ocv_common.hpp

// Copyright (C) 2018-2019 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
//

/**
 * @brief a header file with common samples functionality using OpenCV
 * @file ocv_common.hpp
 */

#pragma once

#include <common.hpp>
#include <opencv2/opencv.hpp>

/**
* @brief Sets image data stored in cv::Mat object to a given Blob object.
* @param orig_image - given cv::Mat object with an image data.
* @param blob - Blob object which to be filled by an image data.
* @param batchIndex - batch index of an image inside of the blob.
*/
template <typename T>
void matU8ToBlob(const cv::Mat& orig_image, InferenceEngine::Blob::Ptr& blob, int batchIndex = 0) {
    InferenceEngine::SizeVector blobSize = blob->getTensorDesc().getDims();
    const size_t width = blobSize[3];
    const size_t height = blobSize[2];
    const size_t channels = blobSize[1];
    T* blob_data = blob->buffer().as<T*>();

    cv::Mat resized_image(orig_image);
    if (static_cast<int>(width) != orig_image.size().width ||
            static_cast<int>(height) != orig_image.size().height) {
        cv::resize(orig_image, resized_image, cv::Size(width, height));
    }

    int batchOffset = batchIndex * width * height * channels;

    if (channels == 1) {
        for (size_t  h = 0; h < height; h++) {
            for (size_t w = 0; w < width; w++) {
                blob_data[batchOffset + h * width + w] = resized_image.at<uchar>(h, w);
            }
        }
    } else if (channels == 3) {
        for (size_t c = 0; c < channels; c++) {
            for (size_t  h = 0; h < height; h++) {
                for (size_t w = 0; w < width; w++) {
                    blob_data[batchOffset + c * width * height + h * width + w] =
                            resized_image.at<cv::Vec3b>(h, w)[c];
                }
            }
        }
    } else {
        THROW_IE_EXCEPTION << "Unsupported number of channels";
    }
}

/**
 * @brief Wraps data stored inside of a passed cv::Mat object by new Blob pointer.
 * @note: No memory allocation is happened. The blob just points to already existing
 *        cv::Mat data.
 * @param mat - given cv::Mat object with an image data.
 * @return resulting Blob pointer.
 */
static UNUSED InferenceEngine::Blob::Ptr wrapMat2Blob(const cv::Mat &mat) {
    size_t channels = mat.channels();
    size_t height = mat.size().height;
    size_t width = mat.size().width;

    size_t strideH = mat.step.buf[0];
    size_t strideW = mat.step.buf[1];

    bool is_dense =
            strideW == channels &&
            strideH == channels * width;

    if (!is_dense) THROW_IE_EXCEPTION
                << "Doesn't support conversion from not dense cv::Mat";

    InferenceEngine::TensorDesc tDesc(InferenceEngine::Precision::U8,
                                      {1, channels, height, width},
                                      InferenceEngine::Layout::NHWC);

    return InferenceEngine::make_shared_blob<uint8_t>(tDesc, mat.data);
}