Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Previously, such measures have been used in a variety of vision processing tasks, including image enhancement and motion estimation [16], video segmentation [12], pattern categorization [34] and activity recognition (although not generic anomaly detection) [10,13,11].
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