Software or method to batch invert b/w images

Question

I have directories of 100-500 small black & white image files (jpg) that I need to batch invert, from white text on black to black text on white. They will then be input to tesseract-ocr.
I am looking for software or some method on Ubuntu 16.04 to do this. Maybe tesseract has such a function?

I found this: How to invert colors in multiple images using Gimp in terminal? which seems to be the right idea, but it is an old answer and the link is dead. When I searched on "Batch Image Manipulation Plugin" I found it but only for Windows (I only have Gimp installed on Ubuntu).

I have seen some solutions using imagemagick, but it doesn't seem to run on my system, so I would rather avoid those for now.

This doesn't seem so difficult, but so far I haven't found anything that can do batch processing. I am not a Linux expert so if it isn't a GUI or command line solution I may need a detailed instruction.

A Windows 7 solution may be ok if no other option.

I am looking for a no-cost solution if possible.

Answer 1

If you are happy with python and have PIL or Pillow installed then the answers to https://stackoverflow.com/questions/2498875/how-to-invert-colors-of-image-with-pil-python-imaging is a way to go.

You can add in a glob to find all of your images.

Something like: from PIL import Image from PIL import ImageOps from glob import glob import os os.chdir('Documents/') # Obviously this needs to be the top directory of your image tree file_list = glob("**/*.jpg", recursive=True) # Get the filenames outdir = "Converted" # You can set this to what you like for fname in file_list: # For each filename image = Image.open(fname) # Read it as an image image=image.convert('L') # Make sure it is gray-scale image=ImageOps.invert(image) # invert it newname = os.path.join(outdir, os.path.split(fname)[-1]) # Create a new name print("Saving Inverted", fname, "as", newname) image.save(newname) # Save it

Answer 2

ImageMagick is my/the goto for all batch processing of images.

• Open Source
• Cross Platform

Using with the Linux find command, (Warning: This will invert in-place every image it finds):

cd the_top_dir_of_your_image_tree
find . -name "*.jpg" -exec magick mogrify -negate {};

Note that some versions of ImageMagick install convert and mogrify as distinct tools while others have a magick with sub-commands.