People can insert images and attach files to their documents, blog posts, and discussion messages. Using the admin console, you can configure support for images and attachments.
Admin Console: System > Settings > Attachments
Admin Console: System > Settings > Images
The distinction between images and attachments is important. People can attach to content any file you allow by using the Browse button at the bottom of the content editing page. Attached files will show up as links at bottom of published content, so that others can click to view the attachment. Note that when someone attaches an image, a preview of the image shows with its link. People can also insert images by using the insert image button on the editing page toolbar. Inserted images will be displayed in the content itself, but won't show up as links at the bottom of the page.
Quantity and size. Pay attention to whether larger or more numerous images and attachments make the application slower. If you find that many people are attaching many larger files (and that this is making the application slower), then you might want to create limits by adjusting the size and quantity settings.
Unless otherwise specified, image sizes are specified in pixels and attachment sizes are specified in kilobytes (preview in pixels).
Note that some of the settings are interrelated. For example, if you want people to be able to attach more images to a document than they are currently allowed to, you'll need to make two changes: increase Maximum number of images per object of the Images page and increase Max number of attachments per document on the Attachments page.
Thumbnails and previews. An image embedded in content can display as a thumbnail if it's too big (based on height and width you specify). Images that are merely attached to content can display a preview, which makes it easier for people to see whether it's the image they want before clicking its attachment link. The maximum preview or thumbnail dimensions refer to the height or width of the item -- so a value of 250 means that a thumbnail will not exceed 250 pixels in height or width.
Content type settings let you specify which kinds of content (as determined by their MIME type) should be allowed as embedded images or attached files. You might find that some content file types aren't needed (or are in fact unwanted). You can prevent some kinds of files from being uploaded by "disallowing" them, specifying their MIME content type. If you change these settings, be sure to change it on both the Image and Attachments pages.