The CDI evaluates the creative device behind a thumbnail — the metaphor, the wink, the conceptual connection chosen — not its technical attributes. It is an editorial metric: it doesn't come from the Koh & Cui model and it changes neither the ELM Score nor the Clickability Index. It builds on the idea of associative distance from the vRAT framework (Olteţeanu & Zunjani, 2020).
It is reported only when the asset uses an identifiable creative device — a visual joke, a reference, a twist. A generic thumbnail without that device omits the section.
How far is the idea from obvious or expected territory? It is expressed as a rating of Originality.
How quickly is it understood, without further explanation? It is expressed as a rating of Simplicity.
It goes far from the obvious and is understood at first glance. The ideal.
It's understood, but stays close to the expected: safe, not very memorable.
It takes a risk and goes far, but it's hard to understand. The clarity needs reinforcing.
It neither surprises nor connects. The worst case.