Best solution YUV -> RGB

RgbConversion.kt

class RgbConversion(val rs: RenderScript, private val feedSize: Size, private val hasRotate: Boolean = true) {
    private var mInputAllocation: Allocation? = null
    private var mOutputAllocation: Allocation? = null
    private var mRotatedAllocation: Allocation? = null
    private val yuvToRgb = ScriptIntrinsicYuvToRGB.create(rs, Element.U8_4(rs))
    private val rotator = ScriptC_rotator(rs)
    var bufferCallback: ((ByteBuffer) -> Unit)? = null

    val inputSurface: Surface
        get() = mInputAllocation!!.surface

    private val onBufferAvailable = Allocation.OnBufferAvailableListener {

        it.ioReceive()

        yuvToRgb.setInput(it)
        yuvToRgb.forEach(mOutputAllocation)

        if (hasRotate) {
            rotator._inImage = mOutputAllocation
            rotator._inWidth = feedSize.width
            rotator._inHeight = feedSize.height
            rotator.forEach_rotate_270_clockwise_natural(mRotatedAllocation, mRotatedAllocation)
            bufferCallback?.invoke(mRotatedAllocation!!.byteBuffer)
        } else {
            bufferCallback?.invoke(mOutputAllocation!!.byteBuffer)
        }
    }

    init {
        createAllocations(rs)

        mInputAllocation!!.setOnBufferAvailableListener(onBufferAvailable)
    }

    private fun createAllocations(rs: RenderScript) {

        val width = feedSize.width
        val height = feedSize.height
        println("Allocation $width, $height")

        val yuvType = Type.Builder(rs, Element.U8_4(rs))
            .setX(width)
            .setY(height)
            .setYuvFormat(ImageFormat.YUV_420_888)
            .create()

        mInputAllocation = Allocation.createTyped(
            rs, yuvType,
            Allocation.USAGE_IO_INPUT or Allocation.USAGE_SCRIPT
        )


        val rgbType = Type.createXY(rs, Element.RGBA_8888(rs), width, height)

        mOutputAllocation = Allocation.createTyped(
            rs, rgbType, Allocation.USAGE_SCRIPT
        )
        val rotated = Type.createXY(rs, Element.RGBA_8888(rs), height, width)

        mRotatedAllocation = Allocation.createTyped(
            rs, rotated, Allocation.USAGE_SCRIPT
        )
    }

}

YuvToRgbActivity.kt

class YuvToRgbActivity : AppCompatActivity() {
    private val aspectRatio: Rational = Rational(16, 9)
    private lateinit var renderScript: RenderScript

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        renderScript = RenderScript.create(this)
        setContentView(R.layout.activity_yuv_to_rgb)
        if (allPermissionsGranted()) {
            startCamera()
        } else {
            ActivityCompat.requestPermissions(this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS)
        }
    }

    private fun startCamera() {
        CameraX.bindToLifecycle(this, imageAnalysisSetup(), imageCaptureSetup())
    }

    fun setupPreview(): Preview {
        val previewConfig = PreviewConfig.Builder()
            .setLensFacing(CameraX.LensFacing.FRONT)
            .build()
        return Preview(previewConfig)
    }

    fun imageCaptureSetup(): ImageCapture {
        val width = 3264
        val height = 2448
        val captureConfig = ImageCaptureConfig.Builder()
            .setLensFacing(CameraX.LensFacing.FRONT)
            .setBufferFormat(ImageFormat.YUV_420_888)
            .setTargetResolution(Size(width, height))
            .build()
        val mConversionScript = RgbConversion(RenderScript.create(this), Size(width, height))
        val imagewriter = ImageWriter.newInstance(mConversionScript.inputSurface, 1)
        mConversionScript.bufferCallback = { rgbBuffer ->
            Log.d("CAPTURED!!", rgbBuffer.capacity().toString())
            val bitmapImage = Bitmap.createBitmap(height, width, Bitmap.Config.ARGB_8888)

            caturedView.post {
                rgbBuffer.rewind()
                bitmapImage.copyPixelsFromBuffer(rgbBuffer)
                caturedView.setImageBitmap(bitmapImage)
            }
        }
        val imageCapture = ImageCapture(captureConfig)
        button.setOnClickListener {
            imageCapture.takePicture(object : ImageCapture.OnImageCapturedListener() {
                override fun onCaptureSuccess(image: ImageProxy, rotationDegrees: Int) {
                    Log.d("TTA", "${image.width} ${image.height}")
                    imagewriter.queueInputImage(image.image)
                    image.close()
                }
            })
        }
        return imageCapture
    }

    fun imageAnalysisSetup(): ImageAnalysis {
        val width = 1920
        val height = 1080
        //val imageReader = ImageReader.newInstance(width, height, ImageFormat.YUV_420_888, 1)

        val imageReadConfig = ImageAnalysisConfig.Builder().apply {
            // Use a worker thread for image analysis to prevent glitches
            setLensFacing((CameraX.LensFacing.FRONT))
            setTargetAspectRatio(aspectRatio)
            setTargetResolution(Size(width, height))
            val analyzerThread = HandlerThread("Analyser").apply { start() }
            setCallbackHandler(Handler(analyzerThread.looper))
            setImageReaderMode(ImageAnalysis.ImageReaderMode.ACQUIRE_LATEST_IMAGE)
        }
        val mConversionScript = RgbConversion(renderScript, Size(width, height))
        val imagewriter = ImageWriter.newInstance(mConversionScript.inputSurface, 1)
        val bitmapImage = Bitmap.createBitmap(height, width, Bitmap.Config.ARGB_8888)
        mConversionScript.bufferCallback = { rgbBuffer ->
            Log.d("BUFFER!!", rgbBuffer.capacity().toString())
            previewView.post {
                rgbBuffer.rewind()
                bitmapImage.copyPixelsFromBuffer(rgbBuffer)
                previewView.setImageBitmap(bitmapImage)
            }
        }
        return ImageAnalysis(imageReadConfig.build()).apply {
            analyzer = ImageAnalysis.Analyzer { image, rotationDegrees ->
                imagewriter.queueInputImage(image.image)

            }
        }
    }

    /**
     * Check if all permission specified in the manifest have been granted
     */
    private fun allPermissionsGranted(): Boolean {
        for (permission in REQUIRED_PERMISSIONS) {
            if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
                return false
            }
        }
        return true
    }

    /**
     * Process result from permission request dialog box, has the request
     * been granted? If yes, start Camera. Otherwise display a toast
     */
    override fun onRequestPermissionsResult(
        requestCode: Int, permissions: Array<String>, grantResults: IntArray
    ) {
        if (requestCode == REQUEST_CODE_PERMISSIONS) {
            if (allPermissionsGranted()) {
                caturedView.post { startCamera() }
            } else {
                Toast.makeText(
                    this,
                    "Permissions not granted by the user.",
                    Toast.LENGTH_SHORT
                ).show()
                finish()
            }
        }
    }
}