CSS image opacity?

my pictures are slightly transparent whether I set transparency or not. Even with opacity: 1.0. But it works with everything else opacity settings. (At 0.2 it becomes much more transparent). Why?

//.gallery {
  position: absolute;
  left: 60;
  top: 130;

.gallery img {
  width: 50%;
  opacity: 1.0;

And how do I get off these points to the left of the pictures?

The dots appear because the images are in inside an unordered list. You can set the list style type via CSS: list-style-type - CSS Reference