How to take 16 bit/channel grayscale screenshots?

Hello all,

I need to take 16 (or 32) bit/channel screenshots from my grayscale view and load them to Python. I use the following code but it seems to be giving 8 bit/channel RGB images. Please let me know what I am doing wrong. Thank you,

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class ScreenshotHandler: MonoBehaviour
 {
 
     private static ScreenshotHandler instance;
 
     private Camera myCamera;
     private bool takeScreenshotOnNextFrame;
 
     private void Awake()
     {
         instance = this;
         myCamera = gameObject.GetComponent<Camera>();
     }
 
     private void OnPostRender()
     {
         if (takeScreenshotOnNextFrame)
         {
             takeScreenshotOnNextFrame = false;
             RenderTexture renderTexture = myCamera.targetTexture;
 
             Texture2D renderResult = new Texture2D(renderTexture.width, renderTexture.height, TextureFormat.R16, false);
             Rect rect = new Rect(0, 0, renderTexture.width, renderTexture.height);
             renderResult.ReadPixels(rect, 0, 0);
 
             byte[] byteArray = renderResult.EncodeToPNG();
             System.IO.File.WriteAllBytes(Application.dataPath + "/CameraScreenshot.png", byteArray);
             Debug.Log("Saved CameraScreenshot.png");
 
             RenderTexture.ReleaseTemporary(renderTexture);
             myCamera.targetTexture = null;
         }
     }
 
     private void TakeScreenshot(int width, int height)
     {
         myCamera.targetTexture = RenderTexture.GetTemporary(width, height, 16);
         takeScreenshotOnNextFrame = true;
     }
 
     public static void TakeScreenshot_Static(int width, int height)
     {
         instance.TakeScreenshot(width, height);
     }
 }