Convertir l'image en problème N & B CGContext - iPhone Dev

Question

J'utilise une méthode pour convertir les images prises avec l'appareil photo en noir et blanc. Le problème que je rencontre est que si l'image est prise en mode portrait, elle tourne et s'étire dans la vue suivante. Mais, si l'on prend en paysage c'est juste trouver.

Je ne peux reproduire ce bogue que lorsque je convertis l'image en noir et blanc. Voici la méthode que j'utilise.

Je ne suis pas 100% que ce bug provient de la conversion, mais cela n'arrive que lorsqu'il est converti. Oh oui. Ceci est l'iOS 4.

/// 

- (UIImage *)convertImageToGrayScale:(UIImage *)image 
{ 

// Create image rectangle with current image width/height 
CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height); 

// Grayscale color space 
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray(); 

// Create bitmap content with current image size and grayscale colorspace 
CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, colorSpace, kCGImageAlphaNone); 

// Draw image into current context, with specified rectangle 
// using previously defined context (with grayscale colorspace) 
CGContextDrawImage(context, imageRect, [image CGImage]); 

// Create bitmap image info from pixel data in current context 
CGImageRef imageRef = CGBitmapContextCreateImage(context); 

// Create a new UIImage object 
UIImage *newImage = [UIImage imageWithCGImage:imageRef]; 

// Release colorspace, context and bitmap information 
CGColorSpaceRelease(colorSpace); 
CGContextRelease(context); 
CFRelease(imageRef); 

// Return the new grayscale image 
return newImage; 
} 

@lessfame

Answer 1

K Je l'ai.

Ce que j'ai fini par faire est de trouver cette fonction qui fait tourner les images en fonction de la transformation en fonction de l'orientation. Ce qu'il fait est corrige ce bug de rotation bizarre.

Heres l'extrait de code:

- (UIImage *)rotateImage:(UIImage *)image { 

int kMaxResolution = 320; // Or whatever 

CGImageRef imgRef = image.CGImage; 

CGFloat width = CGImageGetWidth(imgRef); 
CGFloat height = CGImageGetHeight(imgRef); 


CGAffineTransform transform = CGAffineTransformIdentity; 
CGRect bounds = CGRectMake(0, 0, width, height); 
if (width > kMaxResolution || height > kMaxResolution) { 
    CGFloat ratio = width/height; 
    if (ratio > 1) { 
     bounds.size.width = kMaxResolution; 
     bounds.size.height = bounds.size.width/ratio; 
    } 
    else { 
     bounds.size.height = kMaxResolution; 
     bounds.size.width = bounds.size.height * ratio; 
    } 
} 

CGFloat scaleRatio = bounds.size.width/width; 
CGSize imageSize = CGSizeMake(CGImageGetWidth(imgRef), CGImageGetHeight(imgRef)); 
CGFloat boundHeight; 
UIImageOrientation orient = image.imageOrientation; 
switch(orient) { 

    case UIImageOrientationUp: //EXIF = 1 
     transform = CGAffineTransformIdentity; 
     break; 

    case UIImageOrientationUpMirrored: //EXIF = 2 
     transform = CGAffineTransformMakeTranslation(imageSize.width, 0.0); 
     transform = CGAffineTransformScale(transform, -1.0, 1.0); 
     break; 

    case UIImageOrientationDown: //EXIF = 3 
     transform = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height); 
     transform = CGAffineTransformRotate(transform, M_PI); 
     break; 

    case UIImageOrientationDownMirrored: //EXIF = 4 
     transform = CGAffineTransformMakeTranslation(0.0, imageSize.height); 
     transform = CGAffineTransformScale(transform, 1.0, -1.0); 
     break; 

    case UIImageOrientationLeftMirrored: //EXIF = 5 
     boundHeight = bounds.size.height; 
     bounds.size.height = bounds.size.width; 
     bounds.size.width = boundHeight; 
     transform = CGAffineTransformMakeTranslation(imageSize.height, imageSize.width); 
     transform = CGAffineTransformScale(transform, -1.0, 1.0); 
     transform = CGAffineTransformRotate(transform, 3.0 * M_PI/2.0); 
     break; 

    case UIImageOrientationLeft: //EXIF = 6 
     boundHeight = bounds.size.height; 
     bounds.size.height = bounds.size.width; 
     bounds.size.width = boundHeight; 
     transform = CGAffineTransformMakeTranslation(0.0, imageSize.width); 
     transform = CGAffineTransformRotate(transform, 3.0 * M_PI/2.0); 
     break; 

    case UIImageOrientationRightMirrored: //EXIF = 7 
     boundHeight = bounds.size.height; 
     bounds.size.height = bounds.size.width; 
     bounds.size.width = boundHeight; 
     transform = CGAffineTransformMakeScale(-1.0, 1.0); 
     transform = CGAffineTransformRotate(transform, M_PI/2.0); 
     break; 

    case UIImageOrientationRight: //EXIF = 8 
     boundHeight = bounds.size.height; 
     bounds.size.height = bounds.size.width; 
     bounds.size.width = boundHeight; 
     transform = CGAffineTransformMakeTranslation(imageSize.height, 0.0); 
     transform = CGAffineTransformRotate(transform, M_PI/2.0); 
     break; 

    default: 
     [NSException raise:NSInternalInconsistencyException format:@"Invalid image orientation"]; 

} 

UIGraphicsBeginImageContext(bounds.size); 

CGContextRef context = UIGraphicsGetCurrentContext(); 

if (orient == UIImageOrientationRight || orient == UIImageOrientationLeft) { 
    CGContextScaleCTM(context, -scaleRatio, scaleRatio); 
    CGContextTranslateCTM(context, -height, 0); 
} 
else { 
    CGContextScaleCTM(context, scaleRatio, -scaleRatio); 
    CGContextTranslateCTM(context, 0, -height); 
} 

CGContextConcatCTM(context, transform); 

CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef); 
UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext(); 
UIGraphicsEndImageContext(); 

return imageCopy; } 

La méthode renvoie une image que je peux alors utiliser dans mon NOIR ET BLANC Fonction

- (UIImage *)convertImageToGrayScale:(UIImage *)image { 

image = [self rotateImage:image];//THIS IS WHERE REPAIR THE ROTATION PROBLEM 

// Create image rectangle with current image width/height 
CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height); 

// Grayscale color space 
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray(); 

// Create bitmap content with current image size and grayscale colorspace 
CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, colorSpace, kCGImageAlphaNone); 

// Draw image into current context, with specified rectangle 
// using previously defined context (with grayscale colorspace) 
CGContextDrawImage(context, imageRect, [image CGImage]); 

// Create bitmap image info from pixel data in current context 
CGImageRef imageRef = CGBitmapContextCreateImage(context); 

// Create a new UIImage object 
UIImage *newImage = [UIImage imageWithCGImage:imageRef]; 

// Release colorspace, context and bitmap information 
CGColorSpaceRelease(colorSpace); 
CGContextRelease(context); 
CFRelease(imageRef); 

// Return the new grayscale image 
return newImage; } 

Amusez-vous!

Answer 2

Je pense que je compris cela. Va tester maintenant.

Il s'avère qu'il existe des indicateurs d'orientation UIImage. J'ai trouvé un fil de support à: http://discussions.apple.com/message.jspa?messageID=7276709

Mon point de vue sur est d'utiliser un commutateur pour vérifier l'orientation et basé sur de qui pivotent à son orientation.

Je publie le code après l'avoir compris.

Stanks!

• @lessfame

Answer 3

Je modifié pour être en mesure de traiter 2.0 images redimensionnées sans résolution perdre:

- (UIImage *)convertImageToGrayScale:(UIImage *)image { 
    // Create image rectangle with current image width/height 
    CGRect imageRect = CGRectMake(0, 0, image.scale*image.size.width, image.scale*image.size.height); 

    // Grayscale color space 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray(); 

    // Create bitmap content with current image size and grayscale colorspace 
    CGContextRef context = CGBitmapContextCreate(nil, image.scale*image.size.width, image.scale*image.size.height, 8, 0, colorSpace, kCGImageAlphaNone); 

    // Draw image into current context, with specified rectangle 
    // using previously defined context (with grayscale colorspace) 
    CGContextDrawImage(context, imageRect, [image CGImage]); 

    // Create bitmap image info from pixel data in current context 
    CGImageRef imageRef = CGBitmapContextCreateImage(context); 

    // Create a new UIImage object 
    UIImage *newImage = [UIImage imageWithCGImage:imageRef scale:image.scale orientation:image.imageOrientation]; 

    // Release colorspace, context and bitmap information 
    CGColorSpaceRelease(colorSpace); 
    CGContextRelease(context); 
    CFRelease(imageRef); 

    // Return the new grayscale image 
    return newImage; 
}