Different names of source and destination folder

I have 2 dirs with different pics: let’s say /original_pictures and /optimized_pictures. How I can build a site with _site/pics as destination dir for the contents of one of them? The idea is to switch source dirs depending on different env (or _config), but preserve destination dir name the same.

not sure you can with jekyll, but maybe with Gulp. You could have gulp minimize the images from the originals folder and put them in the pics folder.

I use gulp for all asset processing as it is much quicker - so sass, js and images are all handled by gulp, and I have jekyll ignore the source folder, and also keep the site folder for them.

Yes. I solve that with Gulp and symlinks for now, thanks. But from my point of view it is too common task to automate it with Gulp. I wonder if some “mount/unmount” mechanism exist or not. Like include section in _config.yml but with destination.