workaround.js

      if(!supportsfilter){
        workaroundImage.filter([
          {
            filter : 'saturation',
            parameters :
            {
              strength : post.parameters.filter.parameters.saturation
            }
          },
          {
            filter : 'gammaRGB',
            parameters :
            {
              amplitudeR: 1.6,
              exponentR: 1.3,
              offsetR: post.parameters.filter.parameters.gammaR,
              amplitudeG: 1.6,
              exponentG: 1.3,
              offsetG: post.parameters.filter.parameters.gammaG,
              amplitudeB: 1.6,
              exponentB: 1.3,
              offsetB: post.parameters.filter.parameters.gammaB
            }
          },
          {
            filter:"vignette",
            parameters:{
              size:post.parameters.filter.parameters.vignette/2,
              amount:0.14,
              centerX:0.5,
              centerY:0.5,
              r:0,
              g:0,
              b:0
            }
          }
          ], function(filteredImageData) {
            setTimeout(function() {
              $('.ut-image').css('background-image','url('+filteredImageData.url+')');
            }, 0);
        });