Thanks for correcting me - really I did not remember that information.
--
Zdenko
On 05.12.2012 08:06, Speedy wrote:
Just check out Ray's October 2007 paper "An Overview of the Tesseract OCR
Engine" where it says:
The first step is
a connected component analysis in which outlines of
the components are stored. This was a computationally
expensive design decision at the time, but had a
significant advantage: by inspection of the nesting of
outlines, and the number of child and grandchild
outlines, it is simple to detect inverse text and
recognize it as easily as black-on-white text. Tesseract
was probably the first OCR engine able to handle
white-on-black text so trivially.
And in fact, in our own application after image preprocessing we pass the
binarized image as a white-on-black image to tesseract and never had
problems with that. Of course, our training images are also white-on-black,
so this might also affect our findings.
Marcus
On Tuesday, December 4, 2012 2:58:26 PM UTC+1, zdenop wrote:
Where did you find "advertised features of tesseract is that it works
equally well for black-on-white and white-on-black text"? I never heard
about it.
See forum for other experience:
https://groups.google.com/d/topic/tesseract-ocr/XoX6t5Ih1IM/discussion
--
Zdenko
On Tue, Dec 4, 2012 at 2:42 PM, Speedy <marcus....@efkon.com <javascript:>
wrote:
Why is a black background a problem? One of the advertised features of
tesseract is that it works equally well for black-on-white and
white-on-black text.
Marcus
On Tuesday, December 4, 2012 11:11:36 AM UTC+1, zdenop wrote:
Search forum. I remember discussion about **similar topic.
AFAIR: tesseract has problem with letter(symbol) that consists of
several not connected parts (e.g. dots, lines) - solution should be to
preprocess image (blur).
Generally: black background is problem. Quality of image is too low
(JPEG, quality: 75), there is no information about DPI... Anyway this "LED"
font is not standard font, so maybe training will be need.
--
Zdenko
On Tue, Dec 4, 2012 at 12:43 AM, mike oldfield <czandr...@gmail.com>wrote:
<https://lh5.googleusercontent.com/-Ly6oR_Rmkag/UL04-iH5XaI/AAAAAAAAAAU/J-T592D8834/s1600/1.jpg>
Hello
I`d like to recognize LED-like numbers/digits.
I attached image (jpg, 680x320, brightness 65%, contrast 100%).
Is there any libraries or presets to decode these digits? For example
googledocuments conversion and free-ocr.com doesn`t work.
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