ios - 如何更改whiteBalanceGains值？

我收到错误消息:

- whiteBalanceGains contain an out-of-range value. Red, green, and blue gains must be in the [1, maxWhiteBalanceGain] range

如何确定maxWhiteBalanceGain范围？

AVCaptureDevice *device =
[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
AVCaptureWhiteBalanceTemperatureAndTintValues temperatureAndTint = {
    .temperature = 8000,
    .tint = 146,
};

[device deviceWhiteBalanceGainsForTemperatureAndTintValues:temperatureAndTint];

[device setWhiteBalanceModeLockedWithDeviceWhiteBalanceGains:[device deviceWhiteBalanceGainsForTemperatureAndTintValues:temperatureAndTint] completionHandler:^(CMTime syncTime) {

 }];

最佳答案

rom苹果开发人员文档

“请注意，尽管某些温度和色调组合会产生超出范围的设备RGB值，如果将其直接传递给setWhiteBalanceModeLockedWithDeviceWhiteBalanceGains:completionHandler:，将导致引发异常。请确保检查红色，绿色和蓝色增益值是否在该范围内为[1.0-maxWhiteBalanceGain]。

所以，首先，您必须获得白平衡增益

AVCaptureWhiteBalanceGains wbGains = [device deviceWhiteBalanceGainsForTemperatureAndTintValues:temperatureAndTint]

然后，检查wbGains.redGain, wbGains.blueGain, wbGains.greenGain是否在[1 ... maxWhiteBalanceGain]范围内。
maxWhiteBalanceGain是AVCaptureDevice对象的属性。