GEE - Image collection to multiband image

Question

I'm new to GEE and got stucked running the followed code. My problem is: Get L5 collection, selecting B7 channel > Mask clouds and shadows based on pixel_qa product > Convert the image collection to a multiband image (only B7) > Export to drive.

The code is running but I can't display the layer or export it. Error message: Cannot add an object of type ComputedObject to the map.

Does anyone know how can I do this?

// Test area
var geometry = /* color: #98ff00 */ee.Geometry.Polygon(
    [[[-49.7, -19.3],
      [-49.7, -18.9],
      [-50.1, -18.9],
      [-50.1, -19.3]]]);

// Function to mask clouds
var maskClouds = function(image){
  var pixel_qa = image.select('pixel_qa');    
  return image.updateMask(pixel_qa.lt(69))
              .clip(geometry);   
};

// Import L5 collections 
var collection5 = ee.ImageCollection('LANDSAT/LT05/C01/T1_SR')
    .filterDate('2008-01-01', '2008-12-31') 
    .filter(ee.Filter.eq('WRS_PATH', 222))
    .filter(ee.Filter.eq('WRS_ROW', 73))
    .select('B7', 'pixel_qa')                               
    .filterBounds(geometry).map(maskClouds);

// Image collection to Image
var empty = ee.Image().select();
var landsat5 = collection5.iterate(function(image, result) {
  return ee.Image(result).addBands(image.select(['B7']));    
    }, empty); 

// Display
print(landsat5)
Map.addLayer(landsat5, {min:0, max:1000})
Map.setCenter(-49.9,-19.1, 10);

// Export image
Export.image.toDrive({ 
  image: landsat5,
  description: 'landsat5',
  region: geometry,
  folder: 'test',
  maxPixels: 1e12,
  scale: 30
});

Answer 1

Casting may solve the error you encountered, but the function you're looking for is imageCollection.toBands().

Answer 2

The iterate function returns a Computed Object, you could see that in the docs. Therefore, you will have to cast the output of the iterate function to the ee.Object it actually should be (you as a user know it should be an image). You can check that using ee.Object.name():

// Check what kind of object it is:
print(landsat5.name()); // ComputedObject
// Cast to an image
landsat5 = ee.Image(landsat5);
print(landsat5.name()); // Image

Link script