The best way to translate text from a TV screen is to use Google Translate app on a smartphone or tablet. Set it to JP -> EN and pick the camera option and point the camera to the text on the screen.
If you cannot get a clear image with your phone/table camera, you will need to type in the text in the Google Translate website.
To input Japanese text, you can use these websites:
If you want to translate from screenshots on your PC, you need to get the image through OCR and then copy-paste the text in Google Translate. A good OCR site for this is: http://www.newocr.com/
OCR isn't perfect, so always compare the results with the image to delete any extra Kanji/Kana that might have been generated or to check for wrong characters. If you need to input a Kanji, try Lexilogo Kanji charts. Count the number of lines in the Kanji and input that number in the "Strokes" dropbox, then find the Kanji in the list it shows.