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https://issues.apache.org/jira/browse/TIKA-3286?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17278027#comment-17278027
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Peter Kronenberg commented on TIKA-3286:
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It does, but as you can see in my screenshot. it issues 4 lines of messages
that also imply that it can't find the Tessdata directory at all and can't load
any languages. And since there is no return code to check, it means Tika would
have to check the contents of stdout on every Tesseract call. I think it's
much easier to just check that the files exist before even calling Tesseract.
And there might be other messages that Tesseract issues that aren't necessary
errors, so we wouldn't want to throw an exception just because Tesseract
printed something to stdout. It would be different if this was more of an api
rather than just essentially calling Tesseract as a command-line program
> Tika does not issue an error when language file doesn't exist; not supporting
> script files
> ------------------------------------------------------------------------------------------
>
> Key: TIKA-3286
> URL: https://issues.apache.org/jira/browse/TIKA-3286
> Project: Tika
> Issue Type: Improvement
> Reporter: Peter Kronenberg
> Priority: Major
> Attachments: list-lang.png, nolang.png, script.png
>
>
> Tika uses a regular expression to validate the language string, assuming it
> is set of ISO-639-2 language code separated by plus signs. However, Script
> files (in the _script_ directory) can have any arbitrary name, with the only
> rule being that they start with a capital letter. The scripts were
> introduced in 4.0.0, [https://github.com/manisandro/gImageReader/issues/323]
>
> In addition, if the user specifies an invalid language (i.e., the string
> matches the regular expression, but there is no corresponding language file
> in Tessdata), no error message is issued. Tesseract issues some very ugly
> and misleading messages which simply assume that you haven't set the
> _tessdata_ directory correctly, but they are not captured by Tika (and not
> sure they would be appropriate anyway). Tika just blindly calls Tesseract
> but then doesn't get any output back.
> !nolang.png!
> I suggest parsing the language string by the plus sign and not doing any
> other validating on the string, but instead, actually checking to see that
> the file exists in either _tessdata_ or _tessdata/script_.
> If any of them don’t exists, then throw an exception, similar to what is done
> now when the language doesn't match the regular expression.
> I've started to prototype this.
>
> Later: I'm trying to clarify how the scripts are intended to be used. The
> page referenced above as well as
> [https://github.com/tesseract-ocr/tesseract/blob/master/doc/tesseract.1.asc#LANGUAGES
>
> |https://github.com/tesseract-ocr/tesseract/blob/master/doc/tesseract.1.asc#LANGUAGES]imply
> that the _-l_ option accepts the name of a language or script. I assumed it
> would look in _tessdata_ first and if not found, would look in
> _tessdata/script_. But it seems you have to enter the path.
> !script.png!
> _tesseract --list-lang_ displays them this way
> !list-lang.png!
> so it clearly knows about the _script_ directory. But it expects the user to
> know it as well. Not sure if we want to make Tika work more friendly
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