Install OCRmyPDF on ubuntu
$ apt install ocrmypdf
$ ocrmypdf --version
6.1.2
Install the Chinese language pack (Chinese horizontal)
$ apt-get install tesseract-ocr-chi-sim
image to pdf
$ apt-get install img2pdf
Query available language packs
$ apt-cache search tesseract-ocr
Identification picture 64533220-b006-4182-b2b9-9bc621d797e4.jpg
img2pdf 64533220-b006-4182-b2b9-9bc621d797e4.jpg | ocrmypdf -l chi_sim - myfile.pdf