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https://issues.apache.org/jira/browse/TIKA-3286?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17278296#comment-17278296
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Peter Kronenberg commented on TIKA-3286:
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Well, it's a marginal improvement. But I still feel that the Tesseract message
is misleading and not very user friendly. This is what I get:
{code:java}
Please make sure the TESSDATA_PREFIX environment variable is set to your
"tessdata" directory.
Failed loading language 'abc'
Tesseract couldn't load any languages!
Could not initialize tesseract.{code}
This is a condition that just requires a 1-line error message: "Language 'abc'
not found". Lines 1, 3 and 4 are just plain wrong. It found the tessdata
directory. It *can* load languages, just not the non-existent ones. And it
*did* initialize tesseract. It just couldn't load the language.
I realize that your philosophy is probably that you're just passing back what
Tesseract says, but I think Tika is trying to add a layer of user-friendlies to
it. So why not avoid passing any bad data to Tesseract in the first place?
Also, it's still not handling the script languages
> 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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