0

我想将 wxh 的 uint32_t 图像数据转换为 uint8_t 图像。我应该如何转换图像。我想将 leptonica 的 PIX 转换为 opencv Mat。

我想知道使用按位运算符的艰难方法。像素被打包为 AARRGGBB。

我也想转换

cv:Mat 8UC1 到 PIX。即8bit单通道图像到32bit图像。或者，如果您能想到任何其他方法来进行排序。

4

3 回答 3

1 
uint32_t * imData = yourImageDataPointer;
uchar * reinterpretedData = (uchar*)imData;

cv::Mat cvImage = cv::Mat(h,w, CV_8UC4);

cv::Mat bgr; // displayable image without alpha channel

cv::cvtColor(cvImage, bgr, CV_RGBA2BGR);

cv::imshow("img", bgr);
cv::waitKey (0);

如果不是您所期望的，请尝试此并发布结果图像

于 2016-05-14T07:32:19.983 回答
1

Here is the Answer to convert the cv::Mat to leptonicas 32bit PIX format:

PIX* toPIX(const cv::Mat& img)
{
    if(img.empty())
        throw std::invalid_argument("Image is empty");

    //PIX has got 4 channels hence we need to add one
    //more channel to this image
    cv::Mat alphaImage;
    if(img.type() == CV_8UC3) {
        cv::cvtColor(img,alphaImage,cv::COLOR_BGR2RGBA);
    } else if(img.type() == CV_8UC1) {
        cv::Mat gray = img.clone();
        std::vector<cv::Mat> channelsPlusAlpha;

        //construct 4 channel by reapeating gray across 3 channels and filling alpha with constant value
        channelsPlusAlpha.push_back(gray);//channels[2]);//R
        channelsPlusAlpha.push_back(gray);//channels[1]);//G
        channelsPlusAlpha.push_back(gray);//channels[0]);//B
        channelsPlusAlpha.push_back(cv::Mat(img.size(),CV_8UC1,cv::Scalar::all(255)));//A
        cv::merge(channelsPlusAlpha,alphaImage);
    } else {
        throw std::logic_error("Image type undefined");
    }


    //Prepare PIX
    int w = alphaImage.cols;
    int h = alphaImage.rows;
    int bpl = alphaImage.step1();//bytes per line
    int bpp = alphaImage.channels();//bytes per pixel
    int top = 0; //x (0,0) or if we want to deal with sub image then those coordinates have to be fed
    int left = 0;//y
    uchar* image_data = alphaImage.data;

    //Create PIX
    PIX *pix = pixCreate(w,h,32);
    uint32_t* data = pixGetData(pix);
    int wpl = pixGetWpl(pix);//get the words per line

    const uint8_t* imagedata = image_data + top * bpl + left * bpp;

    for(int y=0; y < h; ++y) {
        const uint8_t* linedata = imagedata; // linescan
        uint32_t* line = data + y *wpl;
        for(int x =0; x < w; ++x) {
            line[x] =   (linedata[0] << 24) |
                        (linedata[1] << 16) |
                        (linedata[2] << 8)  |
                        linedata[3];

            linedata += 4;
        }
        imagedata += bpl;
    }

    return pix;
}
于 2016-05-26T05:13:34.370 回答
1

如果您想使用您的数据获得 4 通道 RGBA 图像，您可以尝试将每个 uint32_t 转换为 4 个无符号字符数。有关如何执行此操作的讨论，请参阅将 int 转换为 4 字节 char 数组 (C) 。完成此操作后，您只需使用您获得的数据创建一个新cv::Mat的类型。CV_8UC4

于 2016-05-13T12:59:44.667 回答