wrong recognition of small lines or points

[Filippo Riccio]

Hallo everybody,

I am testing Tesseract to recognize the characters in the attached Picture.

I created a traineddata with a small number of characters.

My Problem is that Tesseract recognizes as character also the small lines at the left of the first 0 and

under J. Precisely, the recognized text is F0002HNJH2UF

How can I avoid it? It is possible to fix the minimal size of characters?

Thank you in advance.

[Meh Hem]

The is definitely tesseract api configs for that :

textord_heavy_nr = 0 (0 default, 1 is very aggressive)

textord_max_noise_size

However I would simply use opencv to remove any blob with a vertical height of less than desired. 

[Stephen Lambie]

What function of opencv would you use to do that?

[Meh Hem]

Some links:

http://stackoverflow.com/questions/10238765/contours-opencv-how-to-eliminate-small-contours-in-a-binary-image

http://stackoverflow.com/questions/15628739/c-opencv-eliminate-smaller-contours

http://www.pyimagesearch.com/2015/02/09/removing-contours-image-using-python-opencv/

I was entirely impressed by the bounding box method of contour removal, but I did find success with findContours: 

Just filter which are the contours you want to lose (in your case using  height I would say) and replace the black pixels with white.

http://docs.opencv.org/2.4/doc/tutorials/imgproc/shapedescriptors/find_contours/find_contours.html

Looking at that text I would also consider doing some morphology to make the characters a bit stronger. 

I hope this helps