Confronta RGB di due immagini in IOS

Question

Nella mia app ho bisogno di confrontare l'RGB di due immagini uguali o meno. Sto usando questo codice ...

-(CGFloat)compareImage:(UIImage *)imgPre capturedImage:(UIImage *)imgCaptured 
{  

int colorDiff; 
CFDataRef pixelData = CGDataProviderCopyData(CGImageGetDataProvider(imgPre.CGImage)); 
int myWidth = (int)CGImageGetWidth(imgPre.CGImage)/2; 
int myHeight =(int)CGImageGetHeight(imgPre.CGImage)/2; 
const UInt8 *pixels = CFDataGetBytePtr(pixelData); 

int bytesPerPixel_ = 4; 
int pixelStartIndex = (myWidth + myHeight) * bytesPerPixel_; 
UInt8 alphaVal = pixels[pixelStartIndex]; 
UInt8 redVal = pixels[pixelStartIndex + 1]; 
UInt8 greenVal = pixels[pixelStartIndex + 2]; 
UInt8 blueVal = pixels[pixelStartIndex + 3]; 
UIColor *color = [UIColor colorWithRed:(redVal/255.0f) green:(greenVal/255.0f) blue:(blueVal/255.0f) alpha:(alphaVal/255.0f)]; 
NSLog(@"color of image=%@",color); 
NSLog(@"color of R=%hhu/G=%hhu/B=%hhu",redVal,greenVal,blueVal); 


CFDataRef pixelDataCaptured = CGDataProviderCopyData(CGImageGetDataProvider(imgCaptured.CGImage)); 
int myWidthCaptured = (int)CGImageGetWidth(imgCaptured.CGImage)/2; 
int myHeightCaptured =(int)CGImageGetHeight(imgCaptured.CGImage)/2; 
const UInt8 *pixelsCaptured = CFDataGetBytePtr(pixelDataCaptured); 

int pixelStartIndexCaptured = (myWidthCaptured + myHeightCaptured) * bytesPerPixel_; 
UInt8 alphaValCaptured = pixelsCaptured[pixelStartIndexCaptured]; 
UInt8 redValCaptured = pixelsCaptured[pixelStartIndexCaptured + 1]; 
UInt8 greenValCaptured = pixelsCaptured[pixelStartIndexCaptured + 2]; 
UInt8 blueValCaptured = pixelsCaptured[pixelStartIndexCaptured + 3]; 
UIColor *colorCaptured = [UIColor colorWithRed:(redValCaptured/255.0f) green:(greenValCaptured/255.0f) blue:(blueValCaptured/255.0f) alpha:(alphaValCaptured/255.0f)]; 
NSLog(@"color of captured image=%@",colorCaptured); 
NSLog(@"color of captured image R=%hhu/G=%hhu/B=%hhu",redValCaptured,greenValCaptured,blueValCaptured); 

colorDiff=sqrt((redVal-249)*(redVal-249)+(greenVal-greenValCaptured)*(greenVal-greenValCaptured)+(blueVal-blueValCaptured)*(blueVal-blueValCaptured)); 

return colorDiff; 
} 

ma questo metodo restituisce il valore stesso RGB quando mi pongo immagine per nome.

Answer 1

@interface ViewController()<UIImagePickerControllerDelegate, UINavigationControllerDelegate> 
{ 
    IBOutlet UIImageView *imgLeft; 
    IBOutlet UIImageView *imgRight; 

    IBOutlet UILabel *lblLeft; 
    IBOutlet UILabel *lblRight; 

    IBOutlet UILabel *lblResult; 


    CGFloat redLeft,GreenLeft,BlueLeft; 
    CGFloat redRight,GreenRight,BlueRight; 
} 

@end 

@implementation ViewController 

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view, typically from a nib. 

    UITapGestureRecognizer * tapRecognizerLeft = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(imageTappedLeft:)]; 
    [imgLeft addGestureRecognizer:tapRecognizerLeft]; 
    imgLeft.userInteractionEnabled = YES; 

    UITapGestureRecognizer * tapRecognizerRight = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(imageTappedRight:)]; 
    [imgRight addGestureRecognizer:tapRecognizerRight]; 
    imgRight.userInteractionEnabled = YES; 
} 

- (void)didReceiveMemoryWarning { 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 

-(IBAction)calculateDistance:(id)sender 
{ 
    CGFloat derivedRedDiff=redLeft-redRight; 
    if (derivedRedDiff<0) { 
     derivedRedDiff*=-1; 
    } 
    CGFloat derivedGreenDiff=GreenLeft-GreenRight; 
    if (derivedGreenDiff<0) { 
     derivedGreenDiff*=-1; 
    } 
    CGFloat derivedBlueDiff=BlueLeft-BlueRight; 
    if (derivedBlueDiff<0) { 
     derivedBlueDiff*=-1; 
    } 

    CGFloat distance=sqrtf(derivedRedDiff*derivedRedDiff+derivedGreenDiff*derivedGreenDiff+derivedBlueDiff*derivedBlueDiff); 
    NSLog(@"Distance = %f",distance); 
    lblResult.text=[NSString stringWithFormat:@"Distance = %f",distance]; 
} 



-(void)imageTappedLeft:(UITapGestureRecognizer *)recognizer 
{ 
    CGPoint point = [recognizer locationInView:imgLeft]; 

    UIGraphicsBeginImageContext(imgLeft.bounds.size); 
    CGContextRef context = UIGraphicsGetCurrentContext(); 
    [imgLeft.layer renderInContext:context]; 

    int bpr =(int) CGBitmapContextGetBytesPerRow(context); 
    unsigned char * data = CGBitmapContextGetData(context); 
    if (data != NULL) 
    { 
     int offset = bpr*round(point.y) + 4*round(point.x); 
     int blue = data[offset+0]; 
     int green = data[offset+1]; 
     int red = data[offset+2]; 
     int alpha = data[offset+3]; 

     CGFloat derivedAlpha=alpha/255.0f; 

     NSLog(@"%d %d %d %d %f", alpha, red, green, blue,derivedAlpha); 

     redLeft=red; 
     GreenLeft=green; 
     BlueLeft=blue; 

     lblLeft.text=[NSString stringWithFormat:@"%d %d %d %f", red, green, blue,derivedAlpha]; 
    } 

    UIGraphicsEndImageContext(); 
} 

-(void)imageTappedRight:(UITapGestureRecognizer *)recognizer 
{ 
    CGPoint point = [recognizer locationInView:imgRight]; 

    UIGraphicsBeginImageContext(imgRight.bounds.size); 
    CGContextRef context = UIGraphicsGetCurrentContext(); 
    [imgRight.layer renderInContext:context]; 

    int bpr =(int) CGBitmapContextGetBytesPerRow(context); 
    unsigned char * data = CGBitmapContextGetData(context); 
    if (data != NULL) 
    { 
     int offset = bpr*round(point.y) + 4*round(point.x); 
     int blue = data[offset+0]; 
     int green = data[offset+1]; 
     int red = data[offset+2]; 
     int alpha = data[offset+3]; 

     CGFloat derivedAlpha=alpha/255.0f; 

     NSLog(@"%d %d %d %d %f", alpha, red, green, blue,derivedAlpha); 

     redRight=red; 
     GreenRight=green; 
     BlueRight=blue; 

     lblRight.text=[NSString stringWithFormat:@"%d %d %d %f", red, green, blue,derivedAlpha]; 
    } 

    UIGraphicsEndImageContext(); 
}