... DXFView, image2pdf, PDFtk, xpdfbin (pdftotext, pdfimages,...). Ups, quite a lot, I wasn't aware of it. 8) So, my recommendation is: For test purposes, split one of those affected tiff, OCRing (with the API) all single tiffs, pngs or ppm/pbm (built one searchable pdf) and compare the results. ...