setPreferableBackend和setPreferableTarget

setPreferableBackend和setPreferableTarget

1. 环境
   opencv4.4.0
2. setPreferableBackend()函数原型

/**
 * @brief Ask network to use specific computation backend where it supported.
 * @param[in] backendId backend identifier.
 * @see Backend
 *
 * If OpenCV is compiled with Intel's Inference Engine library, DNN_BACKEND_DEFAULT
 * means DNN_BACKEND_INFERENCE_ENGINE. Otherwise it equals to DNN_BACKEND_OPENCV.
 */
CV_WRAP void setPreferableBackend(int backendId);

3. setPreferableTarget()函数原型

/**
 * @brief Ask network to make computations on specific target device.
 * @param[in] targetId target identifier.
 * @see Target
 *
 * List of supported combinations backend / target:
 * |                        | DNN_BACKEND_OPENCV | DNN_BACKEND_INFERENCE_ENGINE | DNN_BACKEND_HALIDE |  DNN_BACKEND_CUDA |
 * |------------------------|--------------------|------------------------------|--------------------|-------------------|
 * | DNN_TARGET_CPU         |                  + |                            + |                  + |                   |
 * | DNN_TARGET_OPENCL      |