How does Nvidia software adjust the brightness and contrast?

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cpthk

Weaksauce
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Jun 9, 2008
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I saw the nVidia control panel has the ability of adjusting the brightness and contrast. I wonder how does it achieve that? I thought HDMI/Displayport only output the color code of each pixel to the monitor, and the brightness and contrast is controlled by the monitor setting. Is this not true? Or it's just to adjust the color to more white or black to trick human eyes to feel brighter?

Thanks.
 
It doesn't actually change the brightness or contrast of the monitor, it is altering the color data before sending it to the monitor. My understanding is it works like a software LUT. You can see that your backlight brightness doesn't change even when you turn brightness all the way down in the NVIDIA control panel.
 
Its nice when it works no idea how it works GPU controls the signal so it adjusts it from there I suspect. Lately I had to go into Win 10 system command and make sure Windows 10 doesnt overide it. I wish Win 10 had a decent gamma adjuster.

My Nvidia setting are like 20 contrast 20 brightness and .71 gamma run it's higher on my gaming monitor.
 
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That's what I was suspecting. I feel like they should call it something else instead of "brightness". Brightness' definition is how much light coming out of it, which is closer to the monitor's backlight. The "brightness" here isn't the same as the actual monitor's "brightness". I also looked up the HDMI protocol, there isn't data of brightness of the pixels being sent to the monitor. This made me think it's a color altering trick.

Armenius said:
It doesn't actually change the brightness or contrast of the monitor, it is altering the color data before sending it to the monitor. My understanding is it works like a software LUT. You can see that your backlight brightness doesn't change even when you turn brightness all the way down in the NVIDIA control panel.
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Gamma adjusts, basically. Don't change it, it's crushing the picture.
 
It's still brightness control. The color data tells the monitor how much light to display from each sub pixel.

If an LCD backlight at 100% can output 100 units of light, a subpixel color value of 256 will allow 100 units of light to pass.
If you reduce the brightness to 75%, that same subpixel color value of 256 will only have 75 units of light passing through it.
If you instead you use software to limit the brightness to 75%, the subpixel color value will be limited to 192.. blocking 25 units of light and allowing only 75 units of light to pass.

An emissive display (OLED, CRT, PDP, etc) is similar, except the electronics affect the subpixel ability to emit light directly.

Of course the real world is not near as clean, so you get washout, crushing, shifting, blooming, etc, but in general the effect of brightness control, whether done in software or hardware, is to manipulate the color data in some way to increase or limit the amount of light coming from the display,.
 
Do not touch them. Leave them in stock settings. They are basically gamma controls, except where gamma adjusts the midtones the contrast and brightness adjusts the bright end and low end, in this order even if it seems odd that brightness controls the low tones.

If you increase brightness, it elevates the black level which neuters your contrast ratio. And if you reduce it, it pushes the low end tones towards number 0, absolute black. However you cannot go below 0 so the dark colors simply get clipped. You get black crush.

Contrast is the same, except reverse. If you increase it, high tones get pushed towars the pure white, number 255, and clipped away as they reach it. And lowering lowers the white point down, again neutering your contrast ratio.

Turning the contrast slider up and brightness slider down may give a more "contrasty" popping picture because the midtones get stretched towards both ends but you are cutting away details on both ends.
 
I've only touched mine when my Asus TN monitor had too high a back-light at zero setting.

I had to set it at like -20 :(

LED backligths are way too bright!
 
whateverer said:
I've only touched mine when my Asus TN monitor had too high a back-light at zero setting.

I had to set it at like -20 :(

LED backligths are way too bright!
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This doesn’t make sense because the control panel cannot actually reduce the minimum black level brightness for actual black. It can only crush the near black grays so they are all just black (again no darker a black than if you left it alone). You could achieve this better by choosing a monitor mode with a higher gamma (like 2.4) and making sure the PC isn’t set to video levels (16-235) instead of pc level (0-255).
 
sethk said:
This doesn’t make sense because the control panel cannot actually reduce the minimum black level brightness for actual black. It can only crush the near black grays so they are all just black (again no darker a black than if you left it alone). You could achieve this better by choosing a monitor mode with a higher gamma (like 2.4) and making sure the PC isn’t set to video levels (16-235) instead of pc level (0-255).
Click to expand...

I already chose the lowest brightness monitor mode. It was still too-bright for my dark room. I had to do this on my LED backlight LCD tv from 2011.
 
Nvidia brightness, contrast, gamma settings do not effect the actual monitor hardware. Meaning if you have monitor settings at full brightness and drawing 80w power, but reduce brightness from Nvidia controls, it will still draw 80w power. Adjusting these settings directly from the monitor is the better way. Doing it from Nvidia driver software may reduce the visual brightness but will affect the contrast and gamma as well. Investing in a good colorimeter and calibrating the monitor will ensure you dont have such issues and having best contrast and gamma balance to the brightness.
 
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