Howto
Install these programms
sudo apt-get install gnome-raw-thumbnailer ufraw-batch
Try now if everything works, and your thumbnails show up. If not, try the following part.
Fixing missing mime types
In case the default config does not work for you, try this:
Edit the file /usr/share/thumbnailers/raw.thumbnailer as root and insert the following content:
[Thumbnailer Entry]
TryExec=ufraw-batch
Exec=ufraw-batch --silent --size %s --out-type=png --noexif --output=%o --overwrite --embedded-image %i
MimeType=image/x-canon-cr2;image/x-canon-crw;image/x-minolta-mrw;image/x-nikon-nef;image/x-pentax-pef;image/x-panasonic-raw2;image/x-samsung-srw;image/x-olympus-orf;
Check if the mime type of your RAW images in in the MimeType list.
After that, stop nautlius and clear the thumbnail caches:
nautlius -q
rm -rf .cache/thumbnails/* .thumbnails/*
gelioz commentedMar 19, 2017
Replace
nautlius -qwithnautlius -qand extend mimetypes list with following:MimeType=image/x-3fr;image/x-adobe-dng;image/x-arw;image/x-bay;image/x-canon-cr2;image/x-canon-crw;image/x-cap;image/x-cr2;image/x-crw;image/x-dcr;image/x-dcraw;image/x-dcs;image/x-dng;image/x-drf;image/x-eip;image/x-erf;image/x-fff;image/x-fuji-raf;image/x-iiq;image/x-k25;image/x-kdc;image/x-mef;image/x-minolta-mrw;image/x-mos;image/x-mrw;image/x-nef;image/x-nikon-nef;image/x-nrw;image/x-olympus-orf;image/x-orf;image/x-panasonic-raw;image/x-panasonic-raw2;image/x-pef;image/x-pentax-pef;image/x-ptx;image/x-pxn;image/x-r3d;image/x-raf;image/x-raw;image/x-rw2;image/x-rwl;image/x-rwz;image/x-samsung-srw;image/x-sigma-x3f;image/x-sony-arw;image/x-sony-sr2;image/x-sony-srf;image/x-sr2;image/x-srf;image/x-x3f;