The RGB output form the VCE is extremely crisp. Any softening through a converter is due to filtering in the IC design. Using a slow amp and/or caps, etc. Could be frame grabbing/digitizing device that's outputting from a frame buffer. Any number of things. You would need to provide a lot more details to get any real answers.
SHUTTLECOCK OR SHUFFLE OFF!
Here: http://www.mmmonkey.co.uk/console/pce/rgb.htm