我正在试用新的CIFilter，CIStarShineGenerator.但是输出的图片是空白的，如何判断是否正常生成？CIColor*blue=[CIColorcolorWithString:@"0.10.50.81.0"];CIFilter*filter=[CIFilterfilterWithName:@"CIStarShineGenerator"keysAndValues:@"inputColor",blue,nil];CIImage*outputImage=[filteroutputImage];UIImage*image=[UIImageimageWithCIImage:ou