Rucha > Green? Why? Ger > Indeed, why? (What is the thought that drove you to run this particular imagemagick command?)
Fair questions. I saw both black and white in the text so I picked a background color that does not exist in the text and has high contrast. tesseract did a great job with the green background. I want to process images to extract Palo Alto California tide data, date, and time and then plot the results against xtide predictions. I am close to processing a day's worth of images collected once a minute so I will see how well the green background works. If I have problems, I will definitely try using your (Ger and Rucha's) advice. Thank you Ger and Racha very much for your advice. Best Regards, Michael On Fri, Oct 31, 2025 at 5:52 PM Ger Hobbelt <[email protected]> wrote: > Indeed, why? (What is the thought that drove you to run this particular > imagemagick command?) While it might help visually debugging something > you're trying, the simplest path towards "black text on white background" > is > > 1. converting any image to greyscale. (and see for yourself if that output > is easily legible; if it's not, chances are the machine will have trouble > too, so more preprocessing /before/ the greyscale transform is needed then) > 2. use a 'threshold' (a.k.a. binarization) step to possibly help (though > tesseract can oftentimes do a better job with greyscale instead of hard > black & white as there's more 'detail' in the image pixels then. YMMV). > > You can do this many ways, using imagemagick is one, openCV another. For > one-offs I use Krita / Photoshop filter layers (stacking the filters to get > what I want). > Anything really that gets you something that approaches 'crisp dark/black > text on a clean, white background, text characters about 30px high' (dpi is > irrelevant, though often mentioned elsewhere: tesseract does digital image > pixels, not classical printer mindset dots-per-inch). > > Note that 'simplest path towards' does not mean 'always the best way'. > > Met vriendelijke groeten / Best regards, > > Ger Hobbelt > > -------------------------------------------------- > web: http://www.hobbelt.com/ > http://www.hebbut.net/ > mail: [email protected] > mobile: +31-6-11 120 978 > -------------------------------------------------- > > > On Fri, Oct 31, 2025 at 5:46 AM Rucha Patil <[email protected]> > wrote: > >> Green? Why? I dont know if this might resolve the issue. Lmk the behavior >> I’m curious. But you need an image that has white background and black >> text. You can achieve this easily using cv2 functions. >> >> On Thu, Oct 30, 2025 at 1:26 PM Michael Schuh <[email protected]> wrote: >> >>> I am trying to extract the date and time from >>> >>> [image: time.png] >>> >>> I have successfully use tesseract to extract text from other images. >>> tesseract does not find any text in the above image, >>> >>> michael@argon:~/michael/trunk/src/tides$ tesseract time.png out >>> Estimating resolution as 142 >>> >>> michael@argon:~/michael/trunk/src/tides$ cat out.txt >>> >>> michael@argon:~/michael/trunk/src/tides$ ls -l out.txt >>> -rw-r----- 1 michael michael 0 Oct 30 08:58 out.txt >>> >>> Any help you can give me would be appreciated. I attached the time.png >>> file I used above. >>> >>> Thanks, >>> Michael >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "tesseract-ocr" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion visit >>> https://groups.google.com/d/msgid/tesseract-ocr/77ac0d2b-7796-4f17-8bc6-0e70a9653adan%40googlegroups.com >>> <https://groups.google.com/d/msgid/tesseract-ocr/77ac0d2b-7796-4f17-8bc6-0e70a9653adan%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "tesseract-ocr" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion visit >> https://groups.google.com/d/msgid/tesseract-ocr/CADEFw17btz6nKqyhFKd-GXVCu7qtBQQ6gY5AV0pZJusXa4CpXg%40mail.gmail.com >> <https://groups.google.com/d/msgid/tesseract-ocr/CADEFw17btz6nKqyhFKd-GXVCu7qtBQQ6gY5AV0pZJusXa4CpXg%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "tesseract-ocr" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/tesseract-ocr/CAFP60fpUCz1LFq_aqk0ea6W8GR7a7mrX5%3DPdZhv6%3Dn6t-1YVrg%40mail.gmail.com > <https://groups.google.com/d/msgid/tesseract-ocr/CAFP60fpUCz1LFq_aqk0ea6W8GR7a7mrX5%3DPdZhv6%3Dn6t-1YVrg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "tesseract-ocr" group. 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