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https://issues.apache.org/jira/browse/TIKA-3361?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17325904#comment-17325904
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Peter Kronenberg edited comment on TIKA-3361 at 4/20/21, 3:25 PM:
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Yes, theoretically, you're correct. You could argue that Best should mean if
there is just 1 Unmapped character, than we should use OCR. But the idea is to
still balance performance with accuracy and just do it a little more
intelligently. If there user wanted to just OCR everything, then he should
just set OCR Strategy to OCR_Only.
The problem here is with the word Best. It's not really Best. It's just
_Fast_ and _Better but not as Fast._ So perhaps we need to come up with a
better keyword
was (Author: peterkronenberg):
Yes, theoretically, you're correct. You could argue that Best should mean if
there is just 1 Unmapped character, than we should use OCR. But the idea is to
still balance performance with accuracy and just do it a little more
intelligently. If there user wanted to just OCR everything, then he should
just set OCR Strategy to OCR_Only.
The problem here is with the word Best. It's not really Best. It's just
_Fast_ and _Better but not as Fast._ So perhaps we need to come up with a
better _keyword_
> Improve intelligence of OCRStrategy=AUTO
> -
>
> Key: TIKA-3361
> URL: https://issues.apache.org/jira/browse/TIKA-3361
> Project: Tika
> Issue Type: Improvement
>Reporter: Peter Kronenberg
>Priority: Major
>
> Didn’t get a whole lot of feedback on the mailing list, so here’s my attempt
> at improving OCRStrategy=Auto
> Currently, this strategy performs the following test
> {code:java}
> if (totalCharsPerPage < 10 || unmappedUnicodeCharsPerPage > 10) {
> doOCROnCurrentPage(AUTO);
> }
> {code}
> I added a way to change the new numbers involved: the threshold for the total
> characters per page (below which, we OCR the page), and the threshold for
> unmapped characters (above which we OCR the page)
> My main concern is with the unmapped characters. OCR adds a lot of overhead,
> which might not be necessary for simply a few unmapped characters
> I added a new config, *OCRStrategyAuto*, which is only used if
> OCRStrategy=AUTO. Its format is
> {code:java}
> ocrStrategyAuto = best|fast|m[%], n
> {code}
> ‘best’ and ‘fast’ are shortcuts. More later
> m, n – m is the threshold for the number of unmapped characters per page. It
> can also be specified as a percentage. So, m=20 means if your page has more
> than 20 unmapped characters, it will OCR. m=20% means if the unmapped
> characters are more than 20% of the total characters, then it will OCR.
> n is the threshold for the total number of characters on the page. n does not
> need to be specified and defaults to 10
> {code:java}
> 20
> {code}
> is equivalent to
> {code:java}
> 20, 10
> {code}
> *best* is shorthand for *20,10*
> {code:java}
> best
> {code}
> is equivalent to
> {code:java}
> 20, 10
> {code}
> *best* is the default and is equivalent to the current behavior
> *fast* is a shortcut for *10%, 10*, which will avoid OCR unless the number
> of unmapped characters is greater than 10%
> {code:java}
> fast
> {code}
> is equivalent to
> {code:java}
> 10%, 10
> {code}
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