We perform noise measurement using a transmission target placed
on top of a uniform light box. The transmission target, designed
by DxO Labs, is made of a plate of thick black plastic with
precision-drilled holes which are equipped with a range of
neutral density filters designed to absorb the light identically
for all wavelengths. The filters are made of pure optical glass
with no structures that can be measured as noise. (While other
image quality measurement solutions make use of printed targets,
we believe such targets are inappropriate for noise measurement
testing, as the intrinsic noise pattern of the print paper may
be recorded by the tested camera and then confused with the
camera’s own noise pattern.) We place high-density filters on
neighboring positions to limit reciprocal illumination of the
patches.The light box (placed behind the target) is composed of
two fluorescent daylight spectrum tubes with a diffusing sheet
on top, achieving a perfect uniformity on each filter. The
luminance is about 150