Thank you so much for your sharing. It seems a very complicated cleanup. It will be very useful if you can provide some preprocessing script. And I am wondering there is also some thresholds depending on different images, right?
By the way, I have read some papers about LSTM +Ctc for ocr. The advantages for such techniques is from deep learning. We can get any complicated feature from convolution. So theoretically, it is no need to do such preprocessing. How do you think about this ? On Wed, Apr 3, 2019 at 21:17 Lorenzo Bolzani <[email protected]> wrote: > Hi, I train with real data. I use grayscale images, I think color makes no > difference. > > I do a very good image cleanup: background removal, denoise, > straightening, sharpening, illumination correction, contrast stretching, > etc. before passing the text to tesseract. This part is likely better done > on color images (you can split in RGB/HSV channel depending on what you > need). > > So my final output is already almost "binary" and I do not do any real > binarization/thresholding, I'm not sure if tessaeract does it or not but > the difference would be minimal. > > All the images are rescaled so that the text has always the same height, > about 35/40px, with not border or a small (1/2px) border. Try with an > evaluation set and see what works best for you. > > > Bye > > Lorenzo > > Il giorno mer 3 apr 2019 alle ore 11:08 Du Kotomi <[email protected]> > ha scritto: > >> If we use text2image tool, there is no such problem. >> >> What about training with our real data. I have enough images for >> training. Should I need to do some preprocess like binary or resized dpi >> and then do lstm training? >> >> On Wed, Apr 3, 2019 at 16:36 Shree Devi Kumar <[email protected]> >> wrote: >> >>> Usually for LSTM training we are using synthetic images created by >>> text2image program using training text and fonts using tesstrain.sh or >>> tesstrain.py. Hence there is no question of binarization or dpi as the >>> program creates images as expected by tesseract training process. >>> >>> On Wed, Apr 3, 2019 at 12:31 PM Du Kotomi <[email protected]> wrote: >>> >>>> Anybody here? >>>> >>>> On Wed, Apr 3, 2019 at 09:57 <[email protected]> wrote: >>>> >>>>> Sorry for disturb again. I have sent my issue befire, but no one gives >>>>> the answer. I really need your help. >>>>> >>>>> >>>>> I go through the source code and find tesseract do Otsu Thresholding >>>>> and put the binary pix in the Thresholder object. >>>>> But It seems the Thresholder object haven't been invoked if I use >>>>> lstm engines. >>>>> As well as dpi size,tesseract wiki said it is better for 300 dpi. This >>>>> is a requirement for tesseract 3.0 engine or even before, right? >>>>> If I training lstm tesseract, it doesn't matter whether I do binary or >>>>> resize the dpi of images, right? >>>>> >>>>> >>>>> I will be every appreciated if any response is sent. 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