OCR is not working for images with dark background and light letters

[two way]

I've found a serious problem while I am testing with two images like below.

It is working well with first image which has light background and dark letters.

As you can see, the second image is the inverted color of the first image.

So I expected the two images to produce the same result.

However, none of the letters were properly detect in the second image.

Thanks for reading my suggestion.

Regards.

XueQing

[Zdenko Podobny]

Can you please first read documentation before posting to the forum?

You can start with https://github.com/tesseract-ocr/tessdoc/blob/master/ImproveQuality.md

Hint: you can have a look at leptonica pixAutoPhotoinvert()

https://github.com/DanBloomberg/leptonica/blob/f7a4bdc48f54c973e6b7c47b9181ac0ef0bd2089/src/pageseg.c#L2370

Zdenko

št 1. 4. 2021 o 16:00 two way <twowa...@gmail.com> napísal(a):

--
You received this message because you are subscribed to the Google Groups "tesseract-ocr" group.
To unsubscribe from this group and stop receiving emails from it, send an email to tesseract-oc...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/tesseract-ocr/73f9dbf2-751c-4b0e-9cbc-64889ae84d3bn%40googlegroups.com.

[two way]

Thanks for your quick response.

The problem occurred while I am using textfairy which is distributed as mobile application, and there was image pre-processing step in my opinion.

Is there any other android project alternative to textfairy?

[Zdenko Podobny]

if you have problem with textfairy, than report it to author:

https://github.com/renard314/textfairy

He updates app regularly (last update was 28. 3. 2021).

Zdenko

pi 2. 4. 2021 o 10:34 two way <twowa...@gmail.com> napísal(a):

To view this discussion on the web visit https://groups.google.com/d/msgid/tesseract-ocr/a869ae01-6eaa-4cd0-9fdd-39a7913bb262n%40googlegroups.com.