[iPhone SDK] How to get raw pixel from UIImage

You can extract raw pixel info from UIImage with Quartz 2D APIs.
By follwing code, you can access CGImage pointer from UIImage.

UIImage* source = [UIImage imageNamed:@"image.png"];
CGImageRef inputImage = [source CGImage];

And, CGImageGetDataProvider and CFDataGetBytePtr enable to access raw pixel value (such as RGBA), bytes per pixel and bytes per row of the raw bitmap image.

CFDataRef inputData = CGDataProviderCopyData(CGImageGetDataProvider(inputImageRef));
unsigned char *pixelData = (unsigned char *) CFDataGetBytePtr(inputData);
int length = CFDataGetLength(inputData);
size_t width = CGImageGetWidth(inputImageRef);
size_t height = CGImageGetHeight(inputImageRef);
size_t bitsPerComponent = CGImageGetBitsPerComponent(inputImageRef);
size_t bitsPerPixel = CGImageGetBitsPerPixel(inputImageRef);
size_t bytesPerRow = CGImageGetBytesPerRow(inputImageRef);
CGColorSpaceRef colorspace = CGImageGetColorSpace(inputImageRef);
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(inputImageRef);
for (int index = 0; index < length; index += 4 ) {
unsigned char red   = *(pixelData + index);
unsigned char green = *(pixelData + index + 1);
unsigned char blue  = *(pixelData + index + 2);
unsigned char alpha = *(pixelData + index + 3);
}

Color component alignment may be RGBA?