tesseract does not recognize letters of good quality

[Golddouble]

Environment

• Tesseract Version: 4.0.0-2
• Platform: Linux mx 4.19.0-20-amd64 SMP Debian 4.19.235-1 (2022-03-17) x86_64 GNU/Linux

My observation is about the following image:

Current Behavior:

In

tessarect does not recognize the following letters:

Expected Behavior:

I had expected, that tesseract would recognize this letters, because the quality of this letters is quite good.
I am just surprised, that it does not recognize them. What do I miss?
Do you have an explanation for this behaviour?

Would be very interested in an answer.

Thank you.

[stweil]

Either try to preprocess the image before running (latest, not a rather old) Tesseract. Or use a different software.

Tesseract works best with black (or at least grey) letters on white background. It can also handle inverted line images with white letters on black background. The current code does not handle lines with a mix of normal and inverted text.

Generally layout and line detection with algorithms seems to be difficult, and Tesseract does not work nearly perfectly for complex layouts. Other modern software uses trained neural networks for layout detection and might give better results. Tesseract still misses that, mainly because of missing developer resources.

[stweil]

Some of the problems reported here might be fixed with draft pull request #3857:

$ tesseract https://user-images.githubusercontent.com/13977359/177207586-20a5f497-8ece-486b-ae0d-2d515fe7a226.jpeg - -l tessdata_fast/script/Latin -c preprocess_graynorm_mode=1
Estimating resolution as 361
1
Verschiedene Freizeitaktivitäten kennen und beschreiben

----- > DW: Die Schrifterkennung muss verbessert werden: hochgestellte Zahlen werden nicht erkannt.
Text in farbigen Kästen weren nicht erkannt. Fette Schrift wird nicht erkannt.

Les loisirs: stress ou détente?

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[Golddouble]

Is this with Tess a er e act 5?

[stweil]

No, it is with Tesseract 5. 😄