Check if a PDF file is a scanned one

Question

What is the best way to programmatically check if a PDF file is a totally scanned one? I do have iText and PDFBox at my disposal. I can check if a pdf file contains text or

Answer 1

find ./ -name "*.pdf" -print0 | xargs -0 -I {} bash -c 'export file="{}"; if [ $(pdffonts "$file" 2> /dev/null | wc -l) -lt 3 ]; then echo "$file"; fi'

Explanation: pdffonts file.pdf will show more than 2 lines if pdf contains text. Outputs filenames of all pdf files that don't contain text, so are scanned PDFs.