The Grouped Z Project tool (" Image/Stacks/Tools/Grouped Z Project.") works similarly to Z Project in terms of projection methods. The six projection methods clockwise from top left: average intensity, maximum intensity, minimum intensity, median, standard deviation, and sum slices. These remaining methods also have their distinguishing characteristics, as seen by the median projection which gives the clearest rendering with the trade-off of less of filtering out more of the image in the projection. In the case of the MRI stack, maximum intensity is a preferable method to view the external head rendering while other methods of projection may be used to examine the internal brain components. As seen below, by applying a z transform to an MRI stack using different projection methods, the results can be very different. The appropriate projection type will vary depending on the type of data being represented.
![imagej macro function imagej macro function](https://biii.eu/sites/default/files/styles/large/public/2018-05/adipo_baecker.png)
There are six different projection types to choose from: average intensity, maximum intensity, minimum intensity, sum slices, standard deviation, and median. The default for these values is the endpoint slices of the stack. When Z Project opens, it prompts for a start and stop slice, which will determine the range of the stack that will be included in the z projection. This process may be used to highlight specific data from the stack and is accessed using "Image/Stacks/Z Project…" Z Project is a method of analyzing a stack by applying different projection methods to the pixels within the stack. There are several ways to "flatten” the 3D stack.
![imagej macro function imagej macro function](https://ai2-s2-public.s3.amazonaws.com/figures/2017-08-08/10870839fb816c8f3e6237b60f1ec8154ade55f1/7-Figure5-1.png)
A montage will allow the 3-D dataset to be visualized in 2-D, but results in each frame being very small. A z-series is generally difficult to represent as a 2-D image for publication purposes.