How to Change contrast in Camera1 api PreviewCallback -Android

Question

I am developing an Android app using Camera1 API. I want to dynamically adjust the contrast of the preview image captured by the camera. How should I do this? I learned about the PreviewCallback callback method. Should I make adjustments in this callback instead?

override fun onPreviewFrame(data: ByteArray?, camera: Camera?) {
    if (data == null || camera == null) return

    // Get the format and size of the camera preview data
    val parameters = camera.parameters
    val previewSize = parameters.previewSize

    // Convert the preview data to YuvImage
    val yuvMat = Mat(previewSize.height + previewSize.height / 2, previewSize.width, CvType.CV_8UC1)
    yuvMat.put(0, 0, data)

    // Convert YuvImage to RGBA Mat
    val rgbaMat = Mat(previewSize, CvType.CV_8UC4)
    Imgproc.cvtColor(yuvMat, rgbaMat, Imgproc.COLOR_YUV2RGBA_NV21, 4)

    // Convert RGBA Mat to grayscale
    val grayscaleMat = Mat()
    Imgproc.cvtColor(rgbaMat, grayscaleMat, Imgproc.COLOR_RGBA2GRAY)

    // Adjust contrast
    val alpha = 1.5 // Adjust the contrast multiplier as needed
    val beta = 0.0
    grayscaleMat.convertTo(grayscaleMat, CvType.CV_8UC1, alpha, beta)

    // Convert grayscale back to RGBA
    Imgproc.cvtColor(grayscaleMat, rgbaMat, Imgproc.COLOR_GRAY2RGBA)

    // Display the result on the SurfaceView or perform other operations
    // ...

    // Release resources
    yuvMat.release()
    grayscaleMat.release()
    rgbaMat.release()

    // Manually add the buffer to ensure the camera continues to use it
    camera.addCallbackBuffer(data)
}