I read thru this thread and started to play with the image as presented. As mentioned, this is a very low quality image to begin with. Obviously,, you want to start with as much information in an image as possible.
I tied a few things just to see what's possible. I'm not a high level expert but it gives me a chance to flex a bit.
One thing to agree on - you can't bring back something that doesn't exist.. You can play some tricks with sharpening, but without some detail, you may end up with a harsh finish.
So using the image you posted, I decided to look at it just in terms of color. What stands out are the reds and yellows. So I played with that, emphasizing those colors to create a visual contrast.
It comes off as a bit impressionistic. i know it's not exactly what you want - but it gives the eye something to focus on.
Only other option is what [USER=69670]@IamSam[/USER] mentions is to go back to the original and change up your filter settings.
Any way, just a journeyman's opinion... 
- Jeff
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