DPS has an article which is well worth reading. I added a comment to the article which I would like to draw to your attention:
“Here’s how one artist reproduced the Mona Lisa with the extra columns”
It’s interesting to note four things about this reproduction:
1) The “in focus” background is much less pleasant than the original (this subject is covered in the article)
2) The tones are repulsive and sickly. The original (as shown here) has unnatural but warm, pleasant tones: I generally prefer realism, but this reminds me that unrealistic photos can be pleasant. Photographers will benefit from learning which tones are pleasant and which are unpleasant: when photographing people warm (reddish) tones such as light from a sunset are a safe bet (set white balance to Daylight to preserve those sunset tones).
3) The shape of the face, particularly the mouth and nose, makes the subject unattractive. The lower forehead is less pleasant than the original’s. The human mind is drawn to faces in a photo and they are often a make-or-break factor.
4) The subject’s hand that is on the viewer’s left looks claw-like and somewhat creepy. This reminds me that hands are an important factor in photos (the subject is too large to cover in a comment).
The article mentions the idea that the Mona Lisa was originally framed by pillars and with this post I’ve included two examples of framing in portraiture.