Low-Pass Filter

This workflow demonstrates a low-pass filter with configurable radius, exposed as a KNIME node and executed on ImageJ’s lymp.tif sample image. The filter utilizes forward and inverse fast Fourier transforms, available as part of the ImageJ Ops library but not yet (as of this writing) wrapped as built-in KNIME Image Processing nodes.

The “Low-pass Filter…” node is a wrapped ImageJ command from the ImageJ tutorials. To add it to your KNIME Analytics Platform installation, perform the following steps:

1. Download the low-pass-filter JAR file via the following link:

https://maven.scijava.org/service/local/artifact/maven/redirect?r=snapshots&g=imagej-tutorials&a=low-pass-filter&v=1.0.0-SNAPSHOT&e=jar

2. In KNIME Analytics Platform, open the File › Preferences dialog and navigate to KNIME › Image Processing Plugin › ImageJ2 Plugin Installation tab. Click the “add” button and select the file …/tutorials/maven-projects/low-pass-filter/target/low-pass-filter-1.0.0.SNAPSHOT.jar built in the previous step.

3. Restart KNIME Analytics Platform.

4. In the Node Repository, find the node in Community Nodes › KNIME Image Processing > ImageJ2 > Tutorials > Low-pass Filter…

Once these steps are performed, this workflow will be able to execute successfully.

Developers wishing to build the low-pass-filter JAR file themselves may do so as follows:

1. With Git, clone the ImageJ tutorials repository (https://github.com/imagej/tutorials).

2. With Maven, build the maven-projects/low-pass-filter project. (“mvn install” on the command line.)

External resources

• low-pass-filter JAR file
• KNIME Image Processing - ImageJ Extension
• ImageJ Tutorials