  We describe the Blacklight code, intended for post-processing
general-relativistic magnetohydrodynamic simulation data. Beyond polarized ray
tracing of synchrotron radiation, it can produce a number of outputs that aid
in analyzing data sets, such as maps of auxiliary quantities and false-color
renderings. Additional features include support for adaptive mesh refinement
input, slow-light calculations, and adaptive ray tracing. The code is written
with ease of use, readability, and transparency as primary objectives, while it
still achieves high performance. Blacklight is publicly available and released
into the public domain.
