If you plan to share your pictures in Microsoft Office documents, on Web sites, or in e-mail messages, you may want to reduce the size or dimension of your pictures to work more efficiently. For example, if you take pictures with a digital camera that creates large files, putting those files into a Microsoft Word document can make the Word document difficult to manage because of its increased file size. You may want to reduce the file size of your pictures so that they load faster on Web sites or reduce the dimensions of your pictures so that they fit better in a browser window.
You can change both file size and picture dimensions by compressing the files to a smaller JPG format. Microsoft Office Picture Manager automatically determines the amount of compression after you specify how you intend to use the pictures. The aspect ratio of your pictures will always be maintained. If your picture is already smaller than the compression option you have chosen, no resizing or compression will be performed.