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55 lines
1.5 KiB
C++
55 lines
1.5 KiB
C++
#include <opencv2/imgcodecs.hpp>
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using namespace cv;
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using namespace std;
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static void paintAlphaMat(Mat &mat)
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{
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CV_Assert(mat.channels() == 4);
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for (int i = 0; i < mat.rows; ++i)
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{
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for (int j = 0; j < mat.cols; ++j)
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{
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Vec4b& bgra = mat.at<Vec4b>(i, j);
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bgra[0] = UCHAR_MAX; // Blue
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bgra[1] = saturate_cast<uchar>((float (mat.cols - j)) / ((float)mat.cols) * UCHAR_MAX); // Green
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bgra[2] = saturate_cast<uchar>((float (mat.rows - i)) / ((float)mat.rows) * UCHAR_MAX); // Red
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bgra[3] = saturate_cast<uchar>(0.5 * (bgra[1] + bgra[2])); // Alpha
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}
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}
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}
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int main()
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{
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Mat mat(480, 640, CV_8UC4); // Create a matrix with alpha channel
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paintAlphaMat(mat);
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vector<int> compression_params;
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compression_params.push_back(IMWRITE_PNG_COMPRESSION);
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compression_params.push_back(9);
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bool result = false;
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try
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{
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result = imwrite("alpha.png", mat, compression_params);
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}
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catch (const cv::Exception& ex)
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{
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fprintf(stderr, "Exception converting image to PNG format: %s\n", ex.what());
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}
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if (result)
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printf("Saved PNG file with alpha data.\n");
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else
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printf("ERROR: Can't save PNG file.\n");
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vector<Mat> imgs;
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imgs.push_back(mat);
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imgs.push_back(~mat);
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imgs.push_back(mat(Rect(0, 0, mat.cols / 2, mat.rows / 2)));
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imwrite("test.tiff", imgs);
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printf("Multiple files saved in test.tiff\n");
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return result ? 0 : 1;
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}
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