  The recent advent of the Event Horizon Telescope (EHT) has made direct
imaging of supermassive black holes a reality. Simulated images of black holes
produced via general relativistic ray tracing and radiative transfer provide a
key counterpart to these observational efforts. Black hole images have a wide
range of physically interesting image structures, ranging from extremely fine
scales in their lensed "photon rings" to the very large scales in their
relativistic jets. The multi-scale nature of the black hole system is therefore
suitable for a multi-scale approach to generating simulated images that capture
all key elements of the system. Here, we present a prescription for adaptive
ray tracing, which enables efficient computation of extremely high resolution
images of black holes. Using the polarized ray-tracing code ipole, we image a
combination of semi-analytic and GRMHD models, and we show that images can be
reproduced with mean squared error of less than 0.1% even after tracing 12x
fewer rays. We then use adaptive ray tracing to explore properties of the
photon ring. We illustrate the behavior of individual subrings in GRMHD
simulations, and we explore their signatures in interferometric visibilities.
