Although images have a strong visual impact and are powerful communication devices, it is advisable to keep image sizes (width, height & file size) to a minimum. The larger the image and the higher the quality, the larger the size of the file, and the longer it takes your page to download.
NOTE: There is the option to resize images in the Image Dialog box, we do advise that you don't use this option. Even though the image looks smaller on the page, you are not changing the size of the image but merely changing the space your Web browser allocates for the image. The browser still has to download a large file. If you resize to the correct size in a graphics program prior to uploading you'll change both the image's dimensions and its file size.
The maximum size of any media asset (image, PDF, video etc) that can be uploaded through WebEd is 10MB, images with a file size above 10MB will need to be uploaded by FTP (File Transfer Protocol) to your website. 10MB is a substantial size for an image and it is unlikely that you will be required to do this.