Tesseract does not generate .lstmf for some images

[DavidHribek]

Hello,

I want to train tesseract on my own images (text lines). I copied all my images and texts into folder (image_name.[png/jpg], image_name.gt.txt).

Now i run this command:

make training MODEL_NAME=eng \ START_MODEL=eng \ MAX_ITERATIONS=100 \ PSM=7 \ TESSDATA=/path/to/tessdata \ GROUND_TRUTH_DIR=/path/to/folder/with/images/and/texts

It produces .lstmf, .box and .txt file for every image in the folder with message:

• tesseract /path/to/folder/with/images/and/texts/15_6_1617880355_1319177.png /path/to/folder/with/images/and/texts/15_6_1617880355_1319177 --psm 7 lstm.train Tesseract Open Source OCR Engine v4.1.0 with Leptonica Warning: Invalid resolution 0 dpi. Using 70 instead.

Then the training starts.

My problem: For some images second command does not produce .lstmf, .box, .txt files, but tesseract is still waiting for them, so training does not start.

Thanks for help.

[stweil]

Our problem: we don't know your images, but need one of those which don't work.

[DavidHribek]

For example from this image Tesseract never generates .lstmf, .box, .txt.

[stweil]

Thanks, confirmed.

[stweil]

There is an (unrelated) bug in src/ccmain/pagesegmain.cpp: read_unlv_file is called with a buggy name argument ("114025495-7830ed00-9875-11eb-8889-a9c9ea4003a7\000png.uzn").

[DavidHribek]

I tried to run training with less images including image "Benesov" mentioned above. Lstmf file was not generator for the "Benesov" image, it was skipped and training started. if I run training with all my images, training never starts.

[stweil]

Tesseract does not find a text box in this image. It tries to find lines, finds none (why?) and also does not use --psm 7 as a fallback and accept the whole image as a line.

Call stack:

#0  tesseract::line_edges (x=0, y=87, xext=210, uppercolour=1 '\001', bwpos=0x611000006a80 "", prevline=0x61c000000080, free_cracks=0x7fffffff88c0, outline_it=0x7fffffff8ce0)
    at ../../../src/textord/scanedg.cpp:185
#1  0x0000000001ca7615 in tesseract::block_edges (t_pix=..., block=0x60f000000138, outline_it=0x7fffffff8ce0) at ../../../src/textord/scanedg.cpp:99
#2  0x0000000001c5c805 in tesseract::extract_edges (pix=..., block=0x60f000000130) at ../../../src/textord/edgblob.cpp:330
#3  0x0000000001ebf79b in tesseract::Textord::find_components (this=0x7ffff183e5f0, pix=..., blocks=0x6020000064d0, to_blocks=0x7fffffff9c80)
    at ../../../src/textord/tordmain.cpp:224
#4  0x0000000001e9b2ef in tesseract::Textord::TextordPage (this=0x7ffff183e5f0, pageseg_mode=tesseract::PSM_SINGLE_LINE, reskew=..., width=210, height=88, binary_pix=..., 
    thresholds_pix=..., grey_pix=..., use_box_bottoms=false, diacritic_blobs=0x7fffffff9c60, blocks=0x6020000064d0, to_blocks=0x7fffffff9c80)
    at ../../../src/textord/textord.cpp:185
#5  0x0000000000b34cca in tesseract::Tesseract::SegmentPage (this=0x7ffff181a800, input_file=0x6060000033e0 "114025495-7830ed00-9875-11eb-8889-a9c9ea4003a7.png", 
    blocks=0x6020000064d0, osd_tess=0x0, osr=0x7fffffffa3a0) at ../../../src/ccmain/pagesegmain.cpp:172
#6  0x000000000058fc0d in tesseract::TessBaseAPI::FindLines (this=0x7fffffffdb40) at ../../../src/api/baseapi.cpp:2187
#7  0x0000000000591ea9 in tesseract::TessBaseAPI::Recognize (this=0x7fffffffdb40, monitor=0x0) at ../../../src/api/baseapi.cpp:837
#8  0x00000000005a12f9 in tesseract::TessBaseAPI::ProcessPage (this=0x7fffffffdb40, pix=0x606000003380, page_index=0, 
    filename=0x7fffffffe668 "114025495-7830ed00-9875-11eb-8889-a9c9ea4003a7.png", retry_config=0x0, timeout_millisec=0, renderer=0x0) at ../../../src/api/baseapi.cpp:1254
#9  0x00000000005a71fe in tesseract::TessBaseAPI::ProcessPagesInternal (this=0x7fffffffdb40, filename=0x7fffffffe668 "114025495-7830ed00-9875-11eb-8889-a9c9ea4003a7.png", 
    retry_config=0x0, timeout_millisec=0, renderer=0x0) at ../../../src/api/baseapi.cpp:1217
#10 0x00000000005a3102 in tesseract::TessBaseAPI::ProcessPages (this=0x7fffffffdb40, filename=0x7fffffffe668 "114025495-7830ed00-9875-11eb-8889-a9c9ea4003a7.png", 
    retry_config=0x0, timeout_millisec=0, renderer=0x0) at ../../../src/api/baseapi.cpp:1070
#11 0x00000000004e635a in main (argc=6, argv=0x7fffffffe398) at ../../../src/api/tesseractmain.cpp:782

[stweil]

@DavidHribek, you could try removing the left black border from the image. The image can also be cropped below the text. Maybe one of those modifications might fix the problem.

[amitdo]

Tesseract in non training mode will also fail.

This is a know issue.

Try this command (ImageMagick):

convert img1.png -bordercolor White -border 10x10 img2.png