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

Question

我在SO上经历了许多类似的问题，但它没有给出我需要的特定输出。我尝试将图像转换为黑白，但由于某种原因，某些文本看起来不清晰，或者我们可以说失真了。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; }

我从上面的代码中获得的输出在这里，我想要的结果在这里，任何帮助都会很棒..！谢谢

已编辑：- 原始图片在这里

Answer 1

我想回答我的问题，因为我可能会有所帮助。我通过更改自适应阈值算法和块大小值获得了黑白输出，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;
}