iOS開發之UIImage黑白處理

 

//通過修改圖片飽和度將圖片變為黑白（鏤空位置不影響）

- (UIImage*) convertImageToGreyScale:(UIImage*) image

{

    CIImage *beginImage = [CIImage imageWithCGImage:image.CGImage];

    CIFilter * filter = [CIFilter filterWithName:@"CIColorControls"];

    [filter setValue:beginImage forKey:kCIInputImageKey];

    //飽和度 0---2 默認為1

    [filter setValue:[NSNumber numberWithFloat:0] forKey:@"inputSaturation"];

    // 得到過濾后的圖片

    CIImage *outputImage = [filter outputImage];

    // 轉換圖片, 創建基於GPU的CIContext對象

    CIContext *context = [CIContext contextWithOptions: nil];

    CGImageRef cgimg = [context createCGImage:outputImage fromRect:[outputImage extent]];

    UIImage *newImg = [UIImage imageWithCGImage:cgimg];

    // 釋放C對象

    CGImageRelease(cgimg);

    return newImg;

}

 

//將圖片變為黑邊反轉（鏤空部位為黑色）

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

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

　　CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();

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

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

　　CGImageRef imageRef = CGBitmapContextCreateImage(context);

　　UIImage *newImage = [UIImage imageWithCGImage:imageRef];

　　CGColorSpaceRelease(colorSpace); CGContextRelease(context);

　　CFRelease(imageRef);

　　return newImage;

}