face detection iOS from camera

Question

I receive an image view

-(void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    NSString *mediaType = info[UIImagePickerControllerMediaType];

    [self dismissViewControllerAnimated:YES completion:nil];

    if ([mediaType isEqualToString:(NSString *)kUTTypeImage]) {
        UIImage *image = info[UIImagePickerControllerOriginalImage];

        //imgvprofileImage.image = image;
        //[self detectForFacesInUIImage:[UIImage imageNamed:@"image00.jpg"]];

        [self detectForFacesInUIImage:image];
    }
    else if ([mediaType isEqualToString:(NSString *)kUTTypeMovie])
    {
        // Code here to support video if enabled
    }
}

When I send a photo like this

[self detectForFacesInUIImage:[UIImage imageNamed:@"image00.jpg"]]; 

The detection works well and finds a face but when I use the image returned from the camera it doesn't work.

 [self detectForFacesInUIImage:image]

This is the function i use to detect the face

-(void)detectForFacesInUIImage:(UIImage *)facePicture
{
    CIImage* image = [CIImage imageWithCGImage:facePicture.CGImage];

    CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeFace context:nil options:[NSDictionary dictionaryWithObject:CIDetectorAccuracyLow forKey:CIDetectorAccuracy]];

    NSArray* features = [detector featuresInImage:image];

    if (features.count == 0) {
        NSLog(@"There is no faces in captured image ") ;
    }

    for(CIFaceFeature* faceObject in features)
    {
        CGRect modifiedFaceBounds = faceObject.bounds;
        modifiedFaceBounds.origin.y = facePicture.size.height-faceObject.bounds.size.height-faceObject.bounds.origin.y;

        [self addSubViewWithFrame:facePicture toRect:modifiedFaceBounds] ;
    }
}

Marucci

Answer 1

Problem is in image orientation.

Can't remember where I took this, but it works:

- (void) detectForFaces:(CGImageRef)facePicture orientation:(UIImageOrientation)orientation {


    CIImage* image = [CIImage imageWithCGImage:facePicture];

    CIContext *context = [CIContext contextWithOptions:nil];                    // 1
    NSDictionary *opts = @{ CIDetectorAccuracy : CIDetectorAccuracyLow };      // 2
    CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeFace
                                              context:context
                                              options:opts];                    // 3

    int exifOrientation;
    switch (orientation) {
        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;
    }


    opts = @{ CIDetectorImageOrientation :[NSNumber numberWithInt:exifOrientation
                                           ] };

    NSArray *features = [detector featuresInImage:image options:opts];

    if ([features count] > 0) {
        CIFaceFeature *face = [features lastObject];
        NSLog(@"%@", NSStringFromCGRect(face.bounds));
    }
}

How to use:

UIImage *image = // some image here;
[self detectForFaces:image.CGImage orientation:image.imageOrientation];

Bernal

how i get parameter UIImageOrientation ? – Marucci

@Marucci UIImage has property imageOrientation – Bernal

UIImage *image = info[UIImagePickerControllerOriginalImage]; [self detectForFaces:image.CGImage orientation:[image get]] this how i call is this right ?? and i didn't find the property ?? – Marucci

and the detection not accurate like before ?? – Marucci

when i corp the image before it was exactly the face , but now it isn't accurate at all ?? – Marucci

you can try change Accuracy in options, but should work the same. – Bernal

not the same the the previous choice get all the face , but now get from nose to neck – Marucci

accuracy depends on quality of image and size! the orientation should not affect on it. If you want you can easily rotate image with context and try it with correct image orientation, to be sure if it's not this method. – Bernal

the same problem ,,, it works fine with image i get from the internet , but with camera it returns the image and found face , but in incorrect position ? – Marucci

@Marucci Are you sure that your displayed image not deformed in imageview? With default options, content can be scaled to fit. If you actually checking like that... Check it just in case. – Bernal

no i set image to button like this [buttonProfilePic setImage:cropped forState:UIControlStateNormal]; – Marucci

first i crop the image – Marucci

@Marucci ok, no idea what's happening around this method, so I can't help. Just keep trying to find the issue. – Bernal

Answer 2

small Correction here

- (void) detectForFaces:(UIImage *)facePicture orientation:(UIImageOrientation)orientation {


CIImage* image = [CIImage imageWithCGImage:facePicture.CGImage];

CIContext *context = [CIContext contextWithOptions:nil];                    // 1
NSDictionary *opts = @{ CIDetectorAccuracy : CIDetectorAccuracyLow };      // 2
CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeFace
                                          context:context
                                          options:opts];                    // 3

int exifOrientation;
switch (orientation) {
    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;
}


opts = @{ CIDetectorImageOrientation :[NSNumber numberWithInt:exifOrientation
                                       ] };

NSArray *features = [detector featuresInImage:image options:opts];

if ([features count] > 0) {
    CIFaceFeature *face = [features lastObject];
    NSLog(@"%@", NSStringFromCGRect(face.bounds));
}}

UIImage *image = // some image here; [self detectForFaces:image orientation:image.imageOrientation];

send only image not image.CGImage This worked for me

Vanna