[英]Convert image to black and white (not grayscale) using OpenCV iOS Objective C
我在SO上經歷了許多類似的問題,但是沒有給出我需要的特定輸出。 我曾嘗試將圖像轉換為黑白圖像,但由於某些原因,某些文本顯示不清晰或可以說會變形。 下面是到目前為止我嘗試過的代碼...
+(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; }
我從上面的代碼中獲得的輸出在這里 ,而我想要的結果在這里 ,任何幫助都會很棒..! 謝謝
編輯 :-原始圖像在這里
我想回答我的問題,因為我可能會有所幫助。 通過更改自適應閾值算法和塊大小的值,獲得了黑白輸出,下面是使用的代碼
+(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;
}
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