rotate a UIImage help

ddavtian · 05-26-2008, 10:55 PM

Hi,

Any image taken with the camera and saved as a UIImage doesn't seem to come out right, orientation wise that is. Does anyway have a solution on how to rotate the image to it's proper state?

Many Thanks
Dave

Fastrak · 05-27-2008, 01:24 AM

Either add it to a UIImageView and set a rotation transform or, if you need it to stay a UIImage, you will need to drop down to core graphics to rotate it (or flip it)

ddavtian · 05-27-2008, 11:42 PM

I think working with a UIImageView would be easier, do you my any chance have an example you can share?

Basically what I want to do is this

UIIMage --> UIImageView --> rotate --> UIImage --> send

Currently I have the UIImage and it's sending as is.

Thanks in Advance
Dave

scottiphone · 05-28-2008, 02:32 AM

Look up UIImageOrientation in the docs. There are settings that can be applied to UIImage.
I think there's info in the editinfo from the camera picker.

If you want to rotate it directly use CGAffineTransformRotate.

ddavtian · 05-28-2008, 09:47 PM

Hmm would this work?

+(UIImage *)rotateImage

UIImage *)image {

int orient = image.imageOrientation;

UIImageView *imageView = [[UIImageView alloc] init];

UIImage *imageCopy = [[UIImage alloc] initWithCGImage:image.CGImage];

switch (orient) {
case UIImageOrientationLeft:
imageView.transform = CGAffineTransformMakeRotation(3.0 * M_PI / 2.0);
break;
case UIImageOrientationRight:
imageView.transform = CGAffineTransformMakeRotation(M_PI / 2.0);
break;
case UIImageOrientationDown: //EXIF = 3
imageView.transform = CGAffineTransformMakeRotation(M_PI);
default:
break;
}

imageView.image = imageCopy;
return (imageView.image);
}

scottiphone · 05-29-2008, 05:13 PM

I haven't studied your code in too much detail but place a draw function after the transform to see if it's working.

Note that if you use orientation I don't think you have to rotate it manually. Since drawing ir a different orientation for the UI compared to some other image libraries they try to make it reasonable to do. Do a search of the example code for orientation or transform.
Once again try drawing before and after so you can see what happens.

You may have to draw and capture it.

Note that you'll have leaks since you've allocated a couple of objects but haven't released them.

pinpoint · 02-02-2009, 01:19 PM

did anyone get this to work?

I'm examining the UIImage.orientation of both pics selected from the library and pics taken with the camera, and they're both "UP"... yet my camera pics show on the screen sideways. Oddly enough i'm using the same technique to generate thumbnails, and they're coming out the right orientation.

Thanks!

pinpoint · 02-02-2009, 01:27 PM

OK, I was looking at the image at the wrong point- the UIImage returned by the camera is "RIGHT", not UP.

Once i've saved the image out, and re-read it back in again it's UP.

That still leaves me with the task of rotating the image 90 degrees before I save it... anyone have a little code that works?

Thanks!

pinpoint · 02-03-2009, 05:50 PM

Quote:

Originally Posted by pinpoint

OK, I was looking at the image at the wrong point- the UIImage returned by the camera is "RIGHT", not UP.

Once i've saved the image out, and re-read it back in again it's UP.

That still leaves me with the task of rotating the image 90 degrees before I save it... anyone have a little code that works?

Thanks!

Found code that does this here. Works like a charm.

svveet · 10-07-2009, 10:40 PM

Hi,

Ive used his code but my images are still the same.

Im not sure how his code works, can someone guide me how to rotate back the image with his code?

Logic High Software UIImage fix

Here is my code:

Code:

UIImage *imageimage2 = [[UIImage alloc] initWithContentsOfFile:pathToImage];
[self scaleAndRotateImage:imageimage2];

this is his code, i have modified a bit at the end

Code:

- (void)scaleAndRotateImage:(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();
	
	[self setRotatedImage:imageCopy];
	//return imageCopy;
}

svveet · 10-07-2009, 11:09 PM

fixed, i need to rotate it before i save the camera image to file

Quote:

Originally Posted by svveet

Hi,

Ive used his code but my images are still the same.

Im not sure how his code works, can someone guide me how to rotate back the image with his code?

Logic High Software UIImage fix

Here is my code:

Code:

UIImage *imageimage2 = [[UIImage alloc] initWithContentsOfFile:pathToImage];
[self scaleAndRotateImage:imageimage2];

this is his code, i have modified a bit at the end

Code:

- (void)scaleAndRotateImage:(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();
	
	[self setRotatedImage:imageCopy];
	//return imageCopy;
}