  We present JHK surface photometry of 15 highly inclined, late-type (Sab-Sc)
spirals and investigate the quantitative effects of dust extinction. Using the
(J - H, H - K) two-color diagram, we compare the color changes along the minor
axis of each galaxy to the predictions from different models of radiative
transfer. Models in which scattering effects are significant and those with
more than a small fraction of the light sources located near the edge of the
dust distribution do not produce enough extinction to explain the observed
color gradients across disk absorption features. The optical depth in dust near
the plane as deduced from the color excess depends sensitively on the adopted
dust geometry, ranging from tau = 4 to 15 in the visual band. This suggests
that a realistic model of the dust distribution is required, even for infrared
photometry, to correct for dust extinction in the bulges of nearly edge-on
systems.
