On Wed, Dec 5, 2012 at 11:02 AM, mike oldfield <[email protected]>wrote:
> Tesseract-ocr has still problem with decoding of LED-like digits. > I made something like this in my squeeze comand line: > convert 1.jpg 1.tif && tesseract 1.tif 1.txt nobatch digits > ...but effects are very poor and far very far from the truth ;) > IMO converting from one format to other one do no help. config "digits" is a good option - it can help in case of "S" vs "5" , "B" vs "8" "l" "1" problem... I would suggest to use pagesegmode 7 or 8. > the same siyuation is when I make negativ (black digits on white > background): > convert 1.jpg -negate 1-negativ.jpg && tesseract 1.tif 1.txt nobatch digits > > I wrote article: > http://www.seeingwithsound.com/ocr.htm > djpeg -grayscale -dither none -outfile 1.pnm 1.jpg && gocr -i 1.pnm -o > 1.txt > and results are better (no "." but digits are properly decoded , but 1 > instead of 7 and S instead of 5) > > I tried to use http://www.onlineocr.net/ and results are impressive !!! I > minimize picture to 176x144 , YUYV palette instead of MJPEG, brightes: > 100%, 96x96dpi number of frames on 1 picture 50, results has "." in the > right place, but problem with "7"->"1" and "5"->"S" > > I`ve question, which algoritm is uded by onlineocr.net?For example > free-ocr.com , newocr.com has very bad results (same as tessearct fresh > installed in debian) > > I think it is not only about OCR algorithm, but also about improving (preprocessing) input image and OCR training. BTW: there is dedicated 7 segment OCR[1]. [1] http://www.unix-ag.uni-kl.de/~auerswal/ssocr/ > I attache some pictures made by my logitech c120 (and negative copy). > > tesseract 1.jpg 1 quiet && cat 1.txt 35.3 ;-) > > > > > > W dniu środa, 5 grudnia 2012 08:06:20 UTC+1 użytkownik Speedy napisał: > >> 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<https://groups.google.com/d/topic/tesseract-ocr/XoX6t5Ih1IM/discussion> >>> >>> -- >>> Zdenko >>> >>> On Tue, Dec 4, 2012 at 2:42 PM, Speedy <[email protected]> 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 **simi**lar 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 <[email protected]>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. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "tesseract-ocr" group. >>>>>> To post to this group, send email to [email protected] >>>>>> >>>>>> To unsubscribe from this group, send email to >>>>>> tesseract-oc...@**googlegroups.**com >>>>>> >>>>>> For more options, visit this group at >>>>>> http://groups.google.com/**group**/tesseract-ocr?hl=en<http://groups.google.com/group/tesseract-ocr?hl=en> >>>>>> >>>>> >>>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "tesseract-ocr" group. >>>> To post to this group, send email to [email protected] >>>> To unsubscribe from this group, send email to >>>> tesseract-oc...@googlegroups.**com >>>> For more options, visit this group at >>>> http://groups.google.com/**group/tesseract-ocr?hl=en<http://groups.google.com/group/tesseract-ocr?hl=en> >>>> >>> >>> >>> -- > You received this message because you are subscribed to the Google > Groups "tesseract-ocr" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/tesseract-ocr?hl=en > -- You received this message because you are subscribed to the Google Groups "tesseract-ocr" group. 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