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[sn6uv]

Fixes #492

[sn6uv]

This is clashing with $OutputSizeLimit slightly, e.g.

   5. TEST DominantColors[img, 3, "CoverageImage"]
----------------------------------------------------------------------
Test failed: DominantColors in Reference of built-in symbols / Image[] and image related functions.
DominantColors[img, 3, "CoverageImage"]
Result: {-Image-, <<1>>, -Image-}
Wanted: {-Image-, -Image-, -Image-}

My guess is because the size of the image is being used somehow rather than the size of its textual representation? Also affects the web frontend: @poke1024