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- (UIImage *)convertImageToGrayScale:(UIImage *)image { 

// Create image rectangle with current image width/height 

CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height);

// Grayscale color space 

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();

// Create bitmap content with current image size and grayscale colorspace 

CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, colorSpace, kCGImageAlphaNone);

// Draw image into current context, with specified rectangle 

// using previously defined context (with grayscale colorspace) 

CGContextDrawImage(context, imageRect, [image CGImage]);

// Create bitmap image info from pixel data in current context 

CGImageRef imageRef = CGBitmapContextCreateImage(context);

// Create a new UIImage object  

UIImage *newImage = [UIImage imageWithCGImage:imageRef];

// Release colorspace, context and bitmap information 

CGColorSpaceRelease(colorSpace);

CGContextRelease(context);

CFRelease(imageRef);

// Return the new grayscale image 

return newImage;

}