android - camera2 像素值与传感器曝光时间不成线性关系

Question

我尝试使用使用 YUV_420_888 图像格式的 camera2 API 近似原始传感器输出(我的索尼 XA1 不支持原始传感器)。我将所有内容都手动并停用了我能找到的每个更正程序:

            mBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_OFF);
            mBuilder.set(CaptureRequest.CONTROL_AF_MODE, CameraMetadata.CONTROL_AF_MODE_OFF);
            mBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraMetadata.CONTROL_AE_MODE_OFF);
            mBuilder.set(CaptureRequest.CONTROL_AWB_MODE, CameraMetadata.CONTROL_AWB_MODE_OFF);
            mBuilder.set(CaptureRequest.TONEMAP_MODE, CameraMetadata.TONEMAP_MODE_CONTRAST_CURVE);
            mBuilder.set(CaptureRequest.TONEMAP_CURVE,
                    new TonemapCurve(
                            new float[]{0.0f,0.0f,1.0f,1.0f},
                            new float[]{0.0f,0.0f,1.0f,1.0f},
                            new float[]{0.0f,0.0f,1.0f,1.0f}
                    ));
            mBuilder.set(CaptureRequest.COLOR_CORRECTION_MODE, CameraMetadata.COLOR_CORRECTION_MODE_TRANSFORM_MATRIX);
            mBuilder.set(CaptureRequest.COLOR_CORRECTION_TRANSFORM, new ColorSpaceTransform(new int[]{
                    1, 1, 0, 1, 0, 1,
                    0, 1, 1, 1, 0, 1,
                    0, 1, 0, 1, 1, 1
            }));
            mBuilder.set(CaptureRequest.COLOR_CORRECTION_GAINS, new RggbChannelVector(1.0f,1.0f,1.0f,1.0f));
            mBuilder.set(CaptureRequest.SHADING_MODE, CameraMetadata.SHADING_MODE_OFF);
            mBuilder.set(CaptureRequest.STATISTICS_LENS_SHADING_MAP_MODE, CameraMetadata.STATISTICS_LENS_SHADING_MAP_MODE_OFF);
            mBuilder.set(CaptureRequest.COLOR_CORRECTION_ABERRATION_MODE, CameraMetadata.COLOR_CORRECTION_ABERRATION_MODE_OFF);
            mBuilder.set(CaptureRequest.CONTROL_AE_ANTIBANDING_MODE, CameraMetadata.CONTROL_AE_ANTIBANDING_MODE_OFF);
            mBuilder.set(CaptureRequest.CONTROL_EFFECT_MODE, CameraMetadata.CONTROL_EFFECT_MODE_OFF);
            mBuilder.set(CaptureRequest.CONTROL_ENABLE_ZSL, false);
            mBuilder.set(CaptureRequest.CONTROL_SCENE_MODE, CameraMetadata.CONTROL_SCENE_MODE_DISABLED);
            mBuilder.set(CaptureRequest.EDGE_MODE, CameraMetadata.EDGE_MODE_OFF);
            mBuilder.set(CaptureRequest.HOT_PIXEL_MODE, CameraMetadata.HOT_PIXEL_MODE_OFF);
            mBuilder.set(CaptureRequest.NOISE_REDUCTION_MODE, CameraMetadata.NOISE_REDUCTION_MODE_OFF);

在那之后，我连拍了 10 张照片，曝光时间线性增加，ISO 为 40。我分析了 Y 层(亮度分量)的值，发现它们的线性度最高只有 203(8 位满范围 = 255)。与 Gamma 校正曲线不同，203 处的过渡非常尖锐。
问题:
这是物理传感器效应，即像素饱和吗？
我是否忘记了管道中的一些非线性校正？
camera2 API 是否对 YUV_420_888 使用全范围线性变换？
谢谢你的帮助!

Answer 1

测试了不同的 ISO 值 (100,400)，非线性仍然存在。这不包括传感器的物理饱和。
但后来我测试了 RGB 值，它们是线性的。有问题的 Y 值 >203 转换到 RGB [0,255] 范围之外。问题解决了，但是改造需要很多时间。