This document explains guidelines for images included in your KB documents, including standards for formatting, sizing, and displaying.
Use the .png format if possible, otherwise use one of the following file formats: .jpg, .gif.
If possible, try to make your images no wider than 600px. This ensures that users with XGA resolution (1024x768) displays can view your content without a scroll bar and is more accessible for smartphone users.
The size of the image must be under 125MB when using the the multi-select uploader in Firefox, Chrome and Safari. A progress bar will display a confirmation (or error) message.
Unfortunately, this does not work in IE, so IE will not have any multi-select feature and is still limited to 40MB files.