82915G / Setting brightness of VGA signal

[claude_boulard]

Hi.

I'm a vision engineer.

For a project I use a computer with an Intel 82915G controller, integrated on the mother-board.

For technical matters, I had to set, by software,the level (brightness) of the VGA signal produced by the 82915G controller.

This is possible with the Control Panel (Display/Property/Graphic adapter/Colors ...), so I think it should be accessible from my software (written in Microsoft C++).

Do you know a simple access, from software, to that specific VGA controller setting ?

Thanks for your answer.

[Chuck_De_Sylva]

The control panel is actually adjusting the gamma settings, _not_ the brightness. Brightness is something that is controlled through the display driver to the monitor itself via I2C signals. There are some brightness calls in the VESA spec for controlling the monitor's brightness, however very few, if any vendors that implement this. Typically for laptops and such that implement this they use proprietary VBIOS calls to make this feature work.

- Chuck

[grant_jorde]

True, laptops are concerned with setting the LCD backlight brightness usually in order to try and save battery power. If this person is only concerned with visual brightness, then adjusting the perceived brightness via the gamma tables would be fine. The Win32 software call to do that is SetDeviceGammaRamp:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/icm/icm_0yi8.asp