code: def to_png_bytes(self):
      pil_frame = Image.fromarray(skimage.util.img_as_ubyte(self.frame))
  
      if len(self.frame.shape) == 3:
          pil_frame = pil_frame.convert("RGB")
  
      png_frame = io.BytesIO()
  
      pil_frame.save(png_frame, format="PNG", compress_level=3)
      png_frame.seek(0)
  
      return png_frame.read()
  
imports: import skimage.color
  import skimage.measure
  import skimage.transform
  import skimage.filters
  import skimage.morphology
  import numpy
  import io
  from PIL import Image
label_desc: Use image node_id 13 for calling the GameFrame obj's underlying member method code with example usage: obj.to_png_bytes() and returns: png_frame