Google Earth Engine Water Mask and keep non water area

Question

I'm pretty new at GEE.

I want to mask only the water areas for my study area. I want non-water areas to retain their pixel values. For this I detected and masked water areas with NDWI. However, after masking, I cannot show non water pixels and masked pixels (water) in the same image. I see black image for areas without water

I converted my image to 8 bit because it calculates the NDWI index more accurately.

This is my code : https://code.earthengine.google.com/85e1ed5971f860ef8f75ac46342f9f5f

var geometry = 
    /* color: #98ff00 */
    /* shown: false */
    /* displayProperties: [
      {
        "type": "rectangle"
      }
    ] */
    ee.Geometry.Polygon(
        [[[28.115704913382, 36.89857549006249],
          [28.115704913382, 36.681919654361074],
          [28.33371486211247, 36.681919654361074],
          [28.33371486211247, 36.89857549006249]]], null, false);


var s2 = ee.ImageCollection('COPERNICUS/S2_SR');

var rgbVis = {
  min: 0.0,
  max: 3000,
  bands: ['B4', 'B3', 'B2'],
};
 
var filtered = s2
  .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 30))
  .filter(ee.Filter.date('2021-08-25', '2021-08-29'))
  .filter(ee.Filter.bounds(geometry))
  .select('B.*');

var composite = filtered.median().clip(geometry) ;
print(composite)
// Display the input composite.
Map.addLayer(composite, rgbVis, 'image');


///Rescale to 8 bits

var composite = composite.unitScale(0, 65535).multiply(255).toByte();

///NDWI/////

var ndwi =
    composite.normalizedDifference(['B3', 'B8']).rename('NDWI');
Map.addLayer(
    ndwi,
    {palette: ['red', 'yellow', 'green', 'cyan', 'blue']},
    'NDWI');
    
    

// Create NDWI mask
var ndwiThreshold = ndwi.gte(0.0);
var ndwiMask = ndwiThreshold.updateMask(ndwiThreshold);
Map.addLayer(
    ndwiThreshold,
    {palette:['black', 'white']},
    'NDWI Binary Mask');
Map.addLayer(ndwiMask, {palette:['blue']}, 'NDWI Mask');

 
var mask = ndwiThreshold.eq(0); 
var S2_2 = composite.updateMask(mask); 
print(S2_2)
Map.addLayer(S2_2, rgbVis, 'image2');

Answer 1

One quick option: the 8 bits image used for NDWI must be different to image that you want to mask, so:

//Keep 8 bits for NDWI

///Rescale to 8 bits as new var (e.g. composite2)

var composite2 = composite.unitScale(0, 65535).multiply(255).toByte();

///NDWI/////

var ndwi =
    composite2.normalizedDifference(['B3', 'B8']).rename('NDWI');
Map.addLayer(
    ndwi,
    {palette: ['red', 'yellow', 'green', 'cyan', 'blue']},
    'NDWI'); 

code example here