Google Earth Engine Speckle Noise Reduction

spk.js

var sentinel1 = ee.ImageCollection('COPERNICUS/S1_GRD');
var poly = ee.Geometry.Polygon(
        [[[-95.83648681640625, 29.561512529746743],
          [-95.042724609375, 29.57345707301757],
          [-95.02899169921875, 30.099989515377835],
          [-95.82275390625, 30.10711788709236]]]);
var spatialFiltered = sentinel1.filter(ee.Filter.eq('instrumentMode', 'IW')).filterBounds(poly)
                               .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV'))
                               .select('VV');
var image = spatialFiltered.filterDate('2017-08-25', '2017-09-05').mosaic().clip(poly);
print (image);

//Extended Directional Smoothing
function eds(image) {
  // Create a list of weights for a 3x3 kernel.
  var dir1 = ee.List([[0, 0, 0], [0.5, 0, 0.5], [0, 0, 0]]);
  var dir2 = ee.List([[0, 0.5, 0], [0, 0, 0], [0, 0.5, 0]]);
  var dir3 = ee.List([[0, 0, 0.5], [0, 0, 0], [0.5, 0, 0]]);
  var dir4 = ee.List([[0.5, 0, 0], [0, 0, 0], [0, 0, 0.5]]);
  //Convolve directional kernels with the image
  var d1 = image.convolve(ee.Kernel.fixed(3, 3, dir1, -1, -1));
  var d2 = image.convolve(ee.Kernel.fixed(3, 3, dir2, -1, -1));
  var d3 = image.convolve(ee.Kernel.fixed(3, 3, dir3, -1, -1));
  var d4 = image.convolve(ee.Kernel.fixed(3, 3, dir4, -1, -1));
  //Absolute value of the difference from convolved image with original values
  var D1=(d1.subtract(image)).abs();
  var D2=(d2.subtract(image)).abs();
  var D3=(d3.subtract(image)).abs();
  var D4=(d4.subtract(image)).abs();
  //Pick min pixel value based on abs difference(first input) using reducers
  var Dd=ee.ImageCollection([[D1,d1],[D2,d2],[D3,d3],[D4,d4]]);
  var reducer =ee.Reducer.min(2);
  //Select the second input to the reducer
  var v = Dd.reduce(reducer).select('min1');
  return v;
}



function msd(denoised,original) {
  var diff = denoised.subtract(original);
  var sq= diff.pow(2);
  var meanDict = sq.reduceRegion({
  reducer: ee.Reducer.mean(),
  geometry: poly,
  scale: 20 ,
  bestEffort:true
  });
  return meanDict;

}

//plane smoothing to remove speckle noise
var smooth = ee.Image(image.focal_median(100, 'circle', 'meters'));
var image_spk = eds(image);


print (image_spk);
Map.centerObject(poly, 10);

Map.addLayer(image,{min:-30,max:30},'sentinel 1 raw');
Map.addLayer(smooth,{min:-30,max:30},'sentinel 1 smooth');
Map.addLayer(image_spk,{min:-30,max:30},'sentinel 1 EDS');

var msd1=msd(smooth,image);
print (msd1);
var msd2=msd(image_spk,image);
print (msd2);

Great！What is the full name of this filter？

Have you published a paper with this code? What is the title of the paper?

@mozong2018 this paper is probably what you're looking for:
https://www.researchgate.net/publication/250755875_Enhanced_Directional_Smoothing_Algorithm_for_Edge-Preserving_Smoothing_of_Synthetic-Aperture_Radar_Images