Muhammad Sajjad:

I hope Rob's answer helped solve the problem of adjusting the LCD contrast for you. I have used the level adjust register in a similar part and it works well.

You may also be interested in a project I did with a graphics display using the Samsung S6B0724 controller, which is very similar to your S6B0719 chip. Check out my project page at http://www.8052.com/users/mkaras/GraphLCD.phtml .

Michael Karas