Application: How To Adjust Gamma
If your monitor doesn’t have any gamma adjustments, you can skip this step. Hopefully, your gamma is accurate! Otherwise, make sure your preset is 2.2, and ready your meter and software.
To measure gamma, you’ll need to take readings from gray window patterns that range from at least 20 to 100 percent. We measure from 0 to 100 for our reviews. A package like CalMAN automates this process so all you have to do is click one button. If you are controlling your patterns manually, you’ll have to change them between each measurement. Start at the bottom and work your way up. Your software should give you a graph and the raw numbers.
A graph like this one from CalMAN makes it easy to see how close your display is to 2.2. In this example, there are slight dips at 10 and 90 percent. Dips mean that particular point is too bright. Here are the raw numbers from this measurement run.
| Signal Level | Y (cd/m2) | Target Y | Gamma |
|---|---|---|---|
| 0% | 0.40 | 0.00 | 2.20 |
| 10% | 2.02 | 1.53 | 2.08 |
| 20% | 7.36 | 7.02 | 2.17 |
| 30% | 17.35 | 17.13 | 2.19 |
| 40% | 31.73 | 32.25 | 2.22 |
| 50% | 52.06 | 52.69 | 2.22 |
| 60% | 76.9 | 77.38 | 2.21 |
| 70% | 108.99 | 108.89 | 2.20 |
| 80% | 145.97 | 146.33 | 2.21 |
| 90% | 190.37 | 189.88 | 2.18 |
| 100% | 239.68 | 239.68 | 2.20 |
If it were possible to improve on this result, you would have to adjust each point until the Y value matched the target. This example is as good as it gets. But how would you make those tweaks with just presets available? Using multi-point gamma control. We haven’t seen a computer monitor with this feature, but we have used them on a few high-end TVs and projectors.
If you get results like our sample, then you’re ready to move on. If not, try the other presets to see if you can get closer to 2.2. Not every display returns a value of 2.2 just because the preset is labeled that way. You’ll have to do a full measurement run of each gamma option to find the best configuration.
We have our monitor set for maximum dynamic range and correct gamma. Now it’s time to adjust the grayscale.