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.