On the keyboards of most laptops there are buttons for the display settings, but they concern only the brightness. Contrast you can change in the settings of the driver installed on your computer graphics card.
In the case of the graphics card manufacturer Nvidia, the contrast is adjusted using the control panel of your video driver. Click the right mouse button or touchpad on the desktop, and then select the option called "Nvidia control Panel".
Go to the menu item "adjusting the color settings in the desktop by using the links at the left side of the window. Then select "Use Nvidia settings" and increase contrast in the corresponding item in the slider to the required level.
In the case of the card manufacturer ATI first download the latest version of the Catalyst video driver. Function in this case is the same as the Nvidia control panel. Go to the Color tab, located on the left side of the program window. Now you can adjust the contrast in the corresponding item (Contrast) using the slider. After configuring the contrast, save the changes.
If your netbook has integrated Intel Graphics, video driver settings, select the item called "Graphics options", then "color Settings". Here (again, using the slider) the contrast can be adjusted at discretion.
If you need to increase the contrast during viewing of presentations of individual pictures or videos and films, use the functions of the application through which you view a particular file. For example, in VLC player access contrast settings as follows: click with the left mouse button or touchpad to point me the "Tools" and select the sub-item Extended Settings. In many programs, the contrast can be adjusted by following the chain of menu items: "Options" -> "picture settings" (or "display settings").