AutoRay has the ability to compress your images before they are burned onto a disc.
By default, this feature is off. To enable this feature, click Configure and select the tab "Media" on top.
On the bottom of the page check the box "Compress Image SOP Classes Before Adding to Media". You can then select the "Quality Factor" amount. The lower the number, the smaller the file size, but the greater the loss in quality.
The "Lossless compress when possible" button will attempt to intelligently decide if an image requires further compression or not.