为什么会返回这个错误呢？

root@amd-3700-2gb ~/ocr_test # tesseract -l dan pdf.png out pdf
Tesseract Open Source OCR Engine v3.03 with Leptonica
Error opening data file /usr/local/share/tessdata/osd.traineddata
Please make sure the TESSDATA_PREFIX environment variable is set to the parent directory of your "tessdata" directory.
Failed loading language 'osd'
Tesseract couldn't load any languages!
Warning: Auto orientation and script detection requested, but osd language failed to load

语言列表

root@amd-3700-2gb ~/ocr_test # tesseract --list-langs
List of available languages (3):
eng
dan
dan-frak

输出为txt

这工作正常并将文本输出到out.txt

tesseract -l dan pdf.png out

输出PDF

这创造了out.pdf但也会返回提到的错误，并且 PDF 中的可搜索文本没有意义

tesseract -l dan pdf.png out pdf

错误信息很明确：它需要osd.traineddata文件。您可以从以下位置安装或下载 Tesseract 的方向和脚本检测数据：https://github.com/tesseract-ocr/tessdata https://github.com/tesseract-ocr/tessdata.