Now that images have been integrated directly into Drupal core, you can configure various image styles to control the size and appearance of images that are attached to the content. Similar functionality could be achieved in Drupal 6 by installing the Image and Image Cache modules. To access the image styles, click on Configuration from the administration toolbar and then click on Image styles in the Media section. You will receive a list of the styles that are currently defined:
Drupal 7 ships with the thumbnail, medium, and large image styles by default. These set the maximum size of images as follows:
Thumbnail—100 x 100px
Medium—220 x 220px
Large—640 x 640px
No changes are made to the original images other than resizing them, and the aspect ratio of the original image is preserved.
To create a new image style, click on the Add style link and give the style a name. The name must be machine readable and consist of letters, numbers, and underscores. After the style has been created...