Lo and behold ... the only surviving shot from the Lindsay Lohan Playboy photo shoot that hasn't been touched up by professionals ... and it might be the best one of the entire spread.

The pic was taken behind the scenes during Lindsay's 2-day shoot back in November -- right before she disrobed for a Marilyn Monroe-inspired spread.

The final shoots were leaked onto the web yesterday -- and while Lindsay looks good, it's obvious they were photoshopped like a mutha.