问题
I am trying to recognize one line of handwritten digits. Currently I do some preprocessing with Python and OpenCV, split the image into connected components and feed these components to Tesseract with PSM=10 (page segmentation mode, 10 is "treat the image like a single character") and character whitelist restricted to "0123456789". I expect Tesseract to return garbage where my connected component segmentation fails and to return exactly one digit when my segmentation succeeds. Tesseract often returns nothing at all.
I have tried both pytesseract and python-tesseract as a Tesseract interface for Python. Pytesseract works by locating the executable tesseract.exe, running it with suitable parameters from the shell and collecting the answer. This is how I found out about my problem. After that, I tried python-tesseract, which implements a full-blown C API. Naturally, the result was the same.
Below is a sample of 5 images I fed into Tesseract separately (I've also uploaded the same images as separate files here):
I get 1,*,4,*,* on these images, * meaning that Tesseract returned only whitespace.
With other page segmentation modes, I get the following:
PSM_SINGLE_CHAR: 1*4**
PSM_SINGLE_BLOCK_VERT_TEXT: **43*
PSM_CIRCLE_WORD: 11***
PSM_SINGLE_LINE: 11491
PSM_AUTO: *****
PSM_SPARSE_TEXT: *****
PSM_SINGLE_WORD: 11499
PSM_AUTO_ONLY: *****
PSM_SINGLE_COLUMN: *****
PSM_SPARSE_TEXT_OS: *****
PSM_SINGLE_BLOCK: 11499
PSM_OSD_ONLY: *****
PSM_AUTO_OSD: *****
PSM_COUNT: 11499
Weirdly, when I run tesseract image.png image -l eng -psm 10 digits-only against these images, it returns *,*,4,9,*. (digits-only is tessedit_char_whitelist 0123456789)
How do I force Tesseract to give me some answer instead of nothing at all?
来源：https://stackoverflow.com/questions/27321553/forcing-tesseract-to-give-some-answer