Android Camera2 API 设置自定义亮度、对比度、伽玛

Question

由于 this 没有明确的答案，并且 stackoverflow 没有关于 Camera 2 API Gamma 的问题/答案，我要求使用Android Camera 2 API 修改亮度、对比度和 Gamma 的解决方案。
我获取 range 和 step 的代码：

Rational controlAECompensationStep = characteristics.get(CameraCharacteristics.CONTROL_AE_COMPENSATION_STEP);
if (controlAECompensationStep != null) {
    compensationStep = controlAECompensationStep.doubleValue();
}

Range<Integer> controlAECompensationRange = characteristics.get(CameraCharacteristics.CONTROL_AE_COMPENSATION_RANGE);
if (controlAECompensationRange != null) {
    minCompensationRange = controlAECompensationRange.getLower();
    maxCompensationRange = controlAECompensationRange.getUpper();
}

我设置亮度百分比的方法：

public void setBrightness(int value) {
    int brightness = (int) (minCompensationRange + (maxCompensationRange - minCompensationRange) * (value / 100f));
    previewRequestBuilder.set(CaptureRequest.CONTROL_AE_EXPOSURE_COMPENSATION, brightness);
    applySettings();
}
private void applySettings() {
    try {
        captureSession.setRepeatingRequest(previewRequestBuilder.build(), null, null);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

但是这种方法不能正常工作。图片变成green，就像here。

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我描述了我在 documentation 中找到的所有内容（包括演示 .apk）。

Answer 1

我的错误是在修改亮度（B）、伽玛（G）或对比度（C）之前将Auto White Balance Mode(AWB)更改为CONTROL_AWB_MODE_OFF。
不要为AWB 设置OFF 模式，使用AUTO 或其他可能的模式。

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获取当前 B 的百分比

public int getBrightnessValue() {
    int absBRange = maxCompensationRange - minCompensationRange;
    int value = getValue(CaptureRequest.CONTROL_AE_EXPOSURE_COMPENSATION);
    return 100 * (value - minCompensationRange) / absBRange;
}

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以百分比设置 B

public void setBrightness(int value) {
    int brightness = (int) (minCompensationRange + (maxCompensationRange - minCompensationRange) * (value / 100f));
    previewRequestBuilder.set(CaptureRequest.CONTROL_AE_EXPOSURE_COMPENSATION, brightness);
    applySettings();
 }

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以百分比设置 C

//set def channels (used for contrast)
TonemapCurve tc = previewRequestBuilder.get(CaptureRequest.TONEMAP_CURVE);
if (tc != null) {
    channels = new float[3][];
    for (int chanel = TonemapCurve.CHANNEL_RED; chanel <= TonemapCurve.CHANNEL_BLUE; chanel++) {
        float[] array = new float[tc.getPointCount(chanel) * 2];
        tc.copyColorCurve(chanel, array, 0);
        channels[chanel] = array;
    }
}

public void setContrast(int value) {
    final int minContrast = 0;
    final int maxContrast = 1;

    if (channels == null || value > 100 || value < 0) {
        return;
    }

    float contrast = minContrast + (maxContrast - minContrast) * (value / 100f);

    float[][] newValues = new float[3][];
    for (int chanel = TonemapCurve.CHANNEL_RED; chanel <= TonemapCurve.CHANNEL_BLUE; chanel++) {
        float[] array = new float [channels[chanel].length];
        System.arraycopy(channels[chanel], 0, array, 0, array.length);
        for (int i = 0; i < array.length; i++) {
            array[i] *= contrast;
        }
        newValues[chanel] = array;
    }
    TonemapCurve tc = new TonemapCurve(newValues[TonemapCurve.CHANNEL_RED], newValues[TonemapCurve.CHANNEL_GREEN], newValues[TonemapCurve.CHANNEL_BLUE]);
    previewRequestBuilder.set(CaptureRequest.TONEMAP_MODE, CaptureRequest.TONEMAP_MODE_CONTRAST_CURVE);
    previewRequestBuilder.set(CaptureRequest.TONEMAP_CURVE, tc);
    applySettings();
}

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private void applySettings() {
    captureSession.setRepeatingRequest(previewRequestBuilder.build(), null, null);
}

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G仍在进行中。

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上面的代码示例可能不是 100% 正确，如果您有更好的解决方案或发现错误，请告诉我 ;)