Tesseract 4.0 hangs when processing a particular image

[lewislun]

Environment

• Tesseract Version: tesseract 4.0.0-beta.1
  leptonica-1.75.3
  libgif 5.1.4 : libjpeg 8d (libjpeg-turbo 1.5.2) : libpng 1.6.34 : libtiff 4.0.9 : zlib 1.2.11 : libwebp 0.6.1 : libopenjp2 2.3.0
• Platform: Ubuntu 18.04.1 LTS

Current Behavior:

hangs when running the following command:
tesseract failed-image.jpeg output.txt

output message:

Tesseract Open Source OCR Engine v4.0.0-beta.1 with Leptonica
Warning. Invalid resolution 0 dpi. Using 70 instead.
Estimating resolution as 207

Tesseract does not stop nor give any message after that.
other images work fine, i only have trouble processing this particular image.
I have found that the image after processed by tesseract (or leptonica?) is weird, dont know if it is related.

failed-image.jpeg: https://drive.google.com/open?id=1HsgCbtuNpgf_XxzjkekXU9-uuiWDsV0H
tessinput.tif: https://drive.google.com/open?id=1sE8Nn5rykSWPT6PMF3nFSonPMT9y-H61

Expected Behavior:

Tesseract should either give an error message or finish ocr on the image even if the image quality is bad.

[zdenop]

1. Your tesseract version is outdated.
2. jpeg is not suitable format for OCR (jpeg compression artifacts)
3. Your input is not suitable for tesseract binarization (Otsu) algorithm (result you see in tessinput.tif). Did you read ImproveQuality wiki?

[stweil]

The problem also exists with latest code. This might be another example for issue #2196.

[stweil]

Tesseract hangs in an endless loop here:

(gdb) i s
#0  tesseract::ColPartitionGrid::FindPartitionPartners (this=0x555557d2ea90) at ../../../../../src/textord/colpartitiongrid.cpp:1190
#1  0x00005555555ffdc0 in tesseract::ColumnFinder::FindBlocks (this=0x555557d2e950, pageseg_mode=tesseract::PSM_AUTO, scaled_color=0x0, scaled_factor=-1, 
    input_block=0x555557d1ed60, photo_mask_pix=0x5555559592d0, thresholds_pix=0x555555958550, grey_pix=0x5555559585a0, pixa_debug=0x7ffff69159f0, blocks=0x7fffffffd130, 
    diacritic_blobs=0x7fffffffd208, to_blocks=0x7fffffffd210) at ../../../../../src/textord/colfind.cpp:432
#2  0x00005555555ca938 in tesseract::Tesseract::AutoPageSeg (this=0x7ffff68f2010, pageseg_mode=tesseract::PSM_AUTO, blocks=0x555555955720, to_blocks=0x7fffffffd210, 
    diacritic_blobs=0x7fffffffd208, osd_tess=0x0, osr=0x7fffffffd5d0) at ../../../../../src/ccmain/pagesegmain.cpp:226
#3  0x00005555555ca4d7 in tesseract::Tesseract::SegmentPage (this=0x7ffff68f2010, input_file=0x55555595ed90, blocks=0x555555955720, osd_tess=0x0, osr=0x7fffffffd5d0)
    at ../../../../../src/ccmain/pagesegmain.cpp:139
#4  0x0000555555584380 in tesseract::TessBaseAPI::FindLines (this=0x5555558ce280 <main::api>) at ../../../../../src/api/baseapi.cpp:2090
#5  0x000055555557f7cd in tesseract::TessBaseAPI::Recognize (this=0x5555558ce280 <main::api>, monitor=0x0) at ../../../../../src/api/baseapi.cpp:835
#6  0x0000555555580fa6 in tesseract::TessBaseAPI::ProcessPage (this=0x5555558ce280 <main::api>, pix=0x5555559583c0, page_index=0, 
    filename=0x7fffffffe744 "issue/2288/failed-image.jpeg", retry_config=0x0, timeout_millisec=0, renderer=0x555555950840) at ../../../../../src/api/baseapi.cpp:1228
#7  0x0000555555580d3a in tesseract::TessBaseAPI::ProcessPagesInternal (this=0x5555558ce280 <main::api>, filename=0x7fffffffe744 "issue/2288/failed-image.jpeg", 
    retry_config=0x0, timeout_millisec=0, renderer=0x555555950840) at ../../../../../src/api/baseapi.cpp:1186
#8  0x00005555555806d1 in tesseract::TessBaseAPI::ProcessPages (this=0x5555558ce280 <main::api>, filename=0x7fffffffe744 "issue/2288/failed-image.jpeg", retry_config=0x0, 
    timeout_millisec=0, renderer=0x555555950840) at ../../../../../src/api/baseapi.cpp:1076
#9  0x000055555557b3ae in main (argc=3, argv=0x7fffffffe498) at ../../../../../src/api/tesseractmain.cpp:745

Issue #2196 has a different stack, so it looks like we have two issues with images causing an endless loop in the layout detection.

[zdenop]

Yes, endless loop is problem - that is the reason I keep issue open.
But points 2. and 3. can help to avoid problem or if there is no issue with endless loop, OCR will not produce expected results.

[amitdo]

The main issue here is Tesseract's binarization method.

I used GIMP's thresholding (60-255) to produce this image.

output with best:

 
 

Great Daddy, 2014 ELE

Acrylic on canvas
200 x 300 cm

 
Error during processing.

[zdenop]

@amitdo : I do not think the main issue is Tesseract's binarization method... It works good in most of cases (see e.g. 2264) - but not it all. I expect if we replace it with something else, we will get similar reports with other kind of images.

Anyway patch for automatic selection best of binarization algorithm is welcomed ;-)

And of course infinite loop in tesseract should be fixed too.

[stweil]

Automatic selection would be great, but a first step could be to offer some binarization algorithms, so the user has a choice (command line option or config parameter).

[chintler]

I'm facing this issue too. Are there any updates or workarounds that I can try, including what @stweil suggested?

[Ra-Na]

Same here. Ubuntu 18.04, tesseract 4.0.0-beta.1.