I tried to modify the color temperature of one of the monitors (SetMonitorRedGreenOrBlueGain), but not all monitors support it.
For the green mask, you can only achieve it by adjusting the color temperature of the monitor. Two monitors in duplicate mode, no matter how you create the mask, such as using SetLayeredWindowAttributes, it will have the same visual effect on both monitors. As you said, not all monitors support color temperature adjustment (I haven't verified this statement, at least my two monitors support it). So what I want to say is that this is basically difficult to do.
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