Tesseract is now included better thresholding (binarization) in v5. Users that have
thresholding issues should try that first. If we find further problems
this can be brought back as a plugin.
These files were contributed when the project license was GPLv3. On
discussion, all known authors of these files agreed to place them
under MIT license.
See https://github.com/jbarlow83/OCRmyPDF/issues/600