Java OpenCV + Tesseract OCR “code” regocnition

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I'm trying to automate a process where someone manually converts a code to a digital one.

Then I started reading about OCR. So I installed tesseract OCR and tried it on some images. It doesn't even detect something close to the code.

I figured after reading some questions on stackoverflow, that the images need some preprocessing like skewing the image to a horizontal one, which can been done by openCV for example.

Now my questions are:

• What kind of preprocessing or other methods should be used in a case like the above image?
• Secondly, can I rely on the output? Will it always work in cases like the above image?

I hope someone can help me!