Filter (Spatial Analyst)

Summary

Performs either a smoothing (Low pass) or edge-enhancing (High pass) filter on a raster.

Learn more about how Filter works

Usage

• The LOW filter option is an averaging (smoothing) filter. The HIGH filter option is an edge-enhancement filter.

• Input NoData cells may receive a value in the output if the Ignore NoData in calculations option is checked, provided at least one cell within the filter neighborhood has a valid value.

• You can use the Focal Statistics tool to create custom filters to your specification.

Syntax

Filter (in_raster, {filter_type}, {ignore_nodata})

Parameter	Explanation	Data Type
in_raster	The input raster on which to perform the filter operation.	Raster Layer
filter_type (Optional)	The type of filter operation to perform. LOW — Traverses a low pass 3-by-3 filter over the raster. This option smooths the entire input raster and reduces the significance of anomalous cells.This is the default option. HIGH — Traverses a high pass 3-by-3 filter over the raster. This option enhances the edges of subdued features in a raster.	String
ignore_nodata (Optional)	Denotes whether NoData values are ignored by the filter calculation. DATA — If a NoData value exists within the filter, the NoData value will be ignored. Only cells within the filter that have data values will be used in determining the output. NODATA — If a NoData value exists within the filter, the output for the processing cell will be NoData. With this option, the presence of a NoData value implies that there is insufficient information to determine the statistic value for the neighborhood.	Boolean

Return Value

Name	Explanation	Data Type
out_raster	The output filtered raster.	Raster

Code Sample

Filter example 1 (Python window)

This example applies a high-pass filter to the input raster.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
filterOut =  Filter("elevation", "HIGH", "DATA") 
filterOut.save("C:/sapyexamples/output/filtered")

Filter example 2 (stand-alone script)

This example applies a low-pass filter to the input raster.

# Name: Filter_Ex_02.py
# Description: Performs a preset focal filter on a raster. 
# Requirements: Spatial Analyst Extension
# Author: ESRI

# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *

# Set environment settings
env.workspace = "C:/sapyexamples/data"

# Set local variables
inRaster = "elevation" 

# Check out the ArcGIS Spatial Analyst extension license
arcpy.CheckOutExtension("Spatial")

# Execute Filter
filterOut =  Filter(inRaster, "LOW", "") 

# Save the output 
filterOut.save("C:/sapyexamples/output/filterout")

Environments

Cell Size, Current Workspace, Mask, Output Coordinate System, Extent, Scratch Workspace, Snap Raster

Licensing Information

ArcView: Requires Spatial Analyst

ArcEditor: Requires Spatial Analyst

ArcInfo: Requires Spatial Analyst