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Getting Started


First, you should to install ImageJ!

The main window

After starting ImageJ, you will see the main window:

On Mac OS X, the menu bar will appear on the top of the screen (as with all OS X applications).

The menu bar

In the menu bar, you will find most of the functionality, such as loading/saving files, processing them, and plugins will be installed into the menus, too.

The menus have different purposes:

File input/output, new files

Selection/ROI handling

Visualization, stack manipulation

Image filters


Plugins, Macros and Utilities


Help & Links

The tool bar

The toolbar mostly contains selection tools: the rectangle, ellipse, polygon, freehand and straight line selection tool. By clicking on the icon, you activate the tool.

Some tools offer option dialogs which you can open by double clicking the icon. This example shows the option dialog of the Oval Tool:

If there is a small red arrow in the lower right corner of the tool icon, you can right-click (Ctrl +click on an Apple mouse) and select an alternative selection tool (e.g. a circular brush selection tool which shares the icon with the ellipse selection tool). Example:

The status bar

The status bar displays useful information at startup, and when running plugins. It also shows a progress bar on the right side for long-running processes:

A single mouse click on the status bar will show the information about ImageJ and Java version as well as about memory consumption:

Drag & Drop

You can drag files from your favorite file manager and drop them on the main window; ImageJ will load the corresponding files.

Drag ‘n Drop will also work for images displayed in your web browser, unless they are links to other web pages. You can try with this page: clicking on an image will open a page whose image you can Drag ‘n Drop into ImageJ’s main window.

Image windows

Whenever you open an image, be it via FileOpen , Drag ‘n Drop or FileOpen Samples , ImageJ will open an image window.

The window has the file name as title, and it display some useful information above the image: the real resolution (in this case in square centimeters), the pixel resolution, the image type and the memory required by the image.

If your image does not have meta-data about the real resolution, you can set the resolution explicitely with ImageProperties… or by following the tutorial on spatial calibration.

Image Types

You can change the image type:

Choose between

  • 8-bit (intensity range 0..255)
  • 16-bit (intensity range 0..65535)
  • 32-bit (floating point numbers)
  • 8-bit color (up to 256 colors encoded via a color lookup table)
  • RGB color (3 colors encoded as 8-bit values)

There are two more options: RGB stack and HSV stack, which can turn a 2-dimensional color image into a stack consisting of 3 color channels (red, green & blue or hue, saturation & value, respectively).

Further reading

Have a look at the list of tutorials on this Wiki.