ee.Image.updateMask

    Updates an image's mask at all positions where the existing mask is not zero. The output image retains the metadata and footprint of the input image.
    Usage Returns
    Image. updateMask (mask) Image
    Argument Type Details
    this: image
    		Image Input image.
    mask
    		Image New mask for the image, as a floating-point value in the range [0, 1] (invalid = 0, valid = 1). If this image has a single band, it is used for all bands in the input image; otherwise, must have the same number of bands as the input image.

    Examples

    Code Editor (JavaScript) 

     // A Sentinel-2 surface reflectance image. 
 var 
  
 img 
  
 = 
  
 ee 
 . 
 Image 
 ( 
 'COPERNICUS/S2_SR/20210109T185751_20210109T185931_T10SEG' 
 ); 
 var 
  
 trueColorViz 
  
 = 
  
 { 
  
 bands 
 : 
  
 [ 
 'B4' 
 , 
  
 'B3' 
 , 
  
 'B2' 
 ], 
  
 min 
 : 
  
 0 
 , 
  
 max 
 : 
  
 2700 
 , 
  
 gamma 
 : 
  
 1.3 
 }; 
 print 
 ( 
 'Sentinel-2 image' 
 , 
  
 img 
 ); 
 Map 
 . 
 setCenter 
 ( 
 - 
 122.36 
 , 
  
 37.47 
 , 
  
 10 
 ); 
 Map 
 . 
 addLayer 
 ( 
 img 
 , 
  
 trueColorViz 
 , 
  
 'Sentinel-2 image' 
 ); 
 // Create a Boolean land mask from the SWIR1 band; water is value 0, land is 1. 
 var 
  
 landMask 
  
 = 
  
 img 
 . 
 select 
 ( 
 'B11' 
 ). 
 gt 
 ( 
 100 
 ); 
 print 
 ( 
 'Land mask' 
 , 
  
 landMask 
 ); 
 Map 
 . 
 addLayer 
 ( 
 landMask 
 , 
  
 { 
 palette 
 : 
  
 [ 
 'blue' 
 , 
  
 'lightgreen' 
 ]}, 
  
 'Land mask' 
 ); 
 // Apply the single-band land mask to all image bands; pixel values equal to 0 
 // in the mask become invalid in the image. 
 var 
  
 imgMasked 
  
 = 
  
 img 
 . 
 updateMask 
 ( 
 landMask 
 ); 
 print 
 ( 
 'Image, land only' 
 , 
  
 imgMasked 
 ); 
 Map 
 . 
 addLayer 
 ( 
 imgMasked 
 , 
  
 trueColorViz 
 , 
  
 'Image, land only' 
 ); 
 // Masks are band-specific. Here, a multi-band mask image is used to update 
 // corresponding input image band masks. 
 var 
  
 imgBandSubset 
  
 = 
  
 img 
 . 
 select 
 ([ 
 'B4' 
 , 
  
 'B3' 
 , 
  
 'B2' 
 ]); 
 var 
  
 bandSpecificMasks 
  
 = 
  
 imgBandSubset 
 . 
 gt 
 ( 
 200 
 ); 
 var 
  
 imgBandSubsetMasked 
  
 = 
  
 imgBandSubset 
 . 
 updateMask 
 ( 
 bandSpecificMasks 
 ); 
 print 
 ( 
 'Multi-band mask image' 
 , 
  
 bandSpecificMasks 
 ); 
 print 
 ( 
 'Image, variable band masks' 
 , 
  
 imgBandSubsetMasked 
 ); 
 Map 
 . 
 addLayer 
 ( 
 bandSpecificMasks 
 , 
  
 null 
 , 
  
 'Multi-band mask image' 
 ); 
 Map 
 . 
 addLayer 
 ( 
 imgBandSubsetMasked 
 , 
  
 trueColorViz 
 , 
  
 'Image, variable band masks' 
 ); 
 // Note that there is only a single alpha channel for visualization, so when 
 // the ee.Image is rendered as an RGB image or map tiles, a masked pixel in any 
 // band will result in transparency for all bands. 
 // Floating point mask values between 0 and 1 will be used to define opacity 
 // in visualization via Map.addLayer and ee.Image.visualize. 
 var 
  
 landMaskFloat 
  
 = 
  
 landMask 
 . 
 add 
 ( 
 0.65 
 ); 
 var 
  
 imgMaskedFloat 
  
 = 
  
 img 
 . 
 updateMask 
 ( 
 landMaskFloat 
 ); 
 print 
 ( 
 'Image, partially transparent' 
 , 
  
 imgMaskedFloat 
 ); 
 Map 
 . 
 addLayer 
 ( 
 imgMaskedFloat 
 , 
  
 trueColorViz 
 , 
  
 'Image, partially transparent' 
 );

    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) 

     # A Sentinel-2 surface reflectance image. 
 img 
 = 
 ee 
 . 
 Image 
 ( 
 'COPERNICUS/S2_SR/20210109T185751_20210109T185931_T10SEG' 
 ) 
 true_color_viz 
 = 
 { 
 'bands' 
 : 
 [ 
 'B4' 
 , 
 'B3' 
 , 
 'B2' 
 ], 
 'min' 
 : 
 0 
 , 
 'max' 
 : 
 2700 
 , 
 'gamma' 
 : 
 1.3 
 , 
 } 
 display 
 ( 
 'Sentinel-2 image' 
 , 
 img 
 ) 
 m 
 = 
 geemap 
 . 
 Map 
 () 
 m 
 . 
 set_center 
 ( 
 - 
 122.36 
 , 
 37.47 
 , 
 10 
 ) 
 m 
 . 
 add_layer 
 ( 
 img 
 , 
 true_color_viz 
 , 
 'Sentinel-2 image' 
 ) 
 # Create a Boolean land mask from the SWIR1 band water is value 0, land is 1. 
 land_mask 
 = 
 img 
 . 
 select 
 ( 
 'B11' 
 ) 
 . 
 gt 
 ( 
 100 
 ) 
 display 
 ( 
 'Land mask' 
 , 
 land_mask 
 ) 
 m 
 . 
 add_layer 
 ( 
 land_mask 
 , 
 { 
 'palette' 
 : 
 [ 
 'blue' 
 , 
 'lightgreen' 
 ]}, 
 'Land mask' 
 ) 
 # Apply the single-band land mask to all image bands pixel values equal to 0 
 # in the mask become invalid in the image. 
 img_masked 
 = 
 img 
 . 
 updateMask 
 ( 
 land_mask 
 ) 
 display 
 ( 
 'Image, land only' 
 , 
 img_masked 
 ) 
 m 
 . 
 add_layer 
 ( 
 img_masked 
 , 
 true_color_viz 
 , 
 'Image, land only' 
 ) 
 # Masks are band-specific. Here, a multi-band mask image is used to update 
 # corresponding input image band masks. 
 img_band_subset 
 = 
 img 
 . 
 select 
 ([ 
 'B4' 
 , 
 'B3' 
 , 
 'B2' 
 ]) 
 band_specific_masks 
 = 
 img_band_subset 
 . 
 gt 
 ( 
 200 
 ) 
 img_band_subset_masked 
 = 
 img_band_subset 
 . 
 updateMask 
 ( 
 band_specific_masks 
 ) 
 display 
 ( 
 'Multi-band mask image' 
 , 
 band_specific_masks 
 ) 
 display 
 ( 
 'Image, variable band masks' 
 , 
 img_band_subset_masked 
 ) 
 m 
 . 
 add_layer 
 ( 
 band_specific_masks 
 , 
 None 
 , 
 'Multi-band mask image' 
 ) 
 m 
 . 
 add_layer 
 ( 
 img_band_subset_masked 
 , 
 true_color_viz 
 , 
 'Image, variable band masks' 
 ) 
 # Note that there is only a single alpha channel for visualization, so when 
 # the ee.Image is rendered as an RGB image or map tiles, a masked pixel in any 
 # band will result in transparency for all bands. 
 # Floating point mask values between 0 and 1 will be used to define opacity 
 # in visualization via m.add_ee_layer and ee.Image.visualize. 
 land_mask_float 
 = 
 land_mask 
 . 
 add 
 ( 
 0.65 
 ) 
 img_masked_float 
 = 
 img 
 . 
 updateMask 
 ( 
 land_mask_float 
 ) 
 display 
 ( 
 'Image, partially transparent' 
 , 
 img_masked_float 
 ) 
 m 
 . 
 add_layer 
 ( 
 img_masked_float 
 , 
 true_color_viz 
 , 
 'Image, partially transparent' 
 ) 
 m
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