imageBlur.kt

    private fun alphaBlend(imageSrc:Mat, blurredImage: Mat, blurredMask: Mat): Mat{

        val total = imageSrc.width() * imageSrc.height()
        val channels = imageSrc.channels()
        val size = total * channels

        val array = FloatArray(size)
        val array1 = FloatArray(size)
        val array2 = FloatArray(size)

        val array3 = FloatArray(size)
        imageSrc.convertTo(imageSrc, CV_32F)
        blurredImage.convertTo(blurredImage, CV_32F)
        blurredMask.convertTo(blurredMask, CV_32F)

        val destination = Mat(imageSrc.size(), imageSrc.type())

        imageSrc.get(0,0, array)
        blurredImage.get(0,0, array1)
        blurredMask.get(0,0, array2)

        for (index in 0 until size){
            val pixel = array[index]
            val blurredPixel = array1[index]
            val blurVal = (array2[index]) / 255.0f

            val newValue = ((blurVal * blurredPixel) + ((1.0f - blurVal) * pixel))
            array3[index] = newValue
        }
        destination.put(0,0, array3)
        destination.convertTo(destination, CV_8UC3)
        return destination
    }

    private suspend fun blurImage(bitmap: Bitmap):Bitmap {
        return withContext(Dispatchers.IO) {
            val imageSrc = Mat()

            Utils.bitmapToMat(bitmap, imageSrc)

            val innerMask = Mat.zeros(imageSrc.size(), imageSrc.type())

            //thickness set to -1 for inner fill
            Imgproc.circle(
                innerMask,
                Point(imageSrc.width() / 2.0, imageSrc.height() / 1.5),
                600,
                Scalar.all(255.0),
                -1
            )

            val blurredImage = Mat(imageSrc.size(), imageSrc.type())
            Imgproc.blur(imageSrc, blurredImage, Size(64.0, 64.0))

            val blurredMask = Mat(innerMask.size(), innerMask.type())
            Imgproc.blur(innerMask, blurredMask, Size(64.0, 64.0))

            val merge = alphaBlend(imageSrc, blurredImage, blurredMask)

            val copy = Bitmap.createBitmap(merge.width(), merge.height(), Bitmap.Config.ARGB_8888)
            Utils.matToBitmap(merge, copy)
            copy
        }
    }