UIImgeとIplImageの相互変換
Converting images between UIImage and IplImage
This content is copied from Yoshimasa's blog.
Converting images between UIImage and IplImage
OpenCV is using IplImage structure for processing, and iPhone SDK using UIImage object to display it on the screen. This means, we need a converter between UIImage and IplImage. Thankfully, we can do with iPhone SDK APIs.
Creating IplImage from UIImage is like this.
// NOTE you SHOULD cvReleaseImage() for the return value when end of the code.
- (IplImage *)CreateIplImageFromUIImage:(UIImage *)image {
// Getting CGImage from UIImage
CGImageRef imageRef = image.CGImage;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// Creating temporal IplImage for drawing
IplImage *iplimage = cvCreateImage(
cvSize(image.size.width,image.size.height), IPL_DEPTH_8U, 4
);
// Creating CGContext for temporal IplImage
CGContextRef contextRef = CGBitmapContextCreate(
iplimage->imageData, iplimage->width, iplimage->height,
iplimage->depth, iplimage->widthStep,
colorSpace, kCGImageAlphaPremultipliedLast|kCGBitmapByteOrderDefault
);
// Drawing CGImage to CGContext
CGContextDrawImage(
contextRef,
CGRectMake(0, 0, image.size.width, image.size.height),
imageRef
);
CGContextRelease(contextRef);
CGColorSpaceRelease(colorSpace);
// Creating result IplImage
IplImage *ret = cvCreateImage(cvGetSize(iplimage), IPL_DEPTH_8U, 3);
cvCvtColor(iplimage, ret, CV_RGBA2BGR);
cvReleaseImage(&iplimage);
return ret;
}
Don’t forget release IplImage after using it by cvReleaseImage!
And creating UIImage from IplImage is like this.
// NOTE You should convert color mode as RGB before passing to this function
- (UIImage *)UIImageFromIplImage:(IplImage *)image {
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// Allocating the buffer for CGImage
NSData *data =
[NSData dataWithBytes:image->imageData length:image->imageSize];
CGDataProviderRef provider =
CGDataProviderCreateWithCFData((CFDataRef)data);
// Creating CGImage from chunk of IplImage
CGImageRef imageRef = CGImageCreate(
image->width, image->height,
image->depth, image->depth * image->nChannels, image->widthStep,
colorSpace, kCGImageAlphaNone|kCGBitmapByteOrderDefault,
provider, NULL, false, kCGRenderingIntentDefault
);
// Getting UIImage from CGImage
UIImage *ret = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpace);
return ret;
}