gistfile1.m

    CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef) data);
    CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceGray();
  
    CGImageRef img = CGImageCreate(width, height, bits_allocated, bits_allocated,
                                   width,// * (bits_allocated / 8),
                                   colorspace,
                                   kCGBitmapByteOrderDefault,
                                   provider, NULL, YES,
                                   kCGRenderingIntentDefault
                                   );
    
    image = [UIImage imageWithCGImage:img];