ee.Image.gt

  • The gt() function compares corresponding bands of two images, returning 1 if the first image's band value is greater than the second image's band value, and 0 otherwise.

  • If the images have different numbers of bands, single-band images are compared against all bands of the multi-band image; if they have the same number of bands but different names, bands are compared in their natural order.

  • The output is a boolean image with bands named according to the longer input image or, if equal in length, the first image's band names.

  • This function is useful for creating binary masks based on thresholding, such as identifying areas above sea level in an elevation dataset.

 Returns 1 if and only if the first value is greater than the second for each matched pair of bands in image1 and image2. If either image1 or image2 has only 1 band, then it is used against all the bands in the other image. If the images have the same number of bands, but not the same names, they're used pairwise in the natural order. The output bands are named for the longer of the two inputs, or if they're equal in length, in image1's order. The type of the output pixels is boolean.

UsageReturns
Image.gt(image2)Image
ArgumentTypeDetails
this: image1ImageThe image from which the left operand bands are taken.
image2ImageThe image from which the right operand bands are taken.

Examples

Code Editor (JavaScript)

// Show world oceans in blue and anything higher than the ellipsoid as gray.
// The bedrock layer is generally close to the geoid (sealevel).
var elevation = ee.Image('NOAA/NGDC/ETOPO1').select('bedrock');
var waterLand = elevation.gt(0.0);
var waterLandViz = {palette: ['cadetblue', 'lightgray']};
Map.addLayer(waterLand, waterLandViz, 'water_land');

Python setup

See the Python Environment page for information on the Python API and using geemap for interactive development.

import ee
import geemap.core as geemap

Colab (Python)

# Show world oceans in blue and anything higher than the ellipsoid as gray.
# The bedrock layer is generally close to the geoid (sealevel).
elevation = ee.Image('NOAA/NGDC/ETOPO1').select('bedrock')
water_land = elevation.gt(0.0)
water_land_viz = {'palette': ['cadetblue', 'lightgray']}
m = geemap.Map()
m.add_layer(water_land, water_land_viz, 'water_land')
m