How to convert RGB values from .txt file to display an image in Python

Question

I have a .txt file which contains RGB values, when I open and read the files, the pixel values are in str format. How do I convert these values to display an image in python. image.

This is the when I tried reading the values. They are all in a string format.

Edit: You can find the link for the file here https://drive.google.com/file/d/1mAxlcMj_SVeK0axJhbPJqO4k_egJoYli/view?usp=sharing

Answer 1

This does the trick quite simply:

#!/usr/bin/env python3

import re
import numpy as np
from PIL import Image
from pathlib import Path

# Open image file, slurp the lot
contents = Path('image.txt').read_text()

# Make a list of anything that looks like numbers using a regex...
# ... taking first as height, second as width and remainder as pixels
h, w, *pixels = re.findall(r'[0-9]+', contents)

# Now make pixels into Numpy array of uint8 and reshape to correct height, width and depth
na = np.array(pixels, dtype=np.uint8).reshape((int(h),int(w),3))

# Now make the Numpy array into a PIL Image and save
Image.fromarray(na).save("result.png")

---

If you want to write the output image with OpenCV instead of with PIL/Pillow, change the last line above to the following so it does RGB->BGR reordering and uses cv2.imwrite() instead:

# Save with OpenCV instead
cv2.imwrite('result.png', na[...,::-1])

---

If you want to write a PPM file (compatible with Photoshop, GIMP, OpenCV, PIL/Pillow and ImageMagick), without using PIL/Pillow or OpenCV or any extra libraries, and have it around 1/4 the size of your original file, you can write it very simply in binary by replacing the last line above with:

# Save "na" as binary PPM image
with open('result.ppm','wb') as f:
   f.write(f'P6\n{w} {h}\n255\n'.encode())
   f.write(na.tobytes())

---

In fact, you don't need any Python, you can do it directly at the command line in Terminal if you write a NetPBM file that can be read by Photoshop, GIMP, PIL/Pillow

awk 'NR==1{$0="P3\n" $2 " " $1 "\n255"} {gsub(/,/,"\n")} 1' image.txt > result.ppm

That script basically "massages" your first line so it goes from this:

418 870
... rest of your data ...

to this:

P3
870 418
255
... rest of your data ...