I would like to reclass MODIS imagery using GEE. The aim is to reclass an image (i) using the day before (index i-1) and the day after (i+1), and then (i-2 and i+2). I’ve tried with .expression and .where, but I can’t be able to solve the issue. My imagery has 3 values ( 1, 2 and 3), so I need to reclass 1 looking through the consecutive images.

Here, my reproducible script:

var ROI=    ee.Geometry.Polygon(
        [[[-121.96115141166754, 50.173193895476736],
          [-121.96115141166754, 45.64072456168797],
          [-117.63253813041754, 45.64072456168797],
          [-117.63253813041754, 50.173193895476736]]], null, false);

var reclassify = function(image) {
  var b0 = image.select('NDSI_Snow_Cover')
  var b1 = image.select('Snow_Albedo_Daily_Tile_Class')
  var shift0 = b0.where(b0.gt(40), 3).where(b0.lte(40), 2).unmask(-9999);
  var shift1 = b1.remap(
  [101, 111, 125, 137, 139, 150, 151, 250, 251, 252, 253, 254], 
  [ 1,   1,   2,   2,   2,   1,   1,   1,   1,   1,   1,   1 ], null);
  var reclassified = shift0.where(shift0.eq(-9999).and(shift1.eq(2)),2).where(shift0.eq(-9999).and(shift1.eq(1)),1).rename('remapped')
  return reclassified
};

var terraCollection = ee.ImageCollection('MODIS/061/MOD10A1').filterBounds(ROI)
      .sort('system:time_start', true).filterDate('2016-04-01', '2017-05-01').map(reclassify)
    print(terraCollection)
    
    var list0 = terraCollection.toList(terraCollection.size());

    var collectionSize = terraCollection.size().getInfo();
    
    var temporalFilter = ee.List([]);
    for (var i = 3; i <= collectionSize-1; ++i){
     var b0 = ee.Image(list0.get(i-0)).select('remapped');
     var b1 = ee.Image(list0.get(i-1)).select('remapped');
     var b2 = ee.Image(list0.get(i+1)).select('remapped');
     var b3 = ee.Image(list0.get(i-2)).select('remapped');
     var b4 = ee.Image(list0.get(i+2)).select('remapped');
     var shift0 = b0;
     var shift1 = shift0.expression( '(b0 == 1) && (b1 == 3) && (b2 ==3) ? 3 : b0', {'b0': shift0, 'b1': b1, 'b2': b2});
     var shift2 = shift1.expression( '(b0 == 1) && (b1 == 2) && (b2 ==2) ? 2 : b0', {'b0': shift1, 'b1': b1, 'b2': b2});
     var shift3 = shift2.expression( '(b0 == 1) && (b3 == 3) && (b4 ==3) ? 3 : b0', {'b0': shift2, 'b3': b1, 'b4': b2});
     var shift4 = shift3.expression( '(b0 == 1) && (b3 == 2) && (b4 ==2) ? 2 : b0', {'b0': shift3, 'b3': b1, 'b4': b2});
    temporalFilter = temporalFilter.add(shift1.rename('remapped').copyProperties(b0, ['system:index','system:time_start']));
    }
    
    var temporalCollection = ee.ImageCollection.fromImages(temporalFilter)
    print(temporalCollection)

    var list1 = temporalCollection.toList(temporalCollection.size());

    var k = '01'; 
    var dateFilter = '2016_04_' + k;
    
    var img0 = list0.filter(ee.Filter.eq('system:index', dateFilter)).get(0);
    var img1 = list1.filter(ee.Filter.eq('system:index', dateFilter + '_' + dateFilter)).get(0);
    
    var imgsnow0 = ee.Image(img0).reproject('EPSG:32719', null, 500);
    var imgsnow1 = ee.Image(img1).reproject('EPSG:32719', null, 500);
    Map.addLayer(imgsnow0.clip(ROI), {min:1,max:3, palette: ['4de0e0','3d4852','ffffff']}, 'MODIS Terra',true);
    Map.addLayer(imgsnow1.clip(ROI), {min:1,max:3, palette: ['4de0e0','3d4852','ffffff']}, 'MODIS Filter',true);