Invert intensity of each pixel. This uses the stock ImageJ intensity inversion function ("Edit > Invert")
Input image: Image to be inverted.
Apply to input image: When selected, the input image will be replaced by the inverted image in the workspace. If disabled, the inverted image will be stored as a new image in the workspace.
Output image: If "Apply to input image" is not selected, the inverted image will be stored as a new image in the workspace. This is the name of the output inverted image.