# gdal_calc.py

Command line raster calculator with numpy syntax.

## Synopsis

    gdal_calc.py --calc=expression --outfile=out_filename [-A filename]
                 [--A_band=n] [-B...-Z filename] [other_options]

DESCRIPTION

Command line raster calculator with numpy syntax. Use any basic arithmetic supported by numpy arrays such as `+`, `-`, `*`, and `\` along with logical operators such as `>`. Note that all files must have the same dimensions (unless extent option is used), but no projection checking is performed (unless projectionCheck option is used).

--help

  Show this help message and exit

-h

  The same as `--help`.

--calc=expression

  Calculation in numpy syntax using `+`, `-`, `/`, `*`, or any numpy array functions (i.e. `log10()`). Multiple `--calc` options can be listed to produce a multiband file (GDAL >= 3.2).

-A <filename>

  Input gdal raster file, you can use any letter (a-z, A-Z). (lower case supported since GDAL 3.3)

  A letter may be repeated (GDAL >= 3.3). The effect will be to create a 3-dim numpy array. In such a case, the calculation formula must use this input as a 3-dim array and must return a 2D array (see examples below). In case the calculation does not return a 2D array an error would be generated.

--A_band=<n>

  Number of raster band for file A (default 1).

--outfile=<filename>

  Output file to generate or fill.

--NoDataValue=<value>

  Output NoDataValue (default datatype specific value). To indicate not setting a NoDataValue use –NoDataValue=none (GDAL >= 3.3)

  Note

  Using the Python API: `None` value will indicate default datatype specific value. `'none'` value will indicate not setting a NoDataValue.

--hideNoData

  New in version 3.3.

  Ignores the input bands NoDataValue. By default, the input bands NoDataValue are not participating in the calculation. By setting this setting - no special treatment will be performed on the input NoDataValue. and they will be participating in the calculation as any other value. The output will not have a set NoDataValue, unless you explicitly specified a specific value by setting –NoDataValue=<value>.

--type=<datatype>

  Output datatype, must be one of [`Int32`, `Int16`, `Float64`, `UInt16`, `Byte`, `UInt32`, `Float32`].

  Note

  Despite the datatype set using `--type`, when doing intermediate aritmethic operations using operands of the same type, the operation result will honor the original datatype. This may lead into unexpected results in the final result.

--format=<gdal_format>

  GDAL format for output file.

color-table=<filename>

  Allows specifying a filename of a color table (or a ColorTable object) (with Palette Index interpretation) to be used for the output raster. Supported formats: txt (i.e. like gdaldem, but color names are not supported), qlr, qml (i.e. exported from QGIS)

--extent=<option>

  New in version 3.3.

  this option determines how to handle rasters with different extents. this option is mutually exclusive with the projwin option, which is used for providing a custom extent. for all the options below the pixel size (resolution) and SRS (Spatial Reference System) of all the input rasters must be the same. `ignore` (default) - only the dimensions of the rasters are compared. if the dimensions do not agree the operation will fail. `fail` - the dimensions and the extent (bounds) of the rasters must agree, otherwise the operation will fail. `union` - the extent (bounds) of the output will be the minimal rectangle that contains all the input extents. `intersect` - the extent (bounds) of the output will be the maximal rectangle that is contained in all the input extents.

--projwin <ulx> <uly> <lrx> <lry>

  New in version 3.3.

  this option provides a custom extent for the output, it is mutually exclusive with the extent option.

--projectionCheck

  New in version 3.3.

  By default, no projection checking will be performed. By setting this option, if the projection is not the same for all bands then the operation will fail.

--creation-option=<option>

  Passes a creation option to the output format driver. Multiple options may be listed. See format specific documentation for legal creation options for each format.

--co=<option>

  The same as creation-option.

--allBands=[a-z, A-Z]

  Process all bands of given raster (a-z, A-Z). Requires a single calc for all bands.

--overwrite

  Overwrite output file if it already exists.

--debug

  Print debugging information.

--quiet

  Suppress progress messages.

## Python options

New in version 3.3.

The following options are available by using function the python interface of gdal_calc. They are not available using the command prompt.

user_namespace

  A dictionary of custom functions or other names to be available for use in the Calc expression.

return_ds

  If enabled, the output dataset would be returned from the function and not closed.

color_table

  Allows specifying a ColorTable object (with Palette Index interpretation) to be used for the output raster.

## Example

Add two files together:

    gdal_calc.py -A input1.tif -B input2.tif --outfile=result.tif --calc="A+B"

Average of two layers:

    gdal_calc.py -A input1.tif -B input2.tif --outfile=result.tif --calc="(A+B)/2"

Note

In the previous example, beware that if A and B inputs are of the same datatype, for example integers, you may need to force the conversion of one of the operands before the division operation.

    gdal_calc.py -A input.tif -B input2.tif --outfile=result.tif --calc="(A.astype(numpy.float64) + B) / 2"

Add three files together (two options with the same result):

    gdal_calc.py -A input1.tif -B input2.tif -C input3.tif --outfile=result.tif --calc="A+B+C"

New in version 3.3.

    gdal_calc.py -A input1.tif -A input2.tif -A input3.tif --outfile=result.tif --calc="numpy.sum(A,axis=0)".

Average of three layers (two options with the same result):

    gdal_calc.py -A input1.tif -B input2.tif -C input3.tif --outfile=result.tif --calc="(A+B+C)/3"

New in version 3.3.

    gdal_calc.py -A input1.tif -A input2.tif -A input3.tif --outfile=result.tif --calc="numpy.average(a,axis=0)".

Maximum of three layers (two options with the same result):

    gdal_calc.py -A input1.tif -B input2.tif -C input3.tif --outfile=result.tif --calc="numpy.max((A,B,C),axis=0)"

New in version 3.3.

    gdal_calc.py -A input1.tif -A input2.tif -A input3.tif --outfile=result.tif --calc="numpy.max(A,axis=0)"

Set values of zero and below to null:

    gdal_calc.py -A input.tif --outfile=result.tif --calc="A*(A>0)" --NoDataValue=0

Using logical operator to keep a range of values from input:

    gdal_calc.py -A input.tif --outfile=result.tif --calc="A*logical_and(A>100,A<150)"

Work with multiple bands:

    gdal_calc.py -A input.tif --A_band=1 -B input.tif --B_band=2 --outfile=result.tif --calc="(A+B)/2" --calc="B*logical_and(A>100,A<150)"