Creating thumbnails on the consumer level DiskStation NAS boxes by Synology is incredibly slow which makes indexing large photo collections take forever to complete. It's much, much faster (days -> hours) to generate the thumbnails on your desktop computer over e.g. SMB using this small Python script.
Install Python 3 onto your machine and then open a terminal so that you can install the Pillow. You can use the following command to install it: pip install Pillow
# Run the following command in your terminal. Path is the path to the folder you want to generate thumbnails for
python3 dsthumbgen.py --directory <path>
# Example on Windows
python3 dsthumbgen.py --directory C:\Photos\Given a file and folder structure like below:
C:\Photos\001.jpg
C:\Photos\dir1\002.jpg
...the utility will create the following:
C:\Photos\eaDir_tmp\001.jpg\SYNOPHOTO_THUMB_XL.jpg
C:\Photos\eaDir_tmp\001.jpg\SYNOPHOTO_THUMB_B.jpg
C:\Photos\eaDir_tmp\001.jpg\SYNOPHOTO_THUMB_M.jpg
C:\Photos\eaDir_tmp\001.jpg\SYNOPHOTO_THUMB_PREVIEW.jpg
C:\Photos\eaDir_tmp\001.jpg\SYNOPHOTO_THUMB_S.jpg
C:\Photos\dir1\eaDir_tmp\002.jpg\SYNOPHOTO_THUMB_XL.jpg
C:\Photos\dir1\eaDir_tmp\002.jpg\SYNOPHOTO_THUMB_B.jpg
C:\Photos\dir1\eaDir_tmp\002.jpg\SYNOPHOTO_THUMB_M.jpg
C:\Photos\dir1\eaDir_tmp\002.jpg\SYNOPHOTO_THUMB_PREVIEW.jpg
C:\Photos\dir1\eaDir_tmp\002.jpg\SYNOPHOTO_THUMB_S.jpg
eaDir_tmp is used as a temporary directory name as @ characters are not valid in file names on Windows. Therefore these folders must be renamed to @eaDir for PhotoStation to recognize them. This renaming process must be done via SSH to the DiskStation unless the volume is mounted by NFS. Useful commands:
# Remove any existing thumbnail directories, dry-run check print out before running next command!
find . -depth -type d -name 'eaDir_tmp' -execdir echo '{}' \;
# Remove any existing thumbnail directories
find . -depth -type d -name 'eaDir_tmp' -execdir rm -rf '{}' \;
# Rename directories
find . -depth -type d -name 'eaDir_tmp' -execdir mv '{}' @eaDir \;