How to extract mask images (color mapping) from UE5 as png(ARK Devkit)

Hi, I’m new in UE5, and trying to find out how to extract these 2 images from ARK Devkit.

So far I know about the High Resolution Screenshot + dept pass + Buff Visualize - Base color and Scene Capture 2D + Render Target but both don’t give the result as good the these 2 images. High Res Capture still leave green border around the dino(left pic), meanwhile the Scene Capture 2d doesn’t give clean mask image(right pic). I wonder if anyone know how to get that clean mask image(right pic). The picture below is from the guy on discord, it looks very clean.

Thank you for reading and I hope someone will help me with this.