figure:hover img {
  opacity: 1;
  -webkit-animation: flash 1.5s;
  animation: flash 1.5s;
}
@-webkit-keyframes flash {
  0% {
    opacity: .4;
  }
  100% {
    opacity: 1;
  }
}
@keyframes flash {
  0% {
    opacity: .4;
  }
  100% {
    opacity: 1;
  }
}