The easiest way to improve nokia 5800 xm camera's image quality is :

1.Removing the back cover
and
2.Using the night mode in indoors.

Do not increase the contrast. Increasing contrast just improves the sharpness but is of no use.

Have a look at the pics above showing the image quality before and after.

Try it yourself and if you find the difference, Press the thanks button..

For those arseholes and Pussies who think its photoshopped..
See this image below which is photoshopped