Read PFM format in python

Question

I want to read pfm format images in python. I tried with imageio.read but it is throwing an error. Can I have any suggestion, please?

img = imageio.imread(\'im

Answer 1

img = imageio.imread('image.pfm')

will just do it. For easy use it can be converted to numpy array.

img = numpy.asarray(img)

Answer 2

I am not at all familiar with Python, but here are a few suggestions on reading a PFM (Portable Float Map) file.

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Option 1

The ImageIO documentation here suggests there is a FreeImage reader you can download and use.

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Option 2

I pieced together a simple reader myself below that seems to work fine on a few sample images I found around the 'net and generated with ImageMagick. It may contain inefficiencies or bad practices because I do not speak Python.

#!/usr/local/bin/python3
import sys
import re
from struct import *

# Enable/disable debug output
debug = True

with open("image.pfm","rb") as f:
    # Line 1: PF=>RGB (3 channels), Pf=>Greyscale (1 channel)
    type=f.readline().decode('latin-1')
    if "PF" in type:
        channels=3
    elif "Pf" in type:
        channels=1
    else:
        print("ERROR: Not a valid PFM file",file=sys.stderr)
        sys.exit(1)
    if(debug):
        print("DEBUG: channels={0}".format(channels))

    # Line 2: width height
    line=f.readline().decode('latin-1')
    width,height=re.findall('\d+',line)
    width=int(width)
    height=int(height)
    if(debug):
        print("DEBUG: width={0}, height={1}".format(width,height))

    # Line 3: +ve number means big endian, negative means little endian
    line=f.readline().decode('latin-1')
    BigEndian=True
    if "-" in line:
        BigEndian=False
    if(debug):
        print("DEBUG: BigEndian={0}".format(BigEndian))

    # Slurp all binary data
    samples = width*height*channels;
    buffer  = f.read(samples*4)

    # Unpack floats with appropriate endianness
    if BigEndian:
        fmt=">"
    else:
        fmt="<"
    fmt= fmt + str(samples) + "f"
    img = unpack(fmt,buffer)

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Option 3

If you cannot read your PFM files in Python, you could convert them at the command line using ImageMagick to another format, such as TIFF, that can store floating point samples. ImageMagick is installed on most Linux distros and is available for macOS and Windows:

magick input.pfm output.tif