  Multimode squeezed light is an increasingly popular tool in photonic quantum
technologies, including sensing, imaging, and computation. Meanwhile, the
existing methods of its characterization are technically complicated, and in
the best case, deal with a single mode at a time. Here, we demonstrate
experimentally how the squeezing can be measured in multiple spatial modes
simultaneously, using optical parametric amplification and direct detection
followed by modal decomposition based on spatial intensity correlations. We
apply this method to a multimode squeezed vacuum generated via high-gain
parametric down-conversion. We measure the degrees of squeezing and
anti-squeezing for eight strongest spatial modes, obtaining highest squeezing
and anti-squeezing values of $-5.2 \pm 0.2$ dB and $8.6 \pm 0.3$ dB,
respectively.
