NAME

       gdaladdo - gdaladdo builds or rebuilds overview images

SYNOPSIS

       gdaladdo [-r {nearest,average,gauss,cubic,average_mp,average_magphase,mode}]
                [-b band]
                [-ro] [-clean] [--help-general] filename levels

DESCRIPTION

       The gdaladdo utility can be used to build or rebuild overview images for most supported file formats with
       one of several downsampling algorithms.

       -r {nearest (default),average,gauss,cubic,average_mp,average_magphase,mode}:
           Select a resampling algorithm.

       -b band:
           (available  from  GDAL 1.10) Select an input band band for overview generation. Band numbering starts
           from 1. Multiple -b switches may be used to select a set of input bands to generate overviews.

       -ro:
           (available from GDAL 1.6.0) open the dataset  in  read-only  mode,  in  order  to  generate  external
           overview (for GeoTIFF especially).

       -clean:
           (available from GDAL 1.7.0) remove all overviews.

       filename:
           The file to build overviews for (or whose overviews must be removed).

       levels:
           A list of integral overview levels to build. Ignored with -clean option.

       Mode  (available  from  GDAL 1.6.0) selects the value which appears most often of all the sampled points.
       average_mp is unsuitable for use. Average_magphase averages complex data in mag/phase space. Nearest  and
       average  are  applicable  to  normal  image  data.  Nearest applies a nearest neighbour (simple sampling)
       resampler, while average computes the average of all non-NODATA  contributing  pixels.  Cubic  resampling
       (available  from  GDAL  1.7.0)  applies  a  4x4  approximate  cubic  convolution kernel. Gauss resampling
       (available from GDAL 1.6.0) 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 resampling Gaussian kernel is selected.

       gdaladdo  will  honour  properly NODATA_VALUES tuples (special dataset metadata) so that only a given RGB
       triplet (in case of a RGB image) will be considered as the nodata value and not each value of the triplet
       independently per band.

       Selecting a level value like 2 causes an overview level that is 1/2 the resolution (in each dimension) of
       the base layer to be computed. If the file has existing overview levels at a level selected, those levels
       will be recomputed and rewritten in place.

       For internal GeoTIFF overviews (or external overviews in GeoTIFF  format),  note  that  -clean  does  not
       shrink  the file. A later run of gdaladdo with overview levels will cause the file to be expanded, rather
       than reusing the space of the previously deleted overviews. If you just want  to  change  the  resampling
       method on a file that already has overviews computed, you don't need to clean the existing overviews.

       Some  format  drivers do not support overviews at all. Many format drivers store overviews in a secondary
       file with the extension .ovr that is actually in TIFF format.  By  default,  the  GeoTIFF  driver  stores
       overviews internally to the file operated on (if it is writeable), unless the -ro flag is specified.

       Most  drivers  also  support an alternate overview format using Erdas Imagine format. To trigger this use
       the USE_RRD=YES configuration option. This will place the overviews in an associated .aux  file  suitable
       for direct use with Imagine or ArcGIS as well as GDAL applications. (eg --config USE_RRD YES)

External overviews in GeoTIFF format

       External  overviews  created  in  TIFF format may be compressed using the COMPRESS_OVERVIEW configuration
       option. All compression methods, supported by the  GeoTIFF  driver,  are  available  here.  (eg  --config
       COMPRESS_OVERVIEW  DEFLATE). The photometric interpretation can be set with --config PHOTOMETRIC_OVERVIEW
       {RGB,YCBCR,...}, and the interleaving with --config INTERLEAVE_OVERVIEW {PIXEL|BAND}.

       For JPEG compressed external overviews, the JPEG quality can be set with '--config  JPEG_QUALITY_OVERVIEW
       value' (GDAL 1.7.0 or later).

       For  LZW  or  DEFLATE  compressed  external  overviews,  the  predictor  value  can be set with '--config
       PREDICTOR_OVERVIEW 1|2|3' (GDAL 1.8.0 or later).

       To produce the smallest possible JPEG-In-TIFF overviews, you should use :

       --config COMPRESS_OVERVIEW JPEG --config PHOTOMETRIC_OVERVIEW YCBCR --config INTERLEAVE_OVERVIEW PIXEL

       Starting with GDAL 1.7.0, external  overviews  can  be  created  in  the  BigTIFF  format  by  using  the
       BIGTIFF_OVERVIEW  configuration  option  :  --config  BIGTIFF_OVERVIEW  {IF_NEEDED|IF_SAFER|YES|NO}.  The
       default value is IF_NEEDED. The behaviour of this option is exactly the  same  as  the  BIGTIFF  creation
       option documented in the GeoTIFF driver documentation.

       • YES forces BigTIFF.
       • NO forces classic TIFF.
       • IF_NEEDED  will  only create a BigTIFF if it is clearly needed (uncompressed, and overviews larger than
         4GB).
       • IF_SAFER will create BigTIFF if the resulting file might exceed 4GB.
       See the documentation of the GeoTIFF driver for further explanations on all those options.

EXAMPLE

       Create overviews, embedded in the supplied TIFF file:
       gdaladdo -r average abc.tif 2 4 8 16
       Create an external compressed GeoTIFF overview file from the ERDAS .IMG file:
       gdaladdo -ro --config COMPRESS_OVERVIEW DEFLATE erdas.img 2 4 8 16
       Create an external JPEG-compressed GeoTIFF overview file from a 3-band RGB dataset (if the dataset  is  a
       writeable GeoTIFF, you also need to add the -ro option to force the generation of external overview):
       gdaladdo --config COMPRESS_OVERVIEW JPEG --config PHOTOMETRIC_OVERVIEW YCBCR
                --config INTERLEAVE_OVERVIEW PIXEL rgb_dataset.ext 2 4 8 16
       Create an Erdas Imagine format overviews for the indicated JPEG file:
       gdaladdo --config USE_RRD YES airphoto.jpg 3 9 27 81

AUTHORS

       Frank Warmerdam warmerdam@pobox.com, Silke Reimer silke@intevation.de

GDAL                                             Tue Apr 5 2016                                      gdaladdo(1)