Inverse text problem found by Viewerdebugging

[Tangzy7]

I used Viewerdebugging and used "Recog Blob" to classify each Blob. I just found that some blobs are input as white-on-black text. However,some are black-on-white text. See the 2 images. The white-on-black text cannot be recognized correctly

[amitdo]

It looks like you are trying to OCR vertical (Chinese / Japanese) text.
#627 (comment)

[zdenop]

This is a know behavior - for tesseract 4 and above you need to use black on white (or dark on light) images
https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#inverting-images