You probably have two different folders, named Video_TS and Audio_TS if this is a standard DVD.
If you want each individual still picture, you would need to use a video player that has a capture function. In VLC media player (which is free to download and use), you would play the movie until you get to the picture you want, then pause playback. Then go to the control bar at the top of VLC media player and click on Video-->Take Snapshot. You should be aware that the quality of the snapshot is not going to be as good as the original picture.