The only thing I was able to figure out cross-browser, and it's already in there, was this:

https://github.com/kristopolous/BOOTSTRA.386/blob/master/les...

    img {
     display: none;
     -webkit-filter: contrast(800%);
     -moz-filter: contrast(1000%);
     filter: contrast(1000%);
     -o-filter: contrast(800%);
     -ms-filter: contrast(800%);
    }

(In fact, I don't know what that display:none is doing there now ... I'll have to look into it)

There may be some brilliant visual hack to get images to look more faithful ... but this was the best I could figure out.