1. Programs and Downloads
First, you need to download and install Spriter, a free 2D animation program from BrashMonkey. It can be used to access the sprite animations and export them for example. You can find and download the newest versions here.
Second, you need to download Simplex' ktools to be able to convert the game files into Spriter project files. These are found here, but you need to have an user account at the Klei Forums to be allowed to download them. Their readme with more detailed information can be found here.
ktools contains two programs: ktech and krane. ktech can be used to convert bidirectionally between TEX files (without animations) and PNG, but this can also be more easily done using Matt's TEX Tools. So krane is actually what we are looking for. It has recently been updated to support animations with more than four sides (for example the eight-faced walls in DST and SW).
2. Get the files
krane needs three input files in order to create a working Spriter project file.
These can be found packed in zip files in:
C:\Programs\Steam\steamapps\common\Don't Starve Together\data\anim
Copy the zip file of your choice into another folder (always create a safety backup!), then unzip it. You should now have three files:
If you are missing the anim file, then this object/mob/etc. you're trying to extract may have other versions or states in a different zip file. For example, Snow and Shadow Chester have their own atlas and build, but use the anim of the standard version, because their motions are the same. So you may need to copy another zip file and unzip it, but only use the anim file, be careful not to overwrite the other two.
3. Get krane to work
Now it's getting a bit weird. Open cmd.exe and enter the following input all in one line:
Then execute. If the output folder doesn't exist yet, it will be created automatically.
If everything worked and krane says "Done.", you will find a bunch of folders in your chosen output folder and a scml file. This is the project file you can now open in Spriter.
4. In Spriter
Opening the project file, you should now see the object in the main animation window. In the down right corner you should see a list of available animations.
Let's say, if you need to extract only one frame for a wiki page for example, choose the Idle animation, then go to
File > Export Animation To PNG/GIF...
Set Source frames > images to 1 and then hit Export. You should now get a PNG file of the first frame of the Idle animation.
Of course, you could also export animations to GIF files and what not, but I have to admit, that this is all the experience I had with Spriter so far. So as I am not an expert, if there is any way to make this process easier or shorter, please let me know. Also if there are any questions or problems, please don't hesitate to ask.