ee.Image.remap

Maps from input values to output values, represented by two parallel lists. Any input values not included in the input list are either set to defaultValue if it is given, or masked if it isn't. Note that inputs containing floating point values might sometimes fail to match due to floating point precision errors.
UsageReturns
Image.remap(from, to, defaultValue, bandName)Image
ArgumentTypeDetails
this: imageImageThe image to which the remapping is applied.
fromListThe source values (numbers or ee.Array). All values in this list will be mapped to the corresponding value in 'to'.
toListThe destination values (numbers or ee.Array). These are used to replace the corresponding values in 'from'. Must have the same number of values as 'from'.
defaultValueObject, default: nullThe default value to replace values that weren't matched by a value in 'from'. If not specified, unmatched values are masked out.
bandNameString, default: nullThe name of the band to remap. If not specified, the first band in the image is used.

Examples

Code Editor (JavaScript)

// A land cover image.
var img = ee.Image('ESA/WorldCover/v100/2020');

// A list of pixel values to replace.
var fromList = [10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 100];

// A corresponding list of replacement values (10 becomes 1, 20 becomes 2, etc).
var toList =   [ 1,  2,  2,  2,  3,  2,  4,  5,  6,  6,  2];

// Replace pixel values in the image. If the image is multi-band, only the
// remapped band will be returned. The returned band name is "remapped".
// Input image properties are retained in the output image.
var imgRemap = img.remap({
  from: fromList,
  to: toList,
  defaultValue: 0,
  bandName: 'Map'
});

// Display the original and remapped images. Note that similar land cover
// classes in the original image are grouped into aggregate classes by
// from → to value mapping.
Map.addLayer(img, null, 'Original image');
Map.addLayer(imgRemap, {
    min: 1, max: 6,
    palette:'darkgreen, lightgreen, red, white, blue, lightblue'
  }, 'Remapped image');