For anybody that's willing to give it a go it's a simple 1366x768 image with the following gradient 0%-#000000,25%-#333333,75%-#252525,100%-#000000
Based on your specs I created a new background in Photoshop (it's attached).
This is how:
- Create a new picture
- Image mode on grayscale
- Image mode 16 bits/channel
- Filled with your gradient
- [File][Save for web & devices]
- PNG-24
- no transperancy selected
- Not interlaced
- [Save]
On my tv it looks way sharper
Best Yuri