Base Classes for Post-processing Plugins

A model postprocessing plugin is used to postprocess the output tensor of model inference and write the corresponding result to the metadata. The input and output types required for postprocessing of different inference job types are different. Therefore, different postprocessing plugins are required. To facilitate reuse, MindX SDK has extracted some APIs and members to the postprocessing base class. For each type of job, such as the object detection job, the postprocessing .so file is dynamically loaded to support polymorphism of various models (such as YOLOv3, Faster R-CNN, and SsdVgg-16).

Function	Performs postprocessing on the output tensor of model inference.
Constraints	The postprocessing plugins can be used after being connected to the mxpi_tensorinfer inference plugin. Only MxpiTensorPackageList can be used as the metadata input. The parent class does not generate plugins, and the child class inherits the plugins generated by the parent class.
Parent Class	MxModelPostProcessorBase and MxImagePostProcessorBase (image postprocessing base class, inherited from MxModelPostProcessorBase)
Input/Output	Input: buffer (data type: MxpiBuffer) and metadata (data type: MxpiTensorPackageList) Output: buffer (data type: MxpiBuffer) and metadata (data type: MxpiObjectList, MxpiClassList, MxpiImageMaskList, or MxpiTextObjectList)
Port Format (Caps)	Static input: {"metadata/tensor"} Static output: subclass overriding
Property	For details, see Table 1.

**Table 1** Properties of MxModelPostProcessorBase and MxImagePostProcessorBase
Property Name	Description	Mandatory or Not	Modifiable or Not
deviceId	Ascend device ID, which is specified by the deviceId property in the stream_config field. You do not need to set the ID.	No	Yes
postProcessLibPath	Path of the .so file of the postprocessing DLL. If this property is not specified, the model inference result is directly written to the metadata MxpiTensorPackageList and output to the position specified by outputDeviceId.	Yes	Yes
labelPath	Path of the postprocessing class label	No	Yes
dataSource	Index of the input data (generally the name of the upstream element). The default value is the key value of the output port of the upstream plugin.	No	Yes
postProcessConfigPath	Path of the postprocessing configuration file	Generally required	Yes
postProcessConfigContent	Post-processing configuration	No	Yes
dataSourceResize	This property is available only in the subclass plugins that inherit MxImagePostProcessorBase (image postprocessing base class). Whether to map the coordinates in the postprocessing of the model back to the image before scaling. If this property is not set, the value is obtained from the previous plugin of the inference plugin by default. If the value cannot be obtained, the coordinates are not scaled.	No	Yes
dataSourceRoiBoxes	This property is available only in the subclass plugins that inherit MxImagePostProcessorBase (image postprocessing base class). Specifies whether to map the coordinates of the model inference to the source image before cropping. If this property is not set, the image is not mapped to the source image by default. To map the image, set the property to the name of the image cropping plugin.	No	Yes
dataSourceImage	It is under internal debugging. Do not use it.	No	No

**Table 2** Python postprocessing properties
Property Name	Description	Mandatory or Not	Modifiable or Not
funcLanguage	Development language of the postprocessing plugin, that is, C++ or Python	No	Yes
postProcessLibPath	Directory of the postprocessing DLL SO file. This directory contains the postprocessing Python file or SO file	Yes	Yes
className	Post-processing class name	Yes	Yes
pythonModule	Name of the loaded postprocessing module, which is the same as the module name in Python or SO file	Yes	Yes
labelPath	Path of the postprocessing class label	No	Yes
dataSource	Index of the input data (generally the name of the upstream element)	Recommended	Yes
postProcessConfigPath	Path of the postprocessing configuration file	Generally required	Yes
deviceId	Ascend device ID, which is specified by the deviceId property in the stream_config field. You do not need to set the ID.	No	Yes
dataSourceResize	This property is available only in the subclass plugins that inherit MxImagePostProcessorBase (image postprocessing base class). Whether to map the coordinates in the postprocessing of the model back to the image before scaling. If this property is not set, the value is obtained from the previous plugin of the inference plugin by default. If the value cannot be obtained, the coordinates are not scaled.	No	Yes
dataSourceRoiBoxes	This property is available only in the subclass plugins that inherit MxImagePostProcessorBase (image postprocessing base class). Specifies whether to map the coordinates of the model inference to the source image before cropping. If this property is not set, the image is not mapped to the source image by default. To map the image, set the property to the name of the image cropping plugin.	No	Yes

Figure 1 Inheritance relationship of postprocessing plugin classes

Parent topic: Model Post-processing Plugins