Currently, this is not possible as Aspose.Slides for Reporting Services follows the TIFF behavior. However, if your concern is related with the charts, it has already been reported to the product development team with issue id 7262. If you desire, this thread can be associated with this issue to get notification as soon as it is resolved.
Thanks for your speedy response. I would appreciate if you could associate this thread. I am definitely waiting for this feature.
The thread has been associated with the issue 7262 and you will be autoresponded as soon as a release with this fix is published.