Recall from previous post, http://wp.me/phWh4-qm I played a bit with using convex polygons and buffers to control noisy backgrounds behind text, ala:

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I was tired of doing this in the GUI in QGIS, so I wrote some simple code to do it in PostGIS.

CREATE TABLE cm_label_cvx AS
WITH buffer_cvx AS (
    SELECT ST_Buffer(ST_ConvexHull(geom), 250) AS geom FROM cm_label_med)
    SELECT ST_Union(geom) FROM buffer_cvx;