Get size of a UIImage (bytes length) not height and width

Question

I\'m trying to get the length of a UIImage. Not the width or height of the image, but the size of the data.

Answer 1

I'm not sure your situation. If you need the actual byte size, I don't think you do that. You can use UIImagePNGRepresentation or UIImageJPEGRepresentation to get an NSData object of compressed data of the image.

I think you want to get the actual size of uncompressed image(pixels data). You need to convert UIImage* or CGImageRef to raw data. This is an example of converting UIImage to IplImage(from OpenCV). You just need to allocate enough memory and pass the pointer to CGBitmapContextCreate's first arg.

UIImage *image = //Your 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);

IplImage *ret = cvCreateImage(cvGetSize(iplimage), IPL_DEPTH_8U, 3);
cvCvtColor(iplimage, ret, CV_RGBA2BGR);
cvReleaseImage(&iplimage);