做個筆記，幫助複查
>tesseract --version
tesseract v4.0.0-beta.1.20180608
leptonica-1.76.0
libgif 5.1.4 : libjpeg 8d (libjpeg-turbo 1.5.3) : libpng 1.6.34 : libtiff 4.0.9 : zlib 1.2.11 : libwebp 0.6.1 : libopenjp2 2.2.0
版本是tesseract v4.0.0-beta.1.20180608
>tesseract--help-extra
Usage:
tesseract --help | --help-extra | --help-psm | --help-oem | --version
tesseract --list-langs [--tessdata-dir PATH]
tesseract --print-parameters [options...] [configfile...]
tesseract imagename|imagelist|stdin outputbase|stdout [options...] [configfile...]
OCR options:
--tessdata-dir PATH Specify the location of tessdata path.
--user-words PATH Specify the location of user words file.
--user-patterns PATH Specify the location of user patterns file.
-l LANG[+LANG] Specify language(s) used for OCR.
-c VAR=VALUE Set value for config variables.
Multiple -c arguments are allowed.
--psm NUM Specify page segmentation mode.
--oem NUM Specify OCR Engine mode.
NOTE: These options must occur before any configfile.
Page segmentation modes:
0 Orientation and script detection (OSD) only.
1 Automatic page segmentation with OSD.
2 Automatic page segmentation, but no OSD, or OCR.
3 Fully automatic page segmentation, but no OSD. (Default)
4 Assume a single column of text of variable sizes.
5 Assume a single uniform block of vertically aligned text.
6 Assume a single uniform block of text.
7 Treat the image as a single text line.
8 Treat the image as a single word.
9 Treat the image as a single word in a circle.
10 Treat the image as a single character.
11 Sparse text. Find as much text as possible in no particular order.
12 Sparse text with OSD.
13 Raw line. Treat the image as a single text line,
bypassing hacks that are Tesseract-specific.
OCR Engine modes:
0 Legacy engine only.
1 Neural nets LSTM engine only.
2 Legacy + LSTM engines.
3 Default, based on what is available.
Single options:
-h, --help Show minimal help message.
--help-extra Show extra help for advanced users.
--help-psm Show page segmentation modes.
--help-oem Show OCR Engine modes.
-v, --version Show version information.
--list-langs List available languages for tesseract engine.
--print-parameters Print tesseract parameters.
對於單個字符的識別
在做測試的過程中發現對於字符串的識別，使用默認的方式就可以做出識別
tesseract img.png output
查閱之後，可以在命令後面添加選項的方式，增強識別的效果
--psm NUM Specify page segmentation mode.
--oem NUM Specify OCR Engine mode.
例如識別單個字符
--psm NUM Specify page segmentation mode.
10 Treat the image as a single character.
tesseract img.png output --psm 10
