# How to Use the Arithmetic Module

This series of video tutorials introduces the Arithmetic module and examples of use cases.

**1. Introduction**

This first video introduces the Arithmetic module and most of its parameters.

It also provides a simple example of usage, applying the expression A*(x>.01) to mask a portion of an image.

**2. Some basics of the Arithmetic module**

This tutorial demonstrates a basic application of the Arithmetic module. Pixels of intensity values less than 900 are filtered out of a greyscale image using the simple expression (A>900)*A.

**3. Combine labels**

This tutorial demonstrates how to use the Arithmetic module to combine binary fields into a label field with several labels, remove a label from a label field, or change the label id of a specific label in a label field.

The binary data used as the input of this tutorial have been obtained by segmenting bones, as explained in those two Xtras:

- How to segment cavities using the Compute Ambient Occlusion module
- How to perform trabecular and cortical bone segmentation

This short video demonstrates two examples of **common mistakes made when using the Arithmetic module on label fields**. It
explains the mistakes and shows how to correct them.

**4. Masking operations**

This tutorial explains how to use the Arithmetic module for masking operations. It compares the Mask module and the
Arithmetic module. Although they are interchangeable for masking with binary images, only the Arithmetic module
allows masking with specific label(s) of a label field.

**Additional resource:** how to use the Arithmetic module to divide a full data volume into defined sub-volume blocks before performing a Label Analysis.