Later this month we are planning to make a new release of Page Saver. This new release of Page Saver, when run in Firefox 2, will let you control whether transparency information (also known as the alpha channel) is included in saved PNG images. You will be able to control this from the options window as well as the command line. If you choose to include transparency information, PNG images will be saved in RGBA format; otherwise the format will be RGB.
In previous versions, Page Saver always included a transparency layer but the images did not include any transparent areas. In the new release we plan to exclude the transparency layer by default which will reduce the size of the files produced. Please let us know if omitting the transparency information will cause any problems for you.