Downsample image on import

Is there a way to downsample an image in Fiji on import?
Reason I am asking is that I might need to open images exceeding the allowed image size for Java.
As a workaround I would try to downsample it before it will be displayed. Using BioFormats, I can only crop the image on import but that is not an option in this case, since I do not know the position of the object of interest a priori. Also, I cannot open it tile wise, since the complete object needs to be visible at once.
Images will most likely be either BigTiff or CZI.

Is there any existing solution or any possibility using Ops or Imglib2 to achieve this (I guess something like a CellImg)?