ui.Chart.image.histogram

AI-generated Key Takeaways

• 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.histogram function is used to generate the chart and accepts various optional arguments to customize the histogram computation.

Generates a Chart from an image. Computes and plots histograms of the values of the bands in the specified region of the image.

  - 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);