Change the file type of a picture
You can quickly change the file type of a picture in a web page to GIF, JPEG, PNG-8, or PNG-24 in Microsoft Expression Web.
In Design view, in your web page, right-click the graphic, and then click Change Picture File Type.
If the page references the image by using an absolute URL, such as http://www.example.com/images/example.gif, you can't change the file format by using Expression Web.
In the Picture File Type dialog box, select the file format that you want.
Under Settings, select the options that you want.
For a GIF, you can specify whether to allow a transparent color and whether the graphic is interlaced.
For a JPEG, you can specify the quality and number of progressive passes. The lower the quality you set, the more the graphic will be compressed. The number of progressive passes refers to the number of passes that a web browser will take in order to resolve a graphic as it downloads.
To save the edited picture, on the File menu, click Save to save the page.
In the Save Embedded Files dialog box, set the options you want and then click OK. For more information, see Save an embedded picture.