too many files open

[DPaul]

Hi,
I was given a large number of prayer cards, already scanned, ready for OCR, as usual.
Only this time the formats are different, imagine single cards, double (folded) cards and folded cards (recto & verso).
You cannot OCR them like that, you need to crop them (= cut them up) into 2 or 4 pieces, save those crops, and OCR those.
Works well,on a limited number, but with large numbers, i get:

Output:
Traceback (most recent call last):
  File "C:\VVF\BP\BP-OCR-V5.py", line 236, in <module>
    do_crop()
  File "C:\VVF\BP\BP-OCR-V5.py", line 227, in do_crop
    crop.save(dst)
  File "C:\Users\Paul\AppData\Local\Programs\Python\Python310\lib\site-packages\PIL\Image.py", line 2300, in save
    save_handler(self, fp, filename)
  File "C:\Users\Paul\AppData\Local\Programs\Python\Python310\lib\site-packages\PIL\TiffImagePlugin.py", line 1731, in _save
    _fp = os.dup(fp.fileno())
OSError: [Errno 24] Too many open files

I've tried things unsuccessfully, the basic question is: I have an image, I crop it (in memory) into x parts, I save these parts to disk.
Done, next image. Somehow it keeps file pointers open.
This is what the function looks like:

for BP in glob.glob(mappath + '\*.*'):        
            img = Image.open(BP)
            w, h = img.size
            if w < 750:
                crops = crop_image(img)
                    for idx,crop in enumerate(crops):
                        
                        dst = os.path.join(os.curdir,'data','scans-cropped',fil)  # remark: filename is modified to make them all different
                        crop.save(dst)
                        crop.close()

How can I save a few 100.000 like this ?
thx,
Paul