I found some Python2 code to extract images from Excel files.
I have a very fundamental question: Where shall I specify the path of my target excel file?
Or does it only work with an active opened Excel file?
import win32com.client       # Need pywin32 from pip
from PIL import ImageGrab    # Need PIL as well
import os
excel = win32com.client.Dispatch("Excel.Application")
workbook = excel.ActiveWorkbook
wb_folder = workbook.Path
wb_name = workbook.Name
wb_path = os.path.join(wb_folder, wb_name)
#print "Extracting images from %s" % wb_path
print("Extracting images from", wb_path)
image_no = 0
for sheet in workbook.Worksheets:
    for n, shape in enumerate(sheet.Shapes):
        if shape.Name.startswith("Picture"):
            # Some debug output for console
            image_no += 1
            print("---- Image No. %07i ----", image_no)
            # Sequence number the pictures, if there's more than one
            num = "" if n == 0 else "_%03i" % n
            filename = sheet.Name + num + ".jpg"
            file_path = os.path.join (wb_folder, filename)
            #print "Saving as %s" % file_path    # Debug output
            print('Saving as ', file_path)
            shape.Copy() # Copies from Excel to Windows clipboard
            # Use PIL (python imaging library) to save from Windows clipboard
            # to a file
            image = ImageGrab.grabclipboard()
            image.save(file_path,'jpeg')