Image Reductions

To reduce an Image, use image.reduce(). Reducing an image functions in an analogous way to imageCollection.reduce(), except the bands of the image are input to the reducer rather than the images in the collection. The output is also an image with number of bands equal to number of reducer outputs. For example:

// Load an image and select some bands of interest.
var image = ee.Image('LANDSAT/LC8_L1T/LC80440342014077LGN00')
    .select(['B4', 'B3', 'B2']);

// Reduce the image to get a one-band maximum value image.
var maxValue = image.reduce(ee.Reducer.max());

// Display the result.
Map.centerObject(image, 10);
Map.addLayer(maxValue, {max: 13000}, 'Maximum value image');


Google Earth Engine API