Perform Band Ratio in GEE

Question

I was new in GIS and Google Earth Engine, i want to perform band ratio for mapping Ferric and Ferrous using ASTER L1T Radiance. I want to use band 2/1, 5/3, and 1/2. How to perform it in Google Earth Engine? I was tried but i don't know if this true or not.

var dataset = ee.ImageCollection('ASTER/AST_L1T_003')
  .filterDate('2019-03-01', '2019-03-05')
  .filterBounds(Boundary);
Map.setCenter(107.62160048828126,-7.087318840287035, 12);
  Map.addLayer(dataset, {bands: ['B01', 'B02'], min: 0.0, max: 255.0}, 'ASTER1');
  Map.addLayer(dataset, {bands: ['B05', 'B3N'], min: 0.0, max: 255.0}, 'ASTER2');
  Map.addLayer(dataset, {bands: ['B02', 'B01'], min: 0.0, max: 255.0}, 'ASTER3');
  Map.addLayer(Boundary);

Answer 1

try the User Guide, is excellent. userguide

First of all, your dataset is a ImageCollection not an image. So make sure you grab an image. There are different ways to compute band ratios. One of them is with expressions:

    var asterImage = ee.Image('ASTER/AST_L1T_003/20190304174953')
var bandRatio = asterImage.expression(
    'band1 / band2', {
      'band1': asterImage.select('B01'),
      'band2': asterImage.select('B02')});