The "Caption" of new versions of Wordpress is to actually create a frame around your image but also to display a caption in the same context gray. This can sometimes distort the graphic blogs like this blog for example. Via MyDigitalLife

You will also notice that if you fill in the "Legend" which is the tag "alt" to your images, this module will automatically "caption." Therefore the subsequent clean up your code for displaying perfect images.

This script is for people using the new versions of Wordpress (2.6) but also those who have a charter graphics to respect and want to gain a few seconds during the drafting of article.

The PHP code is to be included in your file "functions.php" of your theme, or in the file "wp-config.php. He then disable the "caption" of your images and your videos.
Updated from the article: If you have the latest version of Wordpress 2.7, insert this code.

  add_filter ( 'disable_captions',' caption_off '); 
  caption_off function () ( 
  return true; 
  ) 

If you have version 2.6, insert this code.

  define ( 'CAPTIONS_OFF', true);