code: function (inData, outData, width, height, options) {
          options = defaultOptions(options, {strength: 1});
          var a = clamp(options.strength, 0, 1) * 5;
          convolve3x3(inData, outData, width, height,
              [
                  [ 0, -a, 0],
                  [-a, 0, a],
                  [ 0, a, 0]
              ],
              false, true);
      }
docs: A 3x3 Cross edge-detect