Inverting back resized and Grayscaled TensorBuffer

Question

I have a bg removal model that takes in 512x512 RGB image and outputs a 512x512 Grayscale. How can i resize it back to original Widths and Heights, and invert this creepy Grayscale back to RGB?

 // Using here LiteRt support library for preprocessing
 val inputImageProcessor = ImageProcessor.Builder()
 .add(ResizeOp(512, 512, ResizeOp.ResizeMethod.NEAREST_NEIGHBOR))
 .build()
 val inputTensorImage = TensorImage(DataType.FLOAT32)
 inputTensorImage.load(bitmap)
 val processedInputImage = inputImageProcessor.process(inputTensorImage)
 val inputImageByteBuffer = processedInputImage.buffer
 // Creating Inputs for inference
 val image = TensorBuffer.createFixedSize(intArrayOf(1, 512, 512, 3), DataType.FLOAT32)
 image.loadBuffer(inputImageByteBuffer)
 val outputs = model.process(image)
 val masks = outputs.masksAsTensorBuffer
 // Trying to postprocess back and inverting, but with no results :(
 val outputImageProcessor = ImageProcessor.Builder()
 .add(ResizeOp(bitmap.height, bitmap.width, ResizeOp.ResizeMethod.BILINEAR))
 .build()
 val outputTensorImage = TensorImage(DataType.FLOAT32)
 outputTensorImage.load(segmentationMasks)
 val processedOutputImage = outputImageProcessor.process(outputTensorImage)
 val outputBitmap = processedOutputImage.bitmap