6. The computer-implemented method of claim 5 , wherein the query descriptors comprise at least: a large scale subset of the query descriptors characterizing larger scale features of the query content; and a small scale subset of the query descriptors characterizing smaller scale features of the query content.
5. The computer-implemented method of claim 1 , further comprising: determining that a second proportion of the query descriptors corresponding to the subset of the content descriptors at each respective scale is greater than a second proportion threshold corresponding to the respective scale; and selecting the content piece for inclusion in the matching content subset.