FAQ: How do I set up ImageJ to deal with white particles (on a black background) by default?

ImageJ can be set to deal with white particles on a black background or black particles on a white background. The latter is the default. How do I change that?

Check the Process>Binary>Options>Black Background option.

Once this is set, the Make Binary and Convert to Mask commands will set the thresholded areas to white and the background to black (without using the Inverted LUT). This option will also define what pixels are eroded/dilated/opened/closed (regardless of their greyacale values; note that when using the Inverted LUT, “white” has pixel value [0] instead of [255]).
It may be convenient also set the default foreground and background colors with Edit>Options>Colors…

To make these changes permanent (i.e. each time you run ImageJ), you can use the Plugins>Macros>Record… command to record these settings and paste them in the AutoRun macro in the StartupMacros.txt file (you find this file in the /ImageJ/macros/ folder).

The macro would look like this:

macro "AutoRun" {
run("Options...", "iterations=1 black count=1"); //set black background
run("Colors...", "foreground=white background=black selection=yellow"); //set colors
run("Appearance...", " "); //do not use Inverting LUT
//add more commands here if needed
}

Note: if you distribute your macros and use the method above to set default options, then other users have to know your Autorun settings, otherwise, their defaults will be different and the macro may not run as intended.

One possible solution is to paste the AutoRun set of commands at the start of your macro. The disadvantage is that this may override the current settings of the other users without them knowing.

Two macro commands:

saveSettings();

and

restoreSettings();

may be useful to save the current state of ImageJ:

  1. add saveSettings(); as the first command of the macro to save the other user settings,
  2. then add your AutoRun commands (so the defaults in the user machine are the same as in yours),
  3. then add your macro commands, and
  4. finally restore the user original settings with restoreSettings(); at the end of the macro.
faq/technical/how_do_i_set_up_imagej_to_deal_with_white_particles_on_a_black_background_by_default.txt · Last modified: 2013/10/17 11:15 by jan
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