Load "Media Player Classic," put the DVD into the computer's DVD drive and open it. First set the drive by going up to "View" and then "Options" to open the "Options" menu. Go down to "Playback DVD/OGM" and choose the DVD drive or the "VIDEO_TS" folder where the DVD is located. The VIDEO_TS folder is used if the DVD has been ripped to the hard drive. Pictures can be taken either way. Click "Apply."
Play the DVD by going up to "File"; choose "Open DVD," and the DVD will start playing. If it does not play, you might need to install the proper codecs, which are small programs that allow media players to interface with various different video and audio formats. I recommend the latest version of "Matroska Pack Lite," which is a free package of dozens of codecs that can be installed one or several at a time. The full pack is not recommended, because it has too many conflicting codecs. If you install the codes, the player will usually automatically use them after you restart it.
If the video is too dark or bright, change the color and lighting settings with a filter. Go up to "Play" and choose "Filters," then "MPEG-2 Video Decoder," which will open the filter's Properties window. Under the "Settings" tab, you can change the brightness, contrast, hue and saturation. Click "Apply" to test the colors until they meet your needs. Close this window.
Allow the DVD video to play; pause as needed to take screenshots. A special default feature of Media Player Classic allows you to click directly on the video image to pause and play, without searching for tiny little buttons. The bottom right corner shows the time information, which is useful if you want to write down specific scenes to take screenshots from later. The tracker bar can be tricky to use to get you to the correct scene, but if you know the exact time, you can enter it and have the video start playing from there. Go up to "Play," choose "Go to" and enter the DVD time into the popup box.
Pause the DVD, go up to "File" and click "Save Image." A window will pop up, whereupon you will need to choose a directory to save the screenshot. Enter the name or use the default name, which is the word "snapshot" followed by the current date and the frame number. (This is a great way to archive a large number of screenshots for later use.) Next choose the file type, either JPEG or BMP. Finally, click "Save," and you're done. You can open the pictures with any graphics program.