Quality points are based on the ranking of the player one's beaten. Only players ranked in top 500 are worth quality points. #1 player is worth 100 points, #2 75 points, #3 66 points and so on. At a Slam, the quality points are doubled, so beating #1 is worth 200 points.
Go to WtaTour site, you have it explained in total there. Also check the rankings, there's a total number of quality points for each player, just subtract it from the total number of points and you get the picture.