（忽略下面的大量代码块。它只是供参考/资源，以防其他人想一起玩）
CoreImage 中的人脸检测例程自然在较小的图像上工作得更快，所以我一直在研究使用 来生成人aspectRatioThumbnail脸数据，并计划将其放大以利用fullScreenImage表示。我这样做的原因是我可能要处理 20-30 张图像，所以我想减少任务时间。
这可能是一个简单的数学问题，但我试图将一个图像中的点映射到另一个图像时得到不准确的结果。
90 x 120 图像 - CGPoint(64, 50) rightEyePosition
至
480 x 640 图像 - CGPoint(331, 303) rightEyePosition
(480 /90) * 64 = 341.333 - 但应该是 331，是吗？我做错了吗？
更新- 稍后再进行一些测试。那么也许只是因为图像分辨率不同，人脸数据结果略有不同？这是有道理的：数据结果之间没有可扩展的关系。不过我仍然想知道：我上面的缩放数学是错误的吗？
Using CIDetectorAccuracyHigh
useImageOptions: 0
------------ aspectRatioThumbnail 90.000000 120.000000 orientation: 0
2013-01-18 12:33:30.378 SeqMeTestBed[9705:907] aspectRatioThumbnail: features {
bounds = "{{23, 16}, {56, 56}}";
hasLeftEyePosition = 1;
hasMouthPosition = 1;
hasRightEyePosition = 1;
leftEyePosition = "{43, 59}";
mouthPosition = "{51, 31}";
rightEyePosition = "{64, 50}";
}
------------ fullScreenImage 480.000000 640.000000 orientation: 0
2013-01-18 12:33:33.029 SeqMeTestBed[9705:907] fullScreenImage: features {
bounds = "{{135, 81}, {298, 298}}";
hasLeftEyePosition = 1;
hasMouthPosition = 1;
hasRightEyePosition = 1;
leftEyePosition = "{228, 321}";
mouthPosition = "{290, 156}";
rightEyePosition = "{331, 303}";
}
------------ fullResolutionImage 640.000000 480.000000 orientation: 0
2013-01-18 12:33:35.745 SeqMeTestBed[9705:907] fullResolutionImage: features {
bounds = "{{195, 105}, {366, 366}}";
hasLeftEyePosition = 1;
hasMouthPosition = 1;
hasRightEyePosition = 1;
leftEyePosition = "{356, 411}";
mouthPosition = "{350, 201}";
rightEyePosition = "{455, 400}";
// 使用的代码 //
- (void)detectFacialFeatures
{
NSDictionary *detectorOptions = [[NSDictionary alloc] initWithObjectsAndKeys:CIDetectorAccuracyHigh, CIDetectorAccuracy, nil];
CIDetector* faceDetector = [CIDetector detectorOfType:CIDetectorTypeFace context:nil options:detectorOptions];
NSDictionary *imageOptions = nil;
UIImage *tmpImage;
NSNumber* orientation;
CIImage *ciImage;
NSArray *array;
NSMutableDictionary* featuresDictionary;
Boolean useImageOptions = NO;
printf("Using CIDetectorAccuracyHigh \n");
printf("useImageOptions: %d\n", useImageOptions);
//-----------------aspectRatioThumbnail
tmpImage = [[UIImage alloc] initWithCGImage:self.asset.aspectRatioThumbnail];
orientation = [NSNumber numberWithInt:tmpImage.imageOrientation];
printf("------------ aspectRatioThumbnail %f %f orientation: %d\n", tmpImage.size.width, tmpImage.size.height, [orientation integerValue]);
ciImage = [CIImage imageWithCGImage:tmpImage.CGImage];
if (ciImage == nil) printf("----------!!!aspectRatioThumbnail: ciImage is nil \n");
imageOptions = [NSDictionary dictionaryWithObjectsAndKeys:orientation, CIDetectorImageOrientation,
CIDetectorAccuracyHigh, CIDetectorAccuracy, nil];
if (useImageOptions) {
array = [faceDetector featuresInImage:ciImage];
} else {
array = [faceDetector featuresInImage:ciImage options:imageOptions];
}
featuresDictionary = [self convertFeaturesToDictionary:array];
NSLog(@"aspectRatioThumbnail: features %@", featuresDictionary);
//-----------------fullScreenImage
tmpImage = [[UIImage alloc] initWithCGImage:self.asset.defaultRepresentation.fullScreenImage];
orientation = [NSNumber numberWithInt:tmpImage.imageOrientation];
printf("------------ fullScreenImage %f %f orientation: %d\n", tmpImage.size.width, tmpImage.size.height, [orientation integerValue]);
ciImage = [CIImage imageWithCGImage:tmpImage.CGImage];
if (ciImage == nil) printf("----------!!!fullScreenImage: ciImage is nil \n");
imageOptions = [NSDictionary dictionaryWithObjectsAndKeys:orientation, CIDetectorImageOrientation,
CIDetectorAccuracyHigh, CIDetectorAccuracy, nil];
if (useImageOptions) {
array = [faceDetector featuresInImage:ciImage];
} else {
array = [faceDetector featuresInImage:ciImage options:imageOptions];
}
featuresDictionary = [self convertFeaturesToDictionary:array];
NSLog(@"fullScreenImage: features %@", featuresDictionary);
//-----------------fullResolutionImage
tmpImage = [[UIImage alloc] initWithCGImage:self.asset.defaultRepresentation.fullResolutionImage];
orientation = [NSNumber numberWithInt:tmpImage.imageOrientation];
printf("------------ fullResolutionImage %f %f orientation: %d\n", tmpImage.size.width, tmpImage.size.height, [orientation integerValue]);
ciImage = [CIImage imageWithCGImage:tmpImage.CGImage];
if (ciImage == nil) printf("----------!!!fullResolutionImage: ciImage is nil \n");
imageOptions = [NSDictionary dictionaryWithObjectsAndKeys:orientation, CIDetectorImageOrientation,
CIDetectorAccuracyHigh, CIDetectorAccuracy, nil];
if (useImageOptions) {
array = [faceDetector featuresInImage:ciImage];
} else {
array = [faceDetector featuresInImage:ciImage options:imageOptions];
}
featuresDictionary = [self convertFeaturesToDictionary:array];
NSLog(@"fullResolutionImage: features %@", featuresDictionary);
}
- (NSMutableDictionary*)convertFeaturesToDictionary:(NSArray*)foundFaces
{
NSMutableDictionary * faceFeatures = [[NSMutableDictionary alloc] init];
if (foundFaces.count) {
CIFaceFeature *face = [foundFaces objectAtIndex:0];
NSNumber* hasMouthPosition = [NSNumber numberWithBool:face.hasMouthPosition];
NSNumber* hasLeftEyePosition = [NSNumber numberWithBool:face.hasLeftEyePosition];
NSNumber* hasRightEyePosition = [NSNumber numberWithBool:face.hasRightEyePosition];
[faceFeatures setValue:hasMouthPosition forKey:@"hasMouthPosition"];
[faceFeatures setValue:hasLeftEyePosition forKey:@"hasLeftEyePosition"];
[faceFeatures setValue:hasRightEyePosition forKey:@"hasRightEyePosition"];
NSString * boundRect = NSStringFromCGRect(face.bounds);
// NSLog(@"------------boundRect %@", boundRect);
[faceFeatures setValue:boundRect forKey:@"bounds"];
if (hasMouthPosition){
NSString * mouthPosition = NSStringFromCGPoint(face.mouthPosition);
[faceFeatures setValue:mouthPosition forKey:@"mouthPosition"];
}
if (hasLeftEyePosition){
NSString * leftEyePosition = NSStringFromCGPoint(face.leftEyePosition);
[faceFeatures setValue:leftEyePosition forKey:@"leftEyePosition"];
}
if (hasRightEyePosition){
NSString * rightEyePosition = NSStringFromCGPoint(face.rightEyePosition);
[faceFeatures setValue:rightEyePosition forKey:@"rightEyePosition"];
}
}
return faceFeatures;
}