Tesseract 4.1 incorrect symbol bounding rectangle coordinates

[romanchetto]

Hello everyone.

After upgrading from tesseract v.4.0 to 4.1 I have faced with the next issue: sometimes symbols in words are swapped. I've found out that returned text value and bounding rectangle from word result iterator are OK. But when I collect problem word symbols from symbol iterator, I've found out that X-coordinate and width are sometimes incorrect:

On this screenshot you can see that symbol "m" goes before "A" in the word "American", and its width is twice longer that average symbol length in the word

Tesseract 4.1 release notes says: "Fix for bounding box problem." Maybe this fix somehow relates to this issue.

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Environment

• Tesseract Version: release 4.1.0 from 07 July 2019
• Commit Number: 5280bbc
• Platform: Windows 10 x64
• Language: eng., tessdata_fast
• PageSegMode: 1 and 6
• Dependencies: leptonica 1.78.0, giflib 5.2.1, libtiff 4.0.10, zlib 1.2.11, libpng 1.6.37, libjpeg 9c, openjpeg 2.3.0, libwebp: 0.5.2
• Issue image:
  

Current Behavior:

Incorrect symbol bounding rectagle value, if order by X-coordinate symbols are swapped

Expected Behavior:

All symbol bounding rectangle values are correct. If order by X-coordinate word symbols are in corresponding order, like in word text value

[stweil]

@noahmetzger, could you please test that with the latest code?

[noahmetzger]

With the new algorithm its definitly better, but still far away from perfect.

Version 4.1

Version 5

[romanchetto]

Hello @noahmetzger , @stweil . Is version 5 - current "master" and 4.1 - July release? By the way, could you please try on version 4.0 to compare with 4.1 and 5? On version 4.0 I don't face with this issue

[noahmetzger]

If we are talking about the commits
4.1: 5280bbc
and
4.0: c69859c

for me the bounding boxes are completely identical

[romanchetto]

@noahmetzger , Sorry, under 4.0 I have meant Release 4.0.0 from 29 October 2018, commit 5131699

[noahmetzger]

@romanchetto your right 4.0 had better bounding boxes compared to 4.1.

compared to 5.0 its hard to say which one is better.
But look for yourself. Here is the outcome of 4.0

[stweil]

I tried to bisect this. It looks like the regression was introduced by commit ce88adb.

[romanchetto]

@stweil , @noahmetzger, Thank you for your help. I will think how to handle this from my side, or just wait for 5.0 release.

[shermanrxie]

We got the same issue, and the result of 4.1 is more worse then 4.0. We plan rollback to version 4.0. And hope it can be resolved in 5.0.

[zdenop]

@shermanrxie : your comment with testing image is useless, and hope that somebody fit it in 5.0 without testing case has no meaning.