When processing your images and building up your cutting-edge processing chain with OTB, the need arises to do simple arithmetic operations between the different bands of your images : substracting two bands to study the image differences, threshold the image, apply conditional filtering rule or perform a logarithmic rescaling for example. It requires the use of several basic operation filters, such as itk::SubtractImageFilter, for each and every operand you want to apply. The brand new BandMathImageFilter provides a simpler and more efficient way to perform complex mathematical operations over n images. It is based on the mathematical parser library muParser and comes with a bunch of build-in functions and operators (listed here). This homebrewed digital calculator is also bundled with custom functions allowing to compute a full expression result simply and really fast, since the filter supports streaming and multi-threading.

This new functionality has also been included into the Monteverdi application to provide a intuitive way to perform complex band computation the easy way. The module also prevents error in the mathematical command by checking the expression as the user types it, and notifying information on the detected error:

The new Monteverdi Band Math module showing syntax error on mathematical expression.

Correct mathematical expressions are highlighted in green.

This feature is already available in the release 3.6 of the Orfeo Toolbox.

Give it a try!