprop='image' itemscope itemtype='http://schema.org/ImageObject'>
<a href='big_1280x720.jpg' itemprop='contentUrl'><img src='small_90x60.jpg' itemprop='thumbnailUrl'></a>
</span>

Solution

The third one removing the first occurence of itemprop='image' is the right one.

<div itemscope itemtype='http://schema.org/ImageObject'>
  <a href='big_1280x720.jpg' itemprop='contentUrl'>
    <img src='small_90x60.jpg' itemprop='thumbnailUrl'>
  </a>
</div>

Comments

[Nash Bridges]

If an image is a part of a bigger scope (e. g. a movie), then removing itemprop="image" will extract it from the current scope to the root one. Check developers.google.com/structured-data/testing-tool

[vhs]

Also compare against the Yandex structured data tool for balance.

[vhs]

Examples do not cover use of thumbnailUrl as asked in the question.