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GDAL-RASTER-OVERVIEW-ADD(1)	     GDAL	   GDAL-RASTER-OVERVIEW-ADD(1)

NAME
       gdal-raster-overview-add	- Add overviews	to a raster dataset

       Added in	version	3.11.

SYNOPSIS
	  Usage: gdal raster overview add [OPTIONS] <DATASET>

	  Adding overviews.

	  Positional arguments:
	    --dataset <DATASET>		       Dataset (to be updated in-place,	unless --external) [required]

	  Common Options:
	    -h,	--help			       Display help message and	exit
	    --json-usage		       Display usage as	JSON document and exit
	    --config <KEY>=<VALUE>	       Configuration option [may be repeated]
	    --progress			       Display progress	bar

	  Options:
	    --external			       Add external overviews
	    -r,	--resampling <RESAMPLING>      Resampling method. RESAMPLING=nearest|average|cubic|cubicspline|lanczos|bilinear|gauss|average_magphase|rms|mode
	    --levels <LEVELS>		       Levels /	decimation factors [may	be repeated]
	    --min-size <MIN-SIZE>	       Maximum width or	height of the smallest overview	level.

	  Advanced Options:
	    --oo, --open-option	<KEY>=<VALUE>  Open options [may be repeated]

DESCRIPTION
       gdal  raster  overview add can be used to build or rebuild overview im-
       ages for	most supported file formats with one of	 several  downsampling
       algorithms.

       --dataset <DATASET>
	      Dataset	name,  to  be  updated	in-place  by  default  (unless
	      --external is specified).	Required.

       --external
	      Create external .ovr overviews as	GeoTIFF	files.

       --resampling {nearest|average|cubic|cubicspline|lanczos|bilin-
       ear|gauss|average_magphase|rms|mode}
	      Select a resampling algorithm. The default is nearest, which  is
	      generally	not appropriate	if sub-pixel accuracy is desired.

	      When  refreshing	existing  TIFF	overviews, the previously used
	      method,  as  noted  in  the  RESAMPLING  metadata	 item  of  the
	      overview,	will be	used if	-r is not specified.

	      The available methods are:

	      nearest applies a	nearest	neighbour (simple sampling) resampler.

	      average computes the average of all non-NODATA contributing pix-
	      els. This	is a weighted average taking into account properly the
	      weight  of  source  pixels  not contributing fully to the	target
	      pixel.

	      bilinear applies a bilinear convolution kernel.

	      cubic applies a cubic convolution	kernel.

	      cubicspline applies a B-Spline convolution kernel.

	      lanczos applies a	Lanczos	windowed sinc convolution kernel.

	      gauss applies a Gaussian kernel before computing	the  overview,
	      which  can  lead	to better results than simple averaging	in e.g
	      case of sharp edges with high contrast or	 noisy	patterns.  The
	      advised  level  values should be 2, 4, 8,	...  so	that a 3x3 re-
	      sampling Gaussian	kernel is selected.

	      average_magphase averages	complex	data in	mag/phase space.

	      rms computes the root mean  squared  /  quadratic	 mean  of  all
	      non-NODATA contributing pixels

	      mode  selects the	value which appears most often of all the sam-
	      pled points.

       --levels	<level1,level2,...>
	      A	list of	overview levels	to build. Each overview	level must  be
	      an integer value greater or equal	to 2.

	      When explicit levels are not specified,

	      •	If  there  are	already	 existing overviews, the corresponding
		levels will be used to refresh them if no explicit levels  are
		specified.

	      •	Otherwise,  appropriate	 overview power-of-two factors will be
		selected until the smallest overview is	smaller	than the value
		of the --min-size switch.

       --min-size <val>
	      Maximum width or height of the  smallest	overview  level.  Only
	      taken  into  account  if	explicit levels	are not	specified. De-
	      faults to	256.

EXAMPLES
   Example 1: Create overviews,	embedded in the	supplied TIFF file, with auto-
       matic computation of levels
	  gdal raster overview add -r average abc.tif

   Example 2: Create overviews,	embedded in the	supplied TIFF file
	  gdal raster overview add -r average --levels=2,4,8,16	abc.tif

   Example 3: Create an	external compressed GeoTIFF overview file from the ER-
       DAS .IMG	file
	  gdal raster overview add --external --levels=2,4,8,16	--config COMPRESS_OVERVIEW=DEFLATE erdas.img

   Example 4: Create an	external JPEG-compressed GeoTIFF overview file from  a
       3-band RGB dataset
       If  the	dataset	 is  a	writable  GeoTIFF,  you	 also  need to add the
       --external option to force the generation of external overview.

	  gdal raster overview add --config COMPRESS_OVERVIEW=JPEG --config PHOTOMETRIC_OVERVIEW=YCBCR
		   --config INTERLEAVE_OVERVIEW=PIXEL rgb_dataset.ext 2	4 8 16

   Example 5: Create overviews for a specific subdataset
       For example, one	of potentially many raster layers in a GeoPackage (the
       "filename" parameter must be driver  prefix,  filename  and  subdataset
       name, like e.g. shown by	gdalinfo):

	  gdal raster overview add GPKG:file.gpkg:layer

AUTHOR
       Even Rouault <even.rouault@spatialys.com>

COPYRIGHT
       1998-2025

				 Jul 12, 2025	   GDAL-RASTER-OVERVIEW-ADD(1)

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