Page Summary
-
This tool generates a chart displaying a histogram of band values from a specified region of an image.
-
The chart's X-axis represents histogram buckets of band values, while the Y-axis shows the frequency of pixels within each bucket.
-
The
ui.Chart.image.histogramfunction is used to generate the chart and accepts various optional arguments to customize the histogram computation.
- X-axis: Histogram buckets (of band value).
- Y-axis: Frequency (number of pixels with a band value in the bucket).
Returns a chart.
| Usage | Returns |
|---|---|
ui.Chart.image.histogram(image, region
, scale
, maxBuckets
, minBucketWidth
, maxRaw
, maxPixels
)
|
ui.Chart |
| Argument | Type | Details |
|---|---|---|
image
|
Image | The image to generate a histogram from. |
region
|
Feature|FeatureCollection|Geometry, optional | The region to reduce. If omitted, uses the entire image. |
scale
|
Number, optional | The pixel scale used when applying the histogram reducer, in meters. |
maxBuckets
|
Number, optional | The maximum number of buckets to use when building a histogram; will be rounded up to a power of 2. |
minBucketWidth
|
Number, optional | The minimum histogram bucket width, or null to allow any power of 2. |
maxRaw
|
Number, optional | The number of values to accumulate before building the initial histogram. |
maxPixels
|
Number, optional | If specified, overrides the maximum number of pixels allowed in the histogram reduction. Defaults to 1e6. |
Examples
Code Editor (JavaScript)
// Define a MODIS surface reflectance composite. var modisSr = ee . ImageCollection ( 'MODIS/006/MOD09A1' ) . filter ( ee . Filter . date ( '2018-06-01' , '2018-09-01' )) . select ([ 'sur_refl_b01' , 'sur_refl_b02' , 'sur_refl_b06' ]) . mean (); // Define a region to calculate histogram for. var histRegion = ee . Geometry . Rectangle ([ - 112.60 , 40.60 , - 111.18 , 41.22 ]); // Define the chart and print it to the console. var chart = ui . Chart . image . histogram ({ image : modisSr , region : histRegion , scale : 500 }) . setSeriesNames ([ 'Red' , 'NIR' , 'SWIR' ]) . setOptions ({ title : 'MODIS SR Reflectance Histogram' , hAxis : { title : 'Reflectance (scaled by 1e4)' , titleTextStyle : { italic : false , bold : true }, }, vAxis : { title : 'Count' , titleTextStyle : { italic : false , bold : true }}, colors : [ 'cf513e' , '1d6b99' , 'f0af07' ] }); print ( chart );
