Question

我在SO上经历过许多类似的问题，但它没有给出我需要的具体输出。我曾尝试将图像转换为黑白图像，但由于某种原因，某些文字看起来不清晰，或者我们可以说是扭曲了。下面是我到目前为止尝试过的代码......

   +(UIImage *)grayImage:(UIImage *)processedImage{

        cv::Mat grayImage = [MMOpenCVHelper cvMatGrayFromAdjustedUIImage:processedImage];

        cv::adaptiveThreshold(grayImage, grayImage, 255, cv::ADAPTIVE_THRESH_GAUSSIAN_C, cv::THRESH_BINARY, 11, 2);

        cv::GaussianBlur(grayImage, grayImage, cv::Size(1,1), 50.0);

        UIImage *grayeditImage=[MMOpenCVHelper UIImageFromCVMat:grayImage];
        grayImage.release();

        return grayeditImage;

    }

+ (cv::Mat)cvMatGrayFromAdjustedUIImage:(UIImage *)image {
    cv::Mat cvMat = [self cvMatFromAdjustedUIImage:image];
    cv::Mat grayMat;
    if ( cvMat.channels() == 1 ) {
        grayMat = cvMat;
    }
    else {
        grayMat = cv :: Mat( cvMat.rows,cvMat.cols, CV_8UC1 );
        cv::cvtColor( cvMat, grayMat, cv::COLOR_BGR2GRAY );
    }
    return grayMat; }

+ (cv::Mat)cvMatFromAdjustedUIImage:(UIImage *)image {
    CGColorSpaceRef colorSpace = CGImageGetColorSpace(image.CGImage);
    CGFloat cols = image.size.width;
    CGFloat rows = image.size.height;

    cv::Mat cvMat(rows, cols, CV_8UC4); // 8 bits per component, 4 channels

    CGContextRef contextRef = CGBitmapContextCreate(cvMat.data,                 // Pointer to backing data
                                                    cols,                       // Width of bitmap
                                                    rows,                       // Height of bitmap
                                                    8,                          // Bits per component
                                                    cvMat.step[0],              // Bytes per row
                                                    colorSpace,                 // Colorspace
                                                    kCGImageAlphaNoneSkipLast |
                                                    kCGBitmapByteOrderDefault);

    CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), image.CGImage);
    CGContextRelease(contextRef);
    return cvMat; }

+ (UIImage *)UIImageFromCVMat:(cv::Mat)cvMat {
    NSData *data = [NSData dataWithBytes:cvMat.data length:cvMat.elemSize()*cvMat.total()];
    CGColorSpaceRef colorSpace;
    CGBitmapInfo bitmapInfo;

    if (cvMat.elemSize() == 1) {
        colorSpace = CGColorSpaceCreateDeviceGray();
        bitmapInfo = kCGImageAlphaNone | kCGBitmapByteOrderDefault;

    } else {
        colorSpace = CGColorSpaceCreateDeviceRGB();
        bitmapInfo = kCGBitmapByteOrder32Little | (
                                                   cvMat.elemSize() == 3? kCGImageAlphaNone : kCGImageAlphaNoneSkipFirst
                                                   );
    }

    CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef)data);

    // Creating CGImage from cv::Mat
    CGImageRef imageRef = CGImageCreate(cvMat.cols,                                 //width
                                        cvMat.rows,                                 //height
                                        8,                                          //bits per component
                                        8 * cvMat.elemSize(),                       //bits per pixel
                                        cvMat.step[0],                            //bytesPerRow
                                        colorSpace,                                 //colorspace
                                        bitmapInfo,// bitmap info
                                        provider,                                   //CGDataProviderRef
                                        NULL,                                       //decode
                                        false,                                      //should interpolate
                                        kCGRenderingIntentDefault                   //intent
                                        );



    // Getting UIImage from CGImage
    UIImage *finalImage = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);
    CGDataProviderRelease(provider);
    CGColorSpaceRelease(colorSpace);
    return finalImage; }

我从上面代码得到的输出是here，我想要的结果是here，任何帮助都会很棒..！谢谢

已编辑： - 原始图片here

Answer 1

我想回答我的问题，因为我可能会有所帮助。我通过改变自适应阈值算法和块大小值来获得B / W输出，下面是使用的代码

    +(UIImage *)grayImage:(UIImage *)processedImage{ // B/W

    cv::Mat grayImage = [MMOpenCVHelper cvMatGrayFromAdjustedUIImage:processedImage];
    cv::adaptiveThreshold(grayImage, grayImage, 255, cv::ADAPTIVE_THRESH_MEAN_C, cv::THRESH_BINARY, 11, 7);
    cv::GaussianBlur(grayImage, grayImage, cv::Size(1,1), 50.0);

    UIImage *grayeditImage=[MMOpenCVHelper UIImageFromCVMat:grayImage];
    grayImage.release();

    return grayeditImage;
}

使用OpenCV iOS Objective C将图像转换为黑白（不是灰度）

1 个答案: