OSD not working for rotated image, but working for same image after deskew

[Layneww]

Environment

• Tesseract Vetesseract:
  4.0.0-beta.1-270-g5a56
  leptonica-1.76.0
  libjpeg 9c : libpng 1.6.34 : libtiff 4.0.9 : zlib 1.2.11
  Found AVX2
  Found AVX
  Found SSErsion

• Commit Number:

• Platform:
  Macbook Air
  Darwin 17.6.0 Darwin Kernel Version 17.6.0: Tue May 8 15:22:16 PDT 2018; root:xnu-4570.61.1~1/RELEASE_X86_64 x86_64

Current Behavior:

I refer to #1463 for the command line.

tesseract image-rotated-270.png stdout --tessdata-dir <my tessdata dir> --psm 0 --oem 0 -l osd

The text on the image is like a label, printed text but the text is not much. Around 5 lines, each line with averge 15 Thai characters.
The output is

Warning. Invalid resolution 0 dpi. Using 70 instead.
Too few characters. Skipping this page
Error during processing.

However, when I rotated it back to the horizontal direction manually, then use the same command line. I got this result,

Warning. Invalid resolution 0 dpi. Using 70 instead.
Page number: 0
Orientation in degrees: 0
Rotate: 0
Orientation confidence: 0.54
Script: Latin
Script confidence: 2.22

BTW, the script type has a high error rate. I have another Thai pic, and it predicts Cyrillic.

Update:
For one picture, I tried both the command line and the API (using a Python wrapper called tesserocr), the command line --psm 0 --oem 0 -l osd outputs 'too few characters. skipping', while the api can give the orientation result.
Besides, tesseract can give output of the text on this picture using tesseract <picture name> stdout -l tha+eng

Expected Behavior:

Since they are actually the same picture, tesseract should perform the same connected component analysis on both. Thus it should not return too few characters.

Update:
It should return the same orientation result since the command line and the api are equivalent.

Suggested Fix:

NA

[amitdo]

I don't know why it does not warn with the second image.

In any case (with or without warning), less than 50 characters is too little for the OSD feature to reliably detect script and orientation.

[tailsu]

There is the parameter min_characters_to_try which governs the cutoff mentioned by @amitdo . By default it's 50.

$ tesseract --print-parameters | fgrep characters
...
min_characters_to_try	50	Specify minimum characters to try during OSD

[suravijayjilla]

Hi,

Is this possible to change that cutoff value.
I am facing the same issue, I need to change that value and try to rotate the image.

[amitdo]

@Layneww, without an image we can't test the reported issue and thus can't help you.