code: def test_3050():
      """
      This is known to fail if MuPDF is built without it's default third-party
      libraries, e.g. in Linux system installs.
      """
      pdf_file = fitz.open(pdf)
      for page_no, page in enumerate(pdf_file):
          zoom_x = 4.0
          zoom_y = 4.0
          matrix = fitz.Matrix(zoom_x, zoom_y)
          pix = page.get_pixmap(matrix=matrix)
          digest0 = pix.digest
          print(f"{pix.width=} {pix.height=}")
  
          def product(x, y):
              for yy in y:
                  for xx in x:
                      yield (xx, yy)
  
          n = 0
          # We use a small subset of the image because non-optimised rebase gets
          # very slow.
          for pos in product(range(100), range(100)):
              if sum(pix.pixel(pos[0], pos[1])) >= 600:
                  n += 1
                  pix.set_pixel(pos[0], pos[1], (255, 255, 255))
          digest1 = pix.digest
          print(f"{page_no=} {n=} {digest0=} {digest1=}")
          digest_expected = (
              b"\xd7x\x94_\x98\xa1<-/\xf3\xf9\x04\xec#\xaa\xee"
          )
          pix.save(
              os.path.abspath(
                  f"{__file__}/../../tests/test_3050_out.png"
              )
          )
          assert digest1 != digest0
          assert digest1 == digest_expected
  
file_path: pymudf/tests/test_pixmap.py
imports: import fitz
  import os
  import platform
  import sys
  import tempfile
  import pytest
label_desc: Use image node_id 14 for calling a global function with example usage: test_3050() without return types