Nautilus isn't displaying thumbnails for my NEF files (photo raw)

By default, Ubuntu doesn’t display thumbnails for NEF files. But you can try (as explained in this blog post) installing UFraw.

sudo apt-get install ufraw

And if itś not already existing, create a thumbnailer file /usr/share/thumbnailers/ufraw.thumbnailer, with content :

[Thumbnailer Entry]
Exec=/usr/bin/ufraw-batch --embedded-image --out-type=png --size=%s %u --overwrite --silent --output=%o
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-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-sigma-x3f;image/x-sony-arw;image/x-sony-sr2;image/x-sony-srf;image/x-sr2;image/x-srf;image/x-x3f;

This file basically say to exec ufraw-batch (with the good parameters) on any file with the specified mimetypes (including image/x-nef).

Okay, most of the answers here either don't work from Ubuntu 19.10, or are slow because they process the RAW files.

NEF files (and probably lots of other formats) have embedded JPEG's previews in them, which is a lot faster to extract. And lo' and behold, the default thumbnailer for Gnome supports them, but they're not enabled, here's how to enable it:

• you have to edit the file /usr/share/thumbnailers/gdk-pixbuf-thumbnailer.thumbnailer to add the missing MIME types.
• Here's the file before:

[Thumbnailer Entry]
TryExec=/usr/bin/gdk-pixbuf-thumbnailer
Exec=/usr/bin/gdk-pixbuf-thumbnailer -s %s %u %o
MimeType=image/png;image/bmp;image/x-bmp;image/x-MS-bmp;image/gif;image/x-icon;image/x-ico;image/x-win-bitmap;image/vnd.microsoft.icon;application/ico;image/ico;image/icon;text/ico;application/x-navi-animation;image/jpeg;image/x-portable-anymap;image/x-portable-bitmap;image/x-portable-graymap;image/x-portable-pixmap;image/tiff;image/x-xpixmap;image/x-xbitmap;image/x-tga;image/x-icns;image/x-quicktime;image/qtif;

• You may append just image/x-nef;image/x-nikon-nef; for NEF if you want, or you can add all RAW formats (I just did that):

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;

You can install the following packages, and Nautilus will start displaying thumbnails for NEF files without having to do any manual configuration.

18.04 and newer:

sudo apt install libopenraw7 libopenrawgnome7 gnome-raw-thumbnailer

It seems the libopenraw1 and libopenrawgnome1 are no longer available in 18.04 and above, they were replaced by libopenraw7 and libopenrawgnome7. In fact, the 2 libraries don't seem to be required to generate the thumbnails and can be skipped. However, if you include them, the generation of the thumbnails becomes much faster.

16.04 and earlier:

sudo apt-get install libopenraw1 libopenrawgnome1 gnome-raw-thumbnailer

source: Ubuntu Foums - viewing nikon NEF raw files?

At ubuntu 18.04 just install gnome-raw-thumbnailer:

sudo apt-get install gnome-raw-thumbnailer

ufraw is no longer available so in order to have thumbnails in nautilus in 20.04 you need something different. I'm using dcraw, however it only converts to ppm or tiff. And the gnome thumbnails need to be png. So in this solution I use ImageMagic convert.

Here is my solution:

1. Install dependencies:

sudo apt install dcraw ImageMagick

2. create a script to combine the 2 commands

sudo nano /sbin/rawthumbnailer

and put the paste the following in it:

#!/bin/bash

/usr/bin/dcraw -c -w -v -h $1 | /usr/bin/convert - -resize x$2 png:$3

Don't forget the execution flag:

sudo chmod +x /sbin/rawthumbnailer

3. create the thumbnailer script in /usr/share/thumbnailers:

sudo nano /usr/share/thumbnailers/raw.thumbnailer

The contents should read as this

[Thumbnailer Entry]
TryExec=/sbin/rawthumbnailer
Exec=/sbin/rawthumbnailer %i %s %o
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;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;

4. Restart nautilus:

nautilus -q

If you tried before and didn't succeed you should delete the thumbnails

rm -rf ~/.cache/thumbnails/*

or at least the failed thumbs dir

rm -rf ~/.cache/thumbnails/fail

The script needs to be in /sbin, /bin or /usr... as the generation is happening using the bwrap and there are only some directories binded in it. I tried to follow this to have the script in home, but it didn't work for me.

Also I was unable to make it work without the script file. Not sure if it is possible or not, but I prefer to have a simpler solution with less files if possible.