Iphone 将 IplImage 转换为 UIImage 并返回会导致旋转

Question

我正在使用一些代码在 iplimage 和 uiimage 之间进行转换。我拍摄了一张从相机拍摄的照片（UIImage），并将其转换为 iplimage，然后使用下面发布的代码将其转换回来。不幸的是，这会导致图像旋转并拉伸 90 度。 因此，如果我拍摄 320x480 图像，它会返回 320x480 图像，但图像已被旋转和重新缩放，因此看起来好像旋转了 90 度（即 480x320 图像），然后不均匀缩放......我无法理解out——一切似乎都是正确的（字节顺序等）

+(IplImage *)CreateIplImageFromUIImage:(UIImage *)image {
CGImageRef imageRef = image.CGImage;

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
IplImage *iplimage = cvCreateImage(cvSize(image.size.width, image.size.height), IPL_DEPTH_8U, 4);
CGContextRef contextRef = CGBitmapContextCreate(iplimage->imageData, iplimage->width, iplimage->height,
                                                iplimage->depth, iplimage->widthStep,
                                                colorSpace, kCGImageAlphaPremultipliedLast|kCGBitmapByteOrderDefault);
CGContextDrawImage(contextRef, CGRectMake(0, 0, image.size.width, image.size.height), imageRef);
CGContextRelease(contextRef);
CGColorSpaceRelease(colorSpace);

return iplimage;
}

+(UIImage *)UIImageFromIplImage:(IplImage *)image {
NSLog(@"IplImage (%d, %d) %d bits by %d channels, %d bytes/row %s", image->width, image->height, image->depth, image->nChannels, image->widthStep, image->channelSeq);

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
NSData *data = [NSData dataWithBytes:image->imageData length:image->imageSize];
CGDataProviderRef provider = CGDataProviderCreateWithCFData((CFDataRef)data);
CGImageRef imageRef = CGImageCreate(image->width, image->height,
                                    image->depth, image->depth * image->nChannels, image->widthStep,
                                    colorSpace, kCGImageAlphaPremultipliedLast|kCGBitmapByteOrderDefault,
                                    provider, NULL, false, kCGRenderingIntentDefault);
UIImage *ret = [UIImage imageWithCGImage:imageRef scale:1.0 orientation:UIImageOrientationRight];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpace);
return ret;
}

Answer 1

我也遇到了同样的问题，但我仍然不知道如何更改这两种方法以使它们不旋转图片。

相反，我旋转了 UIImage，例如我的代码如下所示：

//Change the rotation here

UIImage *imageCam= [UIImage imageWithCGImage:newImage scale:1.0 orientation:UIImageOrientationUp];

//Convert UIImage
IplImage *image = [self CreateIplImageFromUIImage:imageCam];

Answer 2

只需更改

UIImage *ret = [UIImage imageWithCGImage:imageRef scale:1.0 orientation:UIImageOrientationRight];

为：

UIImage *ret = [UIImage imageWithCGImage:imageRef scale:1.0 orientation:UIImageOrientationUp];

Answer 3

我遇到了同样的问题，我找到了解决方案 - 更改 CreateIplImageFromUIImage 像这样：

- (IplImage *)CreateIplImageFromUIImage:(UIImage *)image {

    CGImageRef imageRef = [self rotateImage:image].CGImage;
        ...........
}

- (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;
}