删除核心图形过滤器

我想尝试的一个有效的方法来去除这里的核心图形图像过滤器是过滤器的代码，它适用于一个UIImage删除核心图形过滤器

-(UIImage*)applyFilter { 

    CGImageRef inImage = self.CGImage; 
    CFDataRef m_dataRef = CGDataProviderCopyData(CGImageGetDataProvider(inImage)); 
    UInt8* m_pixelBuf = (UInt8*)CFDataGetBytePtr(m_dataRef); 

    int length = CFDataGetLength(m_dataRef); 

    for (int i=0; i<length; i+=4) { 
     filterSepia(m_pixelBuf, i); 
    } 

    CGContextRef ctx = CGBitmapContextCreate(m_pixelBuf, 
             CGImageGetWidth(inImage), 
             CGImageGetHeight(inImage), 
             CGImageGetBitsPerComponent(inImage), 
             CGImageGetBytesPerRow(inImage), 
             CGImageGetColorSpace(inImage), 
             CGImageGetBitmapInfo(inImage)); 

    CGImageRef imageRef = CGBitmapContextCreateImage(ctx); 
    CGContextRelease(ctx); 
    UIImage* finalImage = [UIImage imageWithCGImage:imageRef]; 
    CGImageRelease(imageRef); 
    CFRelease(m_dataRef); 
    return finalImage; 
} 

void filterSepia(UInt8 *pixelBuf, UInt32 offset) { 

    int r = offset; 
int g = offset+1; 
int b = offset+2; 

int red = pixelBuf[r]; 
int green = pixelBuf[g]; 
int blue = pixelBuf[b]; 

    pixelBuf[r] = SAFECOLOR((red*0.393)+(green*0.769)+(blue*0.189)); 
    pixelBuf[g] = SAFECOLOR((red*0.349)+(green*0.686)+(blue*0.168)); 
    pixelBuf[b] = SAFECOLOR((red*0.272)+(green*0.534)+(blue*131)); 
}

一个棕褐色效果现在我想要什么消除这种效果或类似的东西有效，当切换按钮被按下

在标题中，我可以做这样的事情：

#define SAFECOLOR(color) MIN(255, MAX(0,color)) 
BOOL toggleOn; 
@property (nonatomic, retain)UIImage* image;

在实施：

-(IBAction)sepiaButton:(id)sender { 

    UIImage* original = image; 
    if (toggleOn) { 
     [image applyFilter]; 
    } else { 
     image = original; 
    } 
    toggleOn =! toggleOn 
}

但是，由于应用了多个图像过滤器，这可能会变得效率低下，还是有更好的方法来做到这一点？

来源

2012-11-10 Sage Washabaugh