Alright. A photo-realistic image implies 3D visualization aka rendering. SketchUp doesn’t have an in-built renderer unforutnately, so we use plugins for that. There are hundreds of them and some of the best ones on the market are:
- V-Ray, whose newest 3.4 version for SketchUp is currently in beta testing, to be released sometime in January 2017
- Podium which is a great alternative, and I’ve recently been told that the newest 3.0 version will include a Live Material Preview which has been missing from the start
- Indigo Renderer
If you follow this link, you will find a long list of rendering engines that are supported by SketchUp.
Personally, I’ve tested most of them to see if one is better than the other but in the end I still silently come back to V-Ray because it produces the best desirable result and is considered a market-standard.
Kerkythea is another one and it’s free, but it has a learning curve. Nonetheless, if you’ve mastered it, you can achieve great results. Have a look at @DaveR’s wonderful gallery for a proof.
Cheers. 