Here is how to search a directory and sub directories to find all images and then copy them to another directory using a simple batch file.
Looping through the directory and using Xcopy /Y which copies and overwrites the simple command get the job done.
Save the following code as a .bat file making sure you edit the folder to search and where to save the found images to.
pushd C:\dir\dir2\ for /r %%a in (*.jpg;*.png) do ( XCOPY /Y "%%a" "C:\allimg" ) popd