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Exposure Auto#

相机的 Exposure Auto 功能会自动在指定限值内调整曝光时间,直到达到目标亮度为止。

自动功能的像素数据可以来自一个或多个自动功能 ROI

如果要同时使用 Exposure Auto 和 Gain Auto,使用 Auto Function Profile 功能可以指定如何平衡两者效果。

要手动调整曝光时间,请使用 Exposure Time 功能。

该功能的使用#

启用或禁用 Exposure Auto#

要启用或禁用 Exposure Auto 自动功能:

  1. 至少一个自动功能 ROI 分配给 Exposure Auto 自动功能。
    确保自动功能 ROI 部分或完全与图像 ROI 重叠。
  2. ExposureMode 参数设置为 Timed
  3. 设置 ExposureAuto 参数设置为以下工作模式之一:
    • Once:相机调整曝光时间,直至达到指定的目标亮度值。完成此操作后,或最多经过 30 个计算周期后,相机会将自动功能设置为 Off。相机会将以下计算得出的曝光时间应用于所有后续图像。
    • Continuous:相机在采集图像时连续调整曝光时间。
    • Off:禁用 Exposure Auto 功能。曝光时间保持为上次自动或手动调整后的值。

信息

当相机连续拍摄图像时,自动功能会在经过较短的延迟后生效。前几张图像可能不受自动功能的影响。

指定下限和上限#

自动功能会在您指定的限值范围内调整 ExposureTime 参数值。

要更改限值,请将 AutoExposureTimeLowerLimitAutoExposureTimeUpperLimit 参数设置为所需值(单位为 µs)。

示例:假设您已将 AutoExposureTimeLowerLimit 参数设置为 1000,并将 AutoExposureTimeUpperLimit 参数设置为 5000。在自动调节过程中,曝光时间将永远不会低于 1000 µs 且不会高于 5000 µs。

如果将 AutoExposureTimeUpperLimit 参数设置为较高的值,则相机的帧速率可能会降低。

指定目标亮度值#

自动功能会调整曝光时间,直至达到目标亮度值(即平均灰度值)为止。

要指定目标值,请使用 AutoTargetBrightness 参数。

信息

  • 目标值计算不包括其他图像优化,例如 Gamma。根据设置的图像优化,相机输出的图像平均灰度值可能会明显低于或高于目标值。
  • 相机还使用 AutoTargetBrightness 参数来控制自动功能 Gain Auto。如果要同时使用 Exposure Auto 和 Gain Auto,使用 Auto Function Profile 功能可以指定如何平衡两者效果。
  • 在部分相机机型上,您可以使用 Remove Parameter Limits 功能提高目标值参数的上限。

在 Basler ace GigE 相机型号上,您还可以指定一个 Gray Value Adjustment Damping 系数。在 Basler dart 和 pulse 相机型号上,您可以指定 Brightness Adjustment Damping 系数。

如果使用阻尼系数,则达到目标值的速度会更慢。

示例代码#

ace Classic/U/L GigE 相机#

// Set the Exposure Auto auto function to its minimum lower limit
// and its maximum upper limit
double minLowerLimit = camera.AutoExposureTimeLowerLimitRaw.GetMin();
double maxUpperLimit = camera.AutoExposureTimeUpperLimitRaw.GetMax();
camera.AutoExposureTimeLowerLimitRaw.SetValue(minLowerLimit);
camera.AutoExposureTimeUpperLimitRaw.SetValue(maxUpperLimit);
// Set the target brightness value to 128
camera.AutoTargetValue.SetValue(128);
// Select auto function ROI 1
camera.AutoFunctionAOISelector.SetValue(AutoFunctionAOISelector_AOI1);
// Enable the 'Intensity' auto function (Gain Auto + Exposure Auto)
// for the auto function ROI selected
camera.AutoFunctionAOIUsageIntensity.SetValue(true);
// Enable Exposure Auto by setting the operating mode to Continuous
camera.ExposureAuto.SetValue(ExposureAuto_Continuous);
INodeMap& nodemap = camera.GetNodeMap();
// Set the Exposure Auto auto function to its minimum lower limit
// and its maximum upper limit
double minLowerLimit = CFloatParameter(nodemap, "AutoExposureTimeLowerLimitRaw").GetMin();
double maxUpperLimit = CFloatParameter(nodemap, "AutoExposureTimeUpperLimitRaw").GetMax();
CFloatParameter(nodemap, "AutoExposureTimeLowerLimitRaw").SetValue(minLowerLimit);
CFloatParameter(nodemap, "AutoExposureTimeUpperLimitRaw").SetValue(maxUpperLimit);
// Set the target brightness value to 128
CIntegerParameter(nodemap, "AutoTargetValue").SetValue(128);
// Select auto function ROI 1
CEnumParameter(nodemap, "AutoFunctionAOISelector").SetValue("AOI1");
// Enable the 'Intensity' auto function (Gain Auto + Exposure Auto)
// for the auto function ROI selected
CBooleanParameter(nodemap, "AutoFunctionAOIUsageIntensity").SetValue(true);
// Enable Exposure Auto by setting the operating mode to Continuous
CEnumParameter(nodemap, "ExposureAuto").SetValue("Continuous");
// Set the Exposure Auto auto function to its minimum lower limit
// and its maximum upper limit
double minLowerLimit = camera.Parameters[PLCamera.AutoExposureTimeLowerLimitRaw].GetMinimum();
double maxUpperLimit = camera.Parameters[PLCamera.AutoExposureTimeUpperLimitRaw].GetMaximum();
camera.Parameters[PLCamera.AutoExposureTimeLowerLimitRaw].SetValue(minLowerLimit);
camera.Parameters[PLCamera.AutoExposureTimeUpperLimitRaw].SetValue(maxUpperLimit);
// Set the target brightness value to 128
camera.Parameters[PLCamera.AutoTargetValue].SetValue(128);
// Select auto function ROI 1
camera.Parameters[PLCamera.AutoFunctionAOISelector].SetValue(PLCamera.AutoFunctionAOISelector.AOI1);
// Enable the 'Intensity' auto function (Gain Auto + Exposure Auto)
// for the auto function ROI selected
camera.Parameters[PLCamera.AutoFunctionAOIUsageIntensity].SetValue(true);
// Enable Exposure Auto by setting the operating mode to Continuous
camera.Parameters[PLCamera.ExposureAuto].SetValue(PLCamera.ExposureAuto.Continuous);
/* Macro to check for errors */
#define CHECK(errc) if (GENAPI_E_OK != errc) printErrorAndExit(errc)
GENAPIC_RESULT errRes = GENAPI_E_OK;  /* Return value of pylon methods */
double minLowerLimit = 0;
double maxUpperLimit = 0;
/* Set the Exposure Auto auto function to its minimum lower limit */
/* and its maximum upper limit */
errRes = PylonDeviceGetFloatFeatureMin(hdev, "AutoExposureTimeLowerLimitRaw", &minLowerLimit);
CHECK(errRes);
errRes = PylonDeviceGetFloatFeatureMax(hdev, "AutoExposureTimeUpperLimitRaw", &maxUpperLimit);
CHECK(errRes);
errRes = PylonDeviceSetFloatFeature(hdev, "AutoExposureTimeLowerLimitRaw", minLowerLimit);
CHECK(errRes);
errRes = PylonDeviceSetFloatFeature(hdev, "AutoExposureTimeUpperLimitRaw", maxUpperLimit);
CHECK(errRes);
/* Set the target brightness value to 128 */
errRes = PylonDeviceSetIntegerFeature(hdev, "AutoTargetValue", 128);
CHECK(errRes);
/* Select auto function ROI 1 */
errRes = PylonDeviceFeatureFromString(hdev, "AutoFunctionAOISelector", "AOI1");
CHECK(errRes);
/* Enable the 'Intensity' auto function (Gain Auto + Exposure Auto) */
/* for the auto function ROI selected */
errRes = PylonDeviceSetBooleanFeature(hdev, "AutoFunctionAOIUsageIntensity", 1);
CHECK(errRes);
/* Enable Exposure Auto by setting the operating mode to Continuous */
errRes = PylonDeviceFeatureFromString(hdev, "ExposureAuto", "Continuous");
CHECK(errRes);

其他相机#

// Set the  Exposure Auto auto function to its minimum lower limit
// and its maximum upper limit
double minLowerLimit = camera.AutoExposureTimeLowerLimit.GetMin();
double maxUpperLimit = camera.AutoExposureTimeUpperLimit.GetMax();
camera.AutoExposureTimeLowerLimit.SetValue(minLowerLimit);
camera.AutoExposureTimeUpperLimit.SetValue(maxUpperLimit);
// Set the target brightness value to 0.6
camera.AutoTargetBrightness.SetValue(0.6);
// Select auto function ROI 1
camera.AutoFunctionROISelector.SetValue(AutoFunctionROISelector_ROI1);
// Enable the 'Brightness' auto function (Gain Auto + Exposure Auto)
// for the auto function ROI selected
camera.AutoFunctionROIUseBrightness.SetValue(true);
// Enable Exposure Auto by setting the operating mode to Continuous
camera.ExposureAuto.SetValue(ExposureAuto_Continuous);
INodeMap& nodemap = camera.GetNodeMap();
// Set the  Exposure Auto auto function to its minimum lower limit
// and its maximum upper limit
double minLowerLimit = CFloatParameter(nodemap, "AutoExposureTimeLowerLimit").GetMin();
double maxUpperLimit = CFloatParameter(nodemap, "AutoExposureTimeUpperLimit").GetMax();
CFloatParameter(nodemap, "AutoExposureTimeLowerLimit").SetValue(minLowerLimit);
CFloatParameter(nodemap, "AutoExposureTimeUpperLimit").SetValue(maxUpperLimit);
// Set the target brightness value to 0.6
CFloatParameter(nodemap, "AutoTargetBrightness").SetValue(0.6);
// Select auto function ROI 1
CEnumParameter(nodemap, "AutoFunctionROISelector").SetValue("ROI1");
// Enable the 'Brightness' auto function (Gain Auto + Exposure Auto)
// for the auto function ROI selected
CBooleanParameter(nodemap, "AutoFunctionROIUseBrightness").SetValue(true);
// Enable Exposure Auto by setting the operating mode to Continuous
CEnumParameter(nodemap, "ExposureAuto").SetValue("Continuous");
// Set the  Exposure Auto auto function to its minimum lower limit
// and its maximum upper limit
double minLowerLimit = camera.Parameters[PLCamera.AutoExposureTimeLowerLimit].GetMinimum();
double maxUpperLimit = camera.Parameters[PLCamera.AutoExposureTimeUpperLimit].GetMaximum();
camera.Parameters[PLCamera.AutoExposureTimeLowerLimit].SetValue(minLowerLimit);
camera.Parameters[PLCamera.AutoExposureTimeUpperLimit].SetValue(maxUpperLimit);
// Set the target brightness value to 0.6
camera.Parameters[PLCamera.AutoTargetBrightness].SetValue(0.6);
// Select auto function ROI 1
camera.Parameters[PLCamera.AutoFunctionROISelector].SetValue(PLCamera.AutoFunctionROISelector.ROI1);
// Enable the 'Brightness' auto function (Gain Auto + Exposure Auto)
// for the auto function ROI selected
camera.Parameters[PLCamera.AutoFunctionROIUseBrightness].SetValue(true);
// Enable Exposure Auto by setting the operating mode to Continuous
camera.Parameters[PLCamera.ExposureAuto].SetValue(PLCamera.ExposureAuto.Continuous);
/* Macro to check for errors */
#define CHECK(errc) if (GENAPI_E_OK != errc) printErrorAndExit(errc)
GENAPIC_RESULT errRes = GENAPI_E_OK;  /* Return value of pylon methods */
double minLowerLimit = 0;
double maxUpperLimit = 0;
/* Set the  Exposure Auto auto function to its minimum lower limit */
/* and its maximum upper limit */
errRes = PylonDeviceGetFloatFeatureMin(hdev, "AutoExposureTimeLowerLimit", &minLowerLimit);
CHECK(errRes);
errRes = PylonDeviceGetFloatFeatureMax(hdev, "AutoExposureTimeUpperLimit", &maxUpperLimit);
CHECK(errRes);
errRes = PylonDeviceSetFloatFeature(hdev, "AutoExposureTimeLowerLimit", minLowerLimit);
CHECK(errRes);
errRes = PylonDeviceSetFloatFeature(hdev, "AutoExposureTimeUpperLimit", maxUpperLimit);
CHECK(errRes);
/* Set the target brightness value to 0.6 */
errRes = PylonDeviceSetFloatFeature(hdev, "AutoTargetBrightness", 0.6);
CHECK(errRes);
/* Select auto function ROI 1 */
errRes = PylonDeviceFeatureFromString(hdev, "AutoFunctionROISelector", "ROI1");
CHECK(errRes);
/* Enable the 'Brightness' auto function (Gain Auto + Exposure Auto) */
/* for the auto function ROI selected */
errRes = PylonDeviceSetBooleanFeature(hdev, "AutoFunctionROIUseBrightness", 1);
CHECK(errRes);
/* Enable Exposure Auto by setting the operating mode to Continuous */
errRes = PylonDeviceFeatureFromString(hdev, "ExposureAuto", "Continuous");
CHECK(errRes);

您也可以使用 pylon Viewer 轻松设置参数。