Segmentation of masonry walls

Hi! I’m triying to segment this image in order to isolate the stones from the background, which is quite easy to do manually, but time-consuming. I’m a newbie to Fiji, do you think it would be possible to automate the process? If so, do you have any recomendation on which tools I could use?
Thanks in advance!
masonry-sample.tif (4.0 MB)