ImageJ Threshold find and replace tool

Is there a way in ImageJ to replace all pixels below a specified color value with another specified color value?

Dear @etterbi,

you could apply a procedure like:

  1. Set a threshold on an RGB image
  • Image > Adjust > Color Threshold…
  • Click Select
  1. Select color for filling: Edit > Options > Colors…
  2. To fill that selection: Edit > Fill


Thanks for your response. However, I see that in the threshold tool you are only able to select generic colors like black, red etc. Is there a way to threshold with a specific color value?

No, but think of the colors in the dropdown as means of visualization for a moment. If you, however, click the Select button, the thresholded region will be shown with a yellow (at least that’s the default color) contour. With steps 2 and 3 mentioned above, you can fill that selected region of interest with any (foreground) color that you like.