ee_extra.Spectral.core.matchHistogram#

ee_extra.Spectral.core.matchHistogram(source, target, bands=None, geometry=None, maxBuckets=256)[source]#

Adjust the histogram of an image to match a target image.

Parameters:

  • source (Image) – Image to adjust.

  • target (Image) – Image to use as the histogram reference.

  • bands (Optional[Dict[str, str]]) – An optional dictionary of band names to match, with source bands as keys and target bands as values. If none is provided, bands will be matched by name. Any bands not included here will be dropped.

  • geometry (Optional[Geometry]) – The optional region to match histograms in that overlaps both images. If none is provided, the geometry of the source image will be used. If the source image is unbounded and no geometry is provided, histogram matching will fail.

  • maxBuckets (int) – The maximum number of buckets to use when building histograms. More buckets will require more memory and time but will generate more accurate results. The number of buckets will be rounded to the nearest power of 2.

Return type:

Image

Returns:

The adjusted image containing the matched source bands.

Examples

>>> import ee
>>> from ee_extra.Spectral.core import matchHistogram
>>> ee.Initialize()

The matchHistogram function can easily be used to match histograms of two images from the same collection taken on different days. For example, we can match two NAIP orthophotos.

>>> source = ee.Image("USDA/NAIP/DOQQ/m_4512135_se_10_1_20110804")
>>> target = ee.Image("USDA/NAIP/DOQQ/m_4512135_se_10_1_20140905")
>>> matched = matchHistogram(source, target)

When the images have identical band names, matchHistogram will apply band-wise matching. When images don’t have identical band names, you can provide a dictionary to map the source bands to the target bands. For example, this can be used to match scenes from Landsat 8 and Landsat 7.

>>> source = ee.Image("LANDSAT/LC08/C01/T1_TOA/LC08_047027_20160819")
>>> target = ee.Image("LANDSAT/LE07/C01/T1_TOA/LE07_046027_20150701")
>>> bands = {
>>>    "B4": "B3",
>>>    "B3": "B2",
>>>    "B2": "B1"
>>> }
>>> matched = matchHistogram(source, target, bands=bands)