lllyasviel/ControlNet · error · Exception

Malformed PFM header.

Error message

Malformed PFM header.

What it means

After the PFM magic header, read_pfm expects the second line to be '<width> <height> ' matching regex ^(\d+)\s(\d+)\s$. If the dimension line is malformed the file cannot be parsed and this exception is raised.

Source

Thrown at annotator/midas/utils.py:38

        color = None
        width = None
        height = None
        scale = None
        endian = None

        header = file.readline().rstrip()
        if header.decode("ascii") == "PF":
            color = True
        elif header.decode("ascii") == "Pf":
            color = False
        else:
            raise Exception("Not a PFM file: " + path)

        dim_match = re.match(r"^(\d+)\s(\d+)\s$", file.readline().decode("ascii"))
        if dim_match:
            width, height = list(map(int, dim_match.groups()))
        else:
            raise Exception("Malformed PFM header.")

        scale = float(file.readline().decode("ascii").rstrip())
        if scale < 0:
            # little-endian
            endian = "<"
            scale = -scale
        else:
            # big-endian
            endian = ">"

        data = np.fromfile(file, endian + "f")
        shape = (height, width, 3) if color else (height, width)

        data = np.reshape(data, shape)
        data = np.flipud(data)

        return data, scale

View on GitHub (pinned to ed85cd1e25)

Solutions

1. Inspect the first two lines of the file (e.g. head -c 64 file.pfm) and confirm the format 'W H '
2. Re-export or re-download the PFM from its source
3. If you control the writer, write the header with '%d %d\n' as write_pfm does

Example fix

# before
# file contains 'PF\n1024 768' (no trailing space/newline) 
# after
# rewrite header properly:
with open(p, 'wb') as f:
    f.write(('PF\n%d %d\n' % (w, h)).encode())

import re
with open(path, 'rb') as f:
    assert f.readline().strip() in (b'PF', b'Pf')
    assert re.match(rb'^(\d+)\s(\d+)\s$', f.readline()), 'malformed PFM dims'

try:
    img = read_pfm(path)
except Exception as e:
    if 'Malformed PFM header' in str(e):
        img = repair_or_reconvert(path)
    else:
        raise

When it happens

Trigger: Calling read_pfm on a PFM whose dimension line is missing, has non-numeric tokens, extra fields, or a truncated file where the second line is empty.

Common situations: Corrupted or hand-edited PFM files; files written by tools that omit the trailing whitespace or use different separators; partially downloaded datasets.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Not a PFM file:
• Image dtype must be float32.
• Malformed PFM header.
• Image dtype must be float32.
• Image must have H x W x 3, H x W x 1 or H x W dimensions.

AI-assisted analysis of lllyasviel/ControlNet@ed85cd1e25 (2026-08-27). Data as JSON: /api/errors/6b6ed3f5f33532b5. Report an issue: GitHub.