1. A computer-implemented method comprising: identifying image regions within an image, wherein each of the image regions is associated with a region identifier, the region identifier corresponding to a rendered color for that image region, and wherein the image region comprises image pixels and a region boundary, the region boundary defining a boundary of the image region based on the rendered color for the image region; generating a representation of the image using a Gaussian blur filter, wherein the representation of the image characterizes each of the image regions and wherein, for each image region, the representation of the image indicates weighted values of the image pixels of the image region according to a distance between the image pixels of the image region and the region boundary; determining annotation leader locations for the image based on, at least, the weighted values of the image pixels in the representation of the image; generating annotation leaders at the annotation leader locations; and providing the annotation leaders and the image.