Render quality question

[i777]

Hi all,

In my work I normally use Showcase and Vred, however I've recently been introduced to Keyshot by a colleague who uses it.
I'm very impressed and enjoy using Keyshot. I've been trying some renders of car models (Alias wire files) and have a question re. quality.
To try and get some nice clean renders I've been using the 'Max Time' render, set to 5 hrs (1920x1080 pixel image at 100dpi). When the image is rendering it looks awesome and has very smooth clean edges and lines etc - however when it's complete and I open the final image (I've been setting it for jpg image) some of the detail and lines are very clean while some others are coming out quite pixelated and jagged.
I don't quite understand how it can look so amazing as it is rendering, and then the final image isn't as good ??

Any help or advice very welcome.

Thanks.

[thomasteger]

Can you share an example? Also, have you tried other image file formats?

[i777]

I've tried to attach a small 'swatch' of the render here - can't reveal too much of what it is.
The only other file format I used was Tiff, but obviously didn't get the background with that. For pixelated lines it was the same though.