Prohibit wordpress4.4 + version automatically generates a 768 pixel thumbnail

4.4 version later, wordpress added a responsive picture function, the purpose is to allow the picture to adapt to the phone, tablet and other different screens, you upload the picture will automatically generate a 768 pixel thumbnail, but I do not want this feature, the Thumbnail size is fully adjusted to 0, prohibit wordpress automatically generate thumbnails, upload pictures or will generate a 768 pixel thumbnails.

This problem I find a long time did not find a solution to study the day, finally resolved.
In the document wp-admin \ includes \ schema.php Lane in the following code, you can see is 4.4 new features.

  1. // 4.4.0
  2.     ‘medium_large_size_w’ => 768,
  3.     ‘medium_large_size_h’ => 0,

This is the default option to install wordpress, but there is no place to change in the background, there is no change code, because it has been deposited into the database, so go into the database.
Enter the command to change the value of medium_large_size_w to 0 on the line
SQL commands are as follows:

  1. SELECT * FROM `wp_options` where option_name=’medium_large_size_w’

Prohibit wordpress generation 768 pixel thumbnails can effectively save the site space, especially those pictures of many sites (such as the theme of the cat wordpres theme download station) need to prohibit this thumbnail.