小贝子编程

iOS 人脸检测器方向和 CIImage 方向设置



EDIT 找到了这段代码，它有助于前置摄像头图像 http://blog.logichigh.com/2008/06/05/uiimage-fix/

希望其他人有类似的问题，可以帮助我。还没有找到解决方案。(它可能看起来有点长，但只是一堆辅助代码)

我正在从相机(正面和背面)获取的图像以及来自图库的图像上使用ios面部检测器(我正在使用UIImagePicker- 用于相机捕获的图像和从图库中选择的图像 - 不使用avfoundation像方形摄像头演示那样拍照)

我弄乱了检测的坐标(如果有的话)，所以我写了一个简短的调试方法来获取人脸的边界以及一个在它们上面画一个正方形的实用程序，我想检查检测器工作的方向：

#define RECTBOX(R)   [NSValue valueWithCGRect:R]
- (NSArray *)detectFaces:(UIImage *)inputimage
{
_detector = [CIDetector detectorOfType:CIDetectorTypeFace context:nil options:[NSDictionary dictionaryWithObject:CIDetectorAccuracyLow forKey:CIDetectorAccuracy]];
NSNumber *orientation = [NSNumber numberWithInt:[inputimage imageOrientation]]; // i also saw code where they add +1 to the orientation
NSDictionary *imageOptions = [NSDictionary dictionaryWithObject:orientation forKey:CIDetectorImageOrientation];
CIImage* ciimage = [CIImage imageWithCGImage:inputimage.CGImage options:imageOptions];

// try like this first
//    NSArray* features = [self.detector featuresInImage:ciimage options:imageOptions];
// if not working go on to this (trying all orientations)
NSArray* features;
int exif;
// ios face detector. trying all of the orientations
for (exif = 1; exif <= 8 ; exif++)
{
NSNumber *orientation = [NSNumber numberWithInt:exif];
NSDictionary *imageOptions = [NSDictionary dictionaryWithObject:orientation forKey:CIDetectorImageOrientation];
NSTimeInterval start = [NSDate timeIntervalSinceReferenceDate];
features = [self.detector featuresInImage:ciimage options:imageOptions];
if (features.count > 0)
{
NSString *str = [NSString stringWithFormat:@"found faces using exif %d",exif];
[faceDetection log:str];
break;
}
NSTimeInterval duration = [NSDate timeIntervalSinceReferenceDate] - start;
NSLog(@"faceDetection: facedetection total runtime is %f s",duration);
}
if (features.count > 0)
{
[faceDetection log:@"-I- Found faces with ios face detector"];
for(CIFaceFeature *feature in features)
{
CGRect rect = feature.bounds;
CGRect r = CGRectMake(rect.origin.x,inputimage.size.height - rect.origin.y - rect.size.height,rect.size.width,rect.size.height);
[returnArray addObject:RECTBOX(r)];
}
return returnArray;
} else {
// no faces from iOS face detector. try OpenCV detector
}

[1]

在尝试了大量不同的图片后，我注意到人脸检测器的方向与相机图像属性不一致。我用前置摄像头拍了一堆照片 其中 uiimage 方向为 3(查询 imageOrienation)，但人脸检测器未找到该设置的人脸。当浏览所有 exif 可能性时，人脸检测器终于拾取了人脸，但方向不同。

！[1]： https://i.stack.imgur.com/D7bkZ.jpg

我该如何解决这个问题？我的代码有错误吗？

我遇到的另一个问题(但与人脸检测器密切相关)，当人脸检测器拾取人脸时，但对于"错误"的方向(主要发生在前置摄像头上)，最初使用的UIImage在 uiiimageview 中正确显示，但是当我绘制正方形叠加层时(我在我的应用程序中使用 opencv，所以我决定将UIImage转换为 cvmat 以使用 opencv 绘制叠加层)整个图像被旋转90 度(只有 cvmat 图像，而不是我最初显示的UIImage)

我能想到的原因是人脸检测器弄乱了UIimage转换为opencv mat正在使用的一些缓冲区(上下文？如何分离这些缓冲液？

将uiimage转换为cvmat的代码是(来自某人制作的"著名"UIImage类别)：

-(cv::Mat)CVMat
{
CGColorSpaceRef colorSpace = CGImageGetColorSpace(self.CGImage);
CGFloat cols = self.size.width;
CGFloat rows = self.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); // Bitmap info flags
CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), self.CGImage);
CGContextRelease(contextRef);
return cvMat;
}
- (id)initWithCVMat:(const cv::Mat&)cvMat
{
NSData *data = [NSData dataWithBytes:cvMat.data length:cvMat.elemSize() * cvMat.total()];
CGColorSpaceRef colorSpace;
if (cvMat.elemSize() == 1)
{
colorSpace = CGColorSpaceCreateDeviceGray();
}
else
{
colorSpace = CGColorSpaceCreateDeviceRGB();
}
CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef)data);
CGImageRef imageRef = CGImageCreate(cvMat.cols,                                     // Width
cvMat.rows,                                     // Height
8,                                              // Bits per component
8 * cvMat.elemSize(),                           // Bits per pixel
cvMat.step[0],                                  // Bytes per row
colorSpace,                                     // Colorspace
kCGImageAlphaNone | kCGBitmapByteOrderDefault,  // Bitmap info flags
provider,                                       // CGDataProviderRef
NULL,                                           // Decode
false,                                          // Should interpolate
kCGRenderingIntentDefault);                     // Intent   
self = [self initWithCGImage:imageRef];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpace);
return self;
}  
-(cv::Mat)CVRgbMat
{
cv::Mat tmpimage = self.CVMat;
cv::Mat image;
cvtColor(tmpimage, image, cv::COLOR_BGRA2BGR);
return image;
}
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)img editingInfo:(NSDictionary *)editInfo {
self.prevImage = img;
//   self.previewView.image = img;
NSArray *arr = [[faceDetection sharedFaceDetector] detectFaces:img];
for (id r in arr)
{
CGRect rect = RECTUNBOX(r);
//self.previewView.image = img;
self.previewView.image = [utils drawSquareOnImage:img square:rect];
}
[self.imgPicker dismissModalViewControllerAnimated:YES];
return;
}

我认为旋转整堆图像像素并匹配CIFaceFeature不是一个好主意。您可以想象在旋转方向上重绘是非常重的。我遇到了同样的问题，我通过转换 CIFaceFeature 相对于 UIImageOriented 的坐标系来解决它。我使用一些转换方法扩展了 CIFaceFeature 类，以获得与 UIImage 及其 UIImageView(或 UIView 的 CALayer)相关的正确点位置和边界。完整的实现发布在此处：https://gist.github.com/laoyang/5747004。您可以直接使用。

以下是 CIFaceFeature 中一个点的最基本转换，返回的 CGPoint 是根据图像的方向进行转换的：

- (CGPoint) pointForImage:(UIImage*) image fromPoint:(CGPoint) originalPoint {
CGFloat imageWidth = image.size.width;
CGFloat imageHeight = image.size.height;
CGPoint convertedPoint;
switch (image.imageOrientation) {
case UIImageOrientationUp:
convertedPoint.x = originalPoint.x;
convertedPoint.y = imageHeight - originalPoint.y;
break;
case UIImageOrientationDown:
convertedPoint.x = imageWidth - originalPoint.x;
convertedPoint.y = originalPoint.y;
break;
case UIImageOrientationLeft:
convertedPoint.x = imageWidth - originalPoint.y;
convertedPoint.y = imageHeight - originalPoint.x;
break;
case UIImageOrientationRight:
convertedPoint.x = originalPoint.y;
convertedPoint.y = originalPoint.x;
break;
case UIImageOrientationUpMirrored:
convertedPoint.x = imageWidth - originalPoint.x;
convertedPoint.y = imageHeight - originalPoint.y;
break;
case UIImageOrientationDownMirrored:
convertedPoint.x = originalPoint.x;
convertedPoint.y = originalPoint.y;
break;
case UIImageOrientationLeftMirrored:
convertedPoint.x = imageWidth - originalPoint.y;
convertedPoint.y = originalPoint.x;
break;
case UIImageOrientationRightMirrored:
convertedPoint.x = originalPoint.y;
convertedPoint.y = imageHeight - originalPoint.x;
break;
default:
break;
}
return convertedPoint;
}

以下是基于上述转换的类别方法：

// Get converted features with respect to the imageOrientation property
- (CGPoint) leftEyePositionForImage:(UIImage *)image;
- (CGPoint) rightEyePositionForImage:(UIImage *)image;
- (CGPoint) mouthPositionForImage:(UIImage *)image;
- (CGRect) boundsForImage:(UIImage *)image;
// Get normalized features (0-1) with respect to the imageOrientation property
- (CGPoint) normalizedLeftEyePositionForImage:(UIImage *)image;
- (CGPoint) normalizedRightEyePositionForImage:(UIImage *)image;
- (CGPoint) normalizedMouthPositionForImage:(UIImage *)image;
- (CGRect) normalizedBoundsForImage:(UIImage *)image;
// Get feature location inside of a given UIView size with respect to the imageOrientation property
- (CGPoint) leftEyePositionForImage:(UIImage *)image inView:(CGSize)viewSize;
- (CGPoint) rightEyePositionForImage:(UIImage *)image inView:(CGSize)viewSize;
- (CGPoint) mouthPositionForImage:(UIImage *)image inView:(CGSize)viewSize;
- (CGRect) boundsForImage:(UIImage *)image inView:(CGSize)viewSize;

(需要注意的另一件事是在从UIImage方向提取面部特征时指定正确的EXIF方向。相当令人困惑...这是我所做的：

int exifOrientation;
switch (self.image.imageOrientation) {
case UIImageOrientationUp:
exifOrientation = 1;
break;
case UIImageOrientationDown:
exifOrientation = 3;
break;
case UIImageOrientationLeft:
exifOrientation = 8;
break;
case UIImageOrientationRight:
exifOrientation = 6;
break;
case UIImageOrientationUpMirrored:
exifOrientation = 2;
break;
case UIImageOrientationDownMirrored:
exifOrientation = 4;
break;
case UIImageOrientationLeftMirrored:
exifOrientation = 5;
break;
case UIImageOrientationRightMirrored:
exifOrientation = 7;
break;
default:
break;
}
NSDictionary *detectorOptions = @{ CIDetectorAccuracy : CIDetectorAccuracyHigh };
CIDetector *faceDetector = [CIDetector detectorOfType:CIDetectorTypeFace context:nil options:detectorOptions];
NSArray *features = [faceDetector featuresInImage:[CIImage imageWithCGImage:self.image.CGImage]
options:@{CIDetectorImageOrientation:[NSNumber numberWithInt:exifOrientation]}];

)

iOS10 和 Swift 3

您可以检查苹果示例，您可以检测条形码和QR码的面部或值

https://developer.apple.com/library/content/samplecode/AVCamBarcode/Introduction/Intro.html

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