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swiftxcodeimage-processingcifilterporter-duff

How to multiply a color to an image in Swift?

I'm back with other doubt about moving my app from Android to iOS (which it's more difficult that I could think...).

Ok, so in this case I'm trying to colorized the next image:

enter image description here

In Android I used the next code:

public static Bitmap doNalaFilter (Bitmap src) {
     Bitmap bmBrown0 = Bitmap.createBitmap(src.getWidth(), src.getHeight(), src.getConfig());
     Canvas cBrown0 = new Canvas(bmBrown0);
     Paint paintBrown0 = new Paint();
     paintBrown0.setColorFilter(new LightingColorFilter(Color.WHITE, 0x800000));
     cBrown0.drawBitmap(bmTemp, 0, 0, paintBrown0);
     Bitmap bmBrown = Bitmap.createBitmap(src.getWidth(), src.getHeight(), src.getConfig());
     Canvas cBrown = new Canvas(bmBrown);
     cBrown.drawBitmap(src, 0, 0, null);
     Paint paintBrown = new Paint();
     paintBrown.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.MULTIPLY));
     cBrown.drawBitmap(bmBrown0, 0, 0, paintBrown);
     return bmBrown;
}

Getting the next image:

enter image description here

But in Swift I'm trying the next code:

func nalaFilter() -> UIImage? {
        let inImage = CIImage (image: self)
        let SRGBImage = inImage?.applyingFilter("CILinearToSRGBToneCurve")

        dynamic let brownMatrix = CIFilter (name: "CIMultiplyBlendMode")

        let brownRect = CGRect (
            x: (SRGBImage?.extent.origin.x)!,
            y: (SRGBImage?.extent.origin.y)!,
            width: (SRGBImage?.extent.size.width)!,
            height: (SRGBImage?.extent.size.height)!)
        let brownColor = CIColor (red: 128.0/255.0, green: 0.0, blue: 0.0)
        let brownOverlay = CIImage (color: brownColor)
        let brownCroppedImage = brownOverlay.cropped(to: brownRect)
        brownMatrix?.setValue(SRGBImage, forKey: kCIInputImageKey)
        brownMatrix?.setValue(brownCroppedImage, forKey: kCIInputBackgroundImageKey)
        let brownOutImage = brownMatrix?.outputImage

        let linearImage = brownOutImage?.applyingFilter("CISRGBToneCurveToLinear")

        let cgImage = CIContext().createCGImage(linearImage!, from: linearImage!.extent)
        return UIImage (cgImage: cgImage!)
}

And I'm getting this!

enter image description here

Does anybody have an idea about one Swift code which can work on the same way that in Android?

Thanks in advance!

Solution

  • Finally I got the next code which solves my problem:

    func nalaFilter() -> UIImage? {
        let brownColor = CIColor (red: 128.0/255.0, green: 0.0, blue: 0.0)
        let brownRect = CGRect (origin: .zero, size: self.size)

        //Colored image
        UIGraphicsBeginImageContextWithOptions(brownRect.size, true, 0.0)
        brownColor.setFill()
        UIRectFill(brownRect)
        let brownColoredImage = UIGraphicsGetImageFromCurrentImageContext()
        let brownContext = UIGraphicsGetCurrentContext()
        brownContext!.setFillColor(UIColor.white.cgColor)
        brownContext!.fill(brownRect)
        self.draw(in: brownRect, blendMode: .normal, alpha: 1)
        brownColoredImage?.draw(in: brownRect, blendMode: .colorDodge, alpha: 1)
        let outBrown0Image = UIGraphicsGetImageFromCurrentImageContext()

        //Multiplied image
        self.draw(in: brownRect, blendMode: .normal, alpha: 1)
        outBrown0Image?.draw(in: brownRect, blendMode: .multiply, alpha: 1)
        let outBrownImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return outBrownImage
}

    This gets exactly the same result than my Android one.