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  • Make UIImage White Background Transparent in iOS

    @ashish.nakoti
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    If you came across to a requirement where you want to make UIImage Background Transparent then use below method to achieve it.

    +(UIImage *)changeWhiteColorTransparent: (UIImage *)image{
CGImageRef rawImageRef=image.CGImage;

const CGFloat colorMasking[6] = {222, 255, 222, 255, 222, 255};

UIGraphicsBeginImageContext(image.size);
CGImageRef maskedImageRef=CGImageCreateWithMaskingColors(rawImageRef, colorMasking);
{
    //if in iphone
    CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0.0, image.size.height);
    CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0);
}

CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, image.size.width, image.size.height), maskedImageRef);
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
CGImageRelease(maskedImageRef);
UIGraphicsEndImageContext();
return result;
}

    It will return you an image with a transparent Background. Happy Coding!!

    UIImage UIImage BackGround UIIMage Transparent background transparent ios objc
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 4 Comment(s)

  • @michelelonghi
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    about 9 years ago

    extension UIImage {

    func imageByMakingWhiteBackgroundTransparent() -> UIImage? {

    if let rawImageRef = self.CGImage {

        let colorMasking: [CGFloat] = [200, 255, 200, 255, 200, 255]

        UIGraphicsBeginImageContext(self.size)

        if let maskedImageRef = CGImageCreateWithMaskingColors(rawImageRef, colorMasking) {

            CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0.0, self.size.height)
            CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0)

            CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, self.size.width, self.size.height), maskedImageRef)

            let result = UIGraphicsGetImageFromCurrentImageContext()

            UIGraphicsEndImageContext()

            return result
        }
    }

    return nil
}

    }

  • @Mackstein
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    almost 9 years ago

    A. The code of *CGImageCreateWithMaskingColors* returns nil, probably when trying to handle an image with alpha channel. Can someone know how we can bypass this?

    And for anyone asking - Swift 2.0 code of the extension:

    extension UIImage {

    func imageByMakingWhiteBackgroundTransparent() -> UIImage? {
    if let rawImageRef = self.CGImage {
        //TODO: eliminate alpha channel if exsists
        let colorMasking: [CGFloat] = [200, 255, 200, 255, 200, 255]
        UIGraphicsBeginImageContext(self.size)
        if let maskedImageRef = CGImageCreateWithMaskingColors(rawImageRef, colorMasking) {
            CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0.0, self.size.height)
            CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0)
            CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, self.size.width, self.size.height), maskedImageRef)
            let result = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
            return result
        }
    }
    return nil
}

    }

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