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ee.ImageCollection.max
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Reduces an image collection by calculating the maximum value of each pixel across the stack of all matching bands. Bands are matched by name.
Usage Returns ImageCollection. max ()
Image
Argument Type Details this: collection
ImageCollection The image collection to reduce.
Examples
Code Editor (JavaScript)
// Sentinel-2 image collection for July 2021 intersecting a point of interest.
// Reflectance, cloud probability, and scene classification bands are selected.
var col = ee . ImageCollection ( 'COPERNICUS/S2_SR' )
. filterDate ( '2021-07-01' , '2021-08-01' )
. filterBounds ( ee . Geometry . Point ( - 122.373 , 37.448 ))
. select ( 'B.*|MSK_CLDPRB|SCL' );
// Visualization parameters for reflectance RGB.
var visRefl = {
bands : [ 'B11' , 'B8' , 'B3' ],
min : 0 ,
max : 4000
};
Map . setCenter ( - 122.373 , 37.448 , 9 );
Map . addLayer ( col , visRefl , 'Collection reference' , false );
// Reduce the collection to a single image using a variety of methods.
var mean = col . mean ();
Map . addLayer ( mean , visRefl , 'Mean (B11, B8, B3)' );
var median = col . median ();
Map . addLayer ( median , visRefl , 'Median (B11, B8, B3)' );
var min = col . min ();
Map . addLayer ( min , visRefl , 'Min (B11, B8, B3)' );
var max = col . max ();
Map . addLayer ( max , visRefl , 'Max (B11, B8, B3)' );
var sum = col . sum ();
Map . addLayer ( sum ,
{ bands : [ 'MSK_CLDPRB' ], min : 0 , max : 500 }, 'Sum (MSK_CLDPRB)' );
var product = col . product ();
Map . addLayer ( product ,
{ bands : [ 'MSK_CLDPRB' ], min : 0 , max : 1e10 }, 'Product (MSK_CLDPRB)' );
// ee.ImageCollection.mode returns the most common value. If multiple mode
// values occur, the minimum mode value is returned.
var mode = col . mode ();
Map . addLayer ( mode , { bands : [ 'SCL' ], min : 1 , max : 11 }, 'Mode (pixel class)' );
// ee.ImageCollection.count returns the frequency of valid observations. Here,
// image pixels are masked based on cloud probability to add valid observation
// variability to the collection. Note that pixels with no valid observations
// are masked out of the returned image.
var notCloudCol = col . map ( function ( img ) {
return img . updateMask ( img . select ( 'MSK_CLDPRB' ). lte ( 10 ));
});
var count = notCloudCol . count ();
Map . addLayer ( count , { min : 1 , max : 5 }, 'Count (not cloud observations)' );
// ee.ImageCollection.mosaic composites images according to their position in
// the collection (priority is last to first) and pixel mask status, where
// invalid (mask value 0) pixels are filled by preceding valid (mask value >0)
// pixels.
var mosaic = notCloudCol . mosaic ();
Map . addLayer ( mosaic , visRefl , 'Mosaic (B11, B8, B3)' );
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)
# Sentinel-2 image collection for July 2021 intersecting a point of interest.
# Reflectance, cloud probability, and scene classification bands are selected.
col = (
ee . ImageCollection ( 'COPERNICUS/S2_SR' )
. filterDate ( '2021-07-01' , '2021-08-01' )
. filterBounds ( ee . Geometry . Point ( - 122.373 , 37.448 ))
. select ( 'B.*|MSK_CLDPRB|SCL' )
)
# Visualization parameters for reflectance RGB.
vis_refl = { 'bands' : [ 'B11' , 'B8' , 'B3' ], 'min' : 0 , 'max' : 4000 }
m = geemap . Map ()
m . set_center ( - 122.373 , 37.448 , 9 )
m . add_layer ( col , vis_refl , 'Collection reference' , False )
# Reduce the collection to a single image using a variety of methods.
mean = col . mean ()
m . add_layer ( mean , vis_refl , 'Mean (B11, B8, B3)' )
median = col . median ()
m . add_layer ( median , vis_refl , 'Median (B11, B8, B3)' )
min = col . min ()
m . add_layer ( min , vis_refl , 'Min (B11, B8, B3)' )
max = col . max ()
m . add_layer ( max , vis_refl , 'Max (B11, B8, B3)' )
sum = col . sum ()
m . add_layer (
sum , { 'bands' : [ 'MSK_CLDPRB' ], 'min' : 0 , 'max' : 500 }, 'Sum (MSK_CLDPRB)'
)
product = col . product ()
m . add_layer (
product ,
{ 'bands' : [ 'MSK_CLDPRB' ], 'min' : 0 , 'max' : 1e10 },
'Product (MSK_CLDPRB)' ,
)
# ee.ImageCollection.mode returns the most common value. If multiple mode
# values occur, the minimum mode value is returned.
mode = col . mode ()
m . add_layer (
mode , { 'bands' : [ 'SCL' ], 'min' : 1 , 'max' : 11 }, 'Mode (pixel class)'
)
# ee.ImageCollection.count returns the frequency of valid observations. Here,
# image pixels are masked based on cloud probability to add valid observation
# variability to the collection. Note that pixels with no valid observations
# are masked out of the returned image.
not_cloud_col = col . map (
lambda img : img . updateMask ( img . select ( 'MSK_CLDPRB' ) . lte ( 10 ))
)
count = not_cloud_col . count ()
m . add_layer ( count , { 'min' : 1 , 'max' : 5 }, 'Count (not cloud observations)' )
# ee.ImageCollection.mosaic composites images according to their position in
# the collection (priority is last to first) and pixel mask status, where
# invalid (mask value 0) pixels are filled by preceding valid (mask value >0)
# pixels.
mosaic = not_cloud_col . mosaic ()
m . add_layer ( mosaic , vis_refl , 'Mosaic (B11, B8, B3)' )
m
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Last updated 2023-10-06 UTC.
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[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2023-10-06 UTC."],[[["`ImageCollection.max()` reduces an image collection to a single image by calculating the maximum pixel value across all images in the collection for each band."],["Bands with matching names are compared pixel-wise to determine the maximum value."],["The result is a single image containing the maximum values for each band across the collection."],["This method is useful for creating composite images or identifying the highest values in a time series."]]],[]]