incorrectly detects orientation

[reubano]

I've noticed the orientation example doesn't distinguish between upside down/rightside up and clockwise/counter clockwise orientations.

reubano@tokpro [~]⚡ tesseract -psm 0 up.jpg - 
Orientation: 0
Orientation in degrees: 0
Orientation confidence: 0.23
Script: 1
Script confidence: 0.98

reubano@tokpro [~]⚡ tesseract -psm 0 down.jpg - 
Orientation: 2
Orientation in degrees: 180
Orientation confidence: 0.21
Script: 1
Script confidence: 0.61

with PyTessBaseAPI(psm=PSM.AUTO_OSD) as api:
    for path in ['up.jpg', 'down.jpg']:
        image = Image.open(path)
        api.SetImage(image)
        api.Recognize()
        it = api.AnalyseLayout()    
        print it.Orientation()

(0, 0, 2, 0.0)
(0, 0, 2, 0.0)

[sirfz]

Strange, just tested it with eurotext.tif (both original and flipped upside-down) and it output correct results:

with tesserocr.PyTessBaseAPI(psm=tesserocr.PSM.AUTO_OSD) as api:
    for image in ['eurotext.tif', 'eurotext_flipped.tif']:
        image = Image.open(image)
        api.SetImage(image)
        api.Recognize()
        it = api.AnalyseLayout()
        print it.Orientation()

Output:

(0, 0, 2, 0.013791237957775593)
(2, 0, 2, 0.013791237957775593)

[reubano]

My output

(0, 0, 2, 0.013791237957775593)
(0, 0, 2, 0.01034371554851532)

versions

reubano@tokpro [~]⚡ pip freeze | grep tesserocr
tesserocr==2.0.0

reubano@tokpro [~]⚡ tesseract --version
tesseract 3.04.00
 leptonica-1.73
  libgif 4.2.3 : libjpeg 9a : libpng 1.6.21 : libtiff 4.0.6 : zlib 1.2.8 : libwebp 0.5.0 : libopenjp2 2.1.0

fyi, tesserocr 2.0.1 isn't on pypi.

[sirfz]

Could you please share your images so I can properly test this?

[reubano]

Same one you linked

[sirfz]

2.0.1 doesn't have any changes to the source code so it won't differ from v2.0.0, main difference between our environments are the dependencies. Mine are:

$ tesseract --version
tesseract 3.04.00
 leptonica-1.72
  libjpeg 8d (libjpeg-turbo 1.3.0) : libpng 1.2.51 : libtiff 4.0.3 : zlib 1.2.8

Yours are more recent but I don't see why this should affect the output.

The example you're trying is based on the C API example here.

I'm using the packages provided in my default PPAs (Ubuntu 15.10) but I'll try to at least test with an updated compilation of leptonica and see if that changes anything. Would appreciate it if you can test on a different environment as well if possible and see if that gives different results.

[reubano]

I use macports which doesn't really let you downgrade a package. If it helps, I have Cython version 0.23.5.

[reubano]

I think the issue is with tesseract's (or maybe leptonica's) api. I modified code from nidaba to call the c-api directly and got similar results.

[sirfz]

Given that using the tesseract executable returns correct results, it's very possible that the problem is with the API interface. Certainly worth investigating.

[reubano]

I was able to downgrade to leptonica-1.71 and it appears to now work :).

[sirfz]

Glad you were able to pin the cause down. Still weird that you got the correct result with the tesseract executable though.

[reubano]

Go figure... hopefully someone smarter than me can figure that out.

[reubano]

Just a note for anyone else that the (macports) program tesseract-osd may also play a role in this. The downgraded leptonica complained that it was missing, so that could have been the cause.