iPhone: How to change camera photo quality - iphone

Question

I've not found a answer to this question anywhere, but this seems like a typical problem:
I am taking pictures from an iPhone 4, and I have to send these pics to a server through a POST-Request, but the server does not accept pictures that are bigger than 0,5 MB, so I have to compress the pictures before I send them. In order to achieve this, I am calling following method: "NSData *imageData = UIImageJPEGRepresentation(tempImage, 0.7);", which means: I am compriming the image data, and it takes a lot of time (about 10s / pic).
Is there any way to control the quality of the camera device in order to take low quality pictures?
Thanks in advance for helping.

Answer 1

Anything that will block the main thread should be done in a background thread, including converting an image to a JPEG. So you should start the JPEG conversion using performSelectorInBackground:withObject: and, when the conversion is done, pass the resulting NSData object back to the main thread.
- (void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info {
UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
[self dismissModalViewControllerAnimated:YES];
[self performSelectorInBackground:#selector(encodePhotoInBackground:) withObject:image];
}
- (void)encodePhotoInBackground:(UIImage*)image {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSData *imageData = UIImageJPEGRepresentation(image, 0.60);
[self performSelectorOnMainThread:#selector(saveImageData:) withObject:imageData waitUntilDone:NO];
[pool release];
}
- (void)saveImageData:(NSData*)imageData {
// Do something with the image
}