google earth engine - Any way to have variable min and max in one visualization parameter?

What I mean is: I'm using the "3 standard deviations" value to visualize my data, but this changes seasonally so I need to update what the values actually are for each image. Can I create a "3 standard deviations" palette that will automatically calculate these new values for each image?

In pseudocode terms, I'm imagining something along these lines:

var Oa04_palette = {

bands: ['Oa04_radiance'],
min: sminus3,
max: splus3,
sminus3: standard deviation of 'Oa04_radiance' * -3,
splus3: standard deviation of 'Oa04_radiance' * 3
};

So when I add a bunch of layers all using this palette, it will always use the appropriate min-max range for that layer.

Answer

As I understand correctly, you want to add layers to the map using min and max values based on mean-stdDev*3 and mean+stdDev*3?

There could be several ways achieving that, but here is a simple example:

First, make a random geometry and image:

  var scale = Map.getScale();
  var geometry = Map.getCenter().buffer(scale*10);
  var randomImage = ee.Image.random().multiply(scale); 

Then, we calculate the mean and stdDev value of that image in the specified region:

  var meanStdDev = randomImage.reduceRegion(
              ee.Reducer.mean().combine(ee.Reducer.stdDev(), null, true), geometry, scale);
  meanStdDev = meanStdDev.rename(meanStdDev.keys(), ['mean','stdDev']);  

We then need to evaluate the outcomes to the client side, as the Map visible parameters require client-side input:

  meanStdDev.evaluate(function(val){
    var mean = val.mean;
    var stdDev = val.stdDev;
  var visParam = {
          min: mean - (stdDev * 3),
          max: mean + (stdDev * 3),
          };

Then we add the layer to the map using the visParams defined:

Map.addLayer(randomImage, visParam); 

As an example, here is a simple app that changes the visible parameters as you zoom in/out: Link code