Iphone Convert IplImage to UIImage and vice versa causes rotation

Question

I use code to convert between iplimage and uiimage. I take a picture taken from the camera (UIImage) and convert it to iplimage and vice versa using the code below. Unfortunately, this causes the image to rotate and stretch 90 degrees. so if I take a 320x480 image, it will return a 320x480 image, but the image will be rotated and resized to look like it rotated 90 degrees (i.e., the image is 480x320), then it will not scale evenly ... I can't figure it out out - everything seems to be correct (byte order, etc.)

+(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

I had the same problem and I still didn't find out how to change the two methods so that they would not rotate the image.

Instead, I turned UIImage, for example. my code is as follows:

 //Change the rotation here UIImage *imageCam= [UIImage imageWithCGImage:newImage scale:1.0 orientation:UIImageOrientationUp]; //Convert UIImage IplImage *image = [self CreateIplImageFromUIImage:imageCam]; 

Answer 2

Just change

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

in

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

Answer 3

I had the same problem and found a solution - change CreateIplImageFromUIImage as follows:

 - (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; }