I wasn't using a formula, just demonstrating that your original text was too small. Here is some advice from the FAQ ( https://code.google.com/p/tesseract-ocr/wiki/FAQ)
Is there a Minimum Text Size? (It won't read screen text!) --- There is a minimum text size for reasonable accuracy. You have to consider resolution as well as point size. Accuracy drops off below 10pt x 300dpi, rapidly below 8pt x 300dpi. A quick check is to count the pixels of the x-height of your characters. (X-height is the height of the lower case x.) At 10pt x 300dpi x-heights are typically about 20 pixels, although this can vary dramatically from font to font. Below an x-height of 10 pixels, you have very little chance of accurate results, and below about 8 pixels, most of the text will be "noise removed". On 13 January 2015 at 21:45, newbie <[email protected]> wrote: > Allistair, > Sorry for coming back to you on this again. When I did the > upscaling of the original picture to 3000px(like you suggested), ocr could > read it. But the resolution on the upscaled picture still seems to be > 96.dpi. How did you arrive at the target 3000px ? Did you have a particular > formula ? > > I came up with the exact pixels to be upscaled to, using paint, so that > the ocr could read it(trail and error). But I am trying to find the common > factor/formula to upscale for any of my images so that the ocr could read > it to produce good accuracy. > > I guess in other words I didnt understand....the below line, in your post > below. Any efforts at ellaborating it, is highly appreciated. > *it should be a ratio of the original size of the cropped image to make it > 300dpi* > > > *Thanks* > On Thursday, January 8, 2015 at 5:08:46 PM UTC-5, Allistair C wrote: >> >> What did the non upscaled version look like - this looks far too blurred >> which is why it's struggling. It might be that your upscaling is too much - >> it should be a ratio of the original size of the cropped image to make it >> 300dpi, rather than always 3000px. >> >> Cheers >> >> On 8 January 2015 at 21:34, newbie <[email protected]> wrote: >> >>> Thanks Allistair. I have it working. The problem is , if I used the same >>> "mantra" of resampling for other images its not working. I have this >>> cropped image(attached, which is also upscaled to 3000 pixels width vice), >>> its coming out VIPZZSO. I need to sharpen this probably. I have to set to >>> very sharp in the preprocessing pgm I am using, but in vain. >>> >>> Any directions. for general preprocessing ? >>> >>> >>> On Thursday, January 8, 2015 at 11:39:55 AM UTC-5, Allistair C wrote: >>>> >>>> OK good. >>>> >>>> I got it working by both resampling (upscaling) the cropped version and >>>> the full image. >>>> >>>> If you are using the "white box" approach so that you have a crop area >>>> (best method) then you just need to upscale that. >>>> >>>> There are many ways to resize an image up - you can find that easily >>>> with Google. I used Open CV for Android and the cvResize function for >>>> example. There are libraries for doing this in Java, .NET, Python etc.. >>>> just look around. >>>> >>>> Cheers >>>> >>>> On 8 January 2015 at 16:24, newbie <[email protected]> wrote: >>>> >>>>> It worked YAY!, you have all my gratitude!. ok now I need to know how >>>>> you did the resampling. I thought you said you took the cropped image and >>>>> resampled. But this seems like the original png file(Arris2500.png) >>>>> resampled. Let me know how you went about resampling and how I can acheive >>>>> it programatically. >>>>> >>>>> Thanks >>>>> >>>>> On Thursday, January 8, 2015 11:06:33 AM UTC-5, Allistair C wrote: >>>>>> >>>>>> Hi, >>>>>> >>>>>> I've not used tess4j but the JavaDocs show that it should be possible >>>>>> to set TessAPI.TessPageSegMode: >>>>>> >>>>>> http://tess4j.sourceforge.net/docs/docs-1.0/net/sourceforge/ >>>>>> tess4j/TessAPI.html >>>>>> >>>>>> http://tess4j.sourceforge.net/docs/docs-1.2/net/sourceforge/ >>>>>> tess4j/TessAPI1.TessPageSegMode.html >>>>>> >>>>>> The 3000 resampled image was: >>>>>> >>>>>> https://dl.dropboxusercontent.com/u/523401/ArrisVIP2500_3000.png >>>>>> >>>>>> Cheers >>>>>> >>>>>> On 8 January 2015 at 15:35, newbie <[email protected]> wrote: >>>>>> >>>>>>> Allistair, >>>>>>> Thanks for taking the time to respond . Do you know how >>>>>>> to use psm 6 in tess4j(its probably an argument to the instantiator, >>>>>>> need >>>>>>> to look up the src code) ? I have not seen any examples of it being >>>>>>> used by >>>>>>> googling.. I tried to resample the cropped image to 3000 px(horizontall >>>>>>> using paint) like you suggested and ran it thro tess4j and it still did >>>>>>> not recognize my model number. Gave me an output of "VIPZSOO". So I >>>>>>> guess >>>>>>> piping it thro psm 6 is the key. Also can u send me the image that was >>>>>>> produced after you resampled it to 3000px, so that I know my resampling >>>>>>> is >>>>>>> right. >>>>>>> >>>>>>> I also like your idea of providing the white box in the camera view >>>>>>> to use it as my input to cropping . Sure can do that. >>>>>>> I think I am glad discussed the feature matching - that seems more >>>>>>> like object recognition than text recognition. So probably is far >>>>>>> fetched. >>>>>>> I had used camFlow(an app) to see if it would recognize my equipment >>>>>>> images >>>>>>> and it always came back with "Black media player". So they probably are >>>>>>> using feature matching of openCV. >>>>>>> >>>>>>> Thanks again and appreciate your taking time to respond. >>>>>>> >>>>>>> >>>>>>> On Wednesday, January 7, 2015 6:12:05 PM UTC-5, Allistair C wrote: >>>>>>>> >>>>>>>> It sort of depends on your hardware and how similar or different >>>>>>>> they are. Reliable feature matching works on distinct features (so >>>>>>>> there >>>>>>>> need to be enough points of interest (edges usually) that cover text, >>>>>>>> buttons, other bits and pieces). If, for example, all your hardware >>>>>>>> was the >>>>>>>> same as the example you originally posted and only the model number was >>>>>>>> changing then this would be an issue most likely as the feature >>>>>>>> matching >>>>>>>> may match several targets. >>>>>>>> >>>>>>>> Also you mention the tech takes a picture on mobile. Does that need >>>>>>>> to be looked up immediately? The issue is that feature matching is CPU >>>>>>>> heavy and can take time on mobile and is a function of the photo >>>>>>>> resolution. Luckily, feature matching appears to work better on lower >>>>>>>> resolution images and most of the time works in black and white. Then >>>>>>>> there >>>>>>>> is the potential number of hardware items you are trying to match. The >>>>>>>> most >>>>>>>> advanced mobile augmented reality products (Metaio, Vuforia) that use >>>>>>>> feature matching only allow up to 100 targets to be "tracked" or >>>>>>>> "looked >>>>>>>> for" at a time - every piece of hardware you are looking for needs to >>>>>>>> be >>>>>>>> compared to the live input camera view (or photo) and this is the part >>>>>>>> that >>>>>>>> hits the CPU hard. If however there was an option to offload the >>>>>>>> image(s) >>>>>>>> to a backend cloud server for feature match or if the tech did not >>>>>>>> need an >>>>>>>> instant or any kind of result in the field, then you are in a better >>>>>>>> situation as you can stand up serious computing power. >>>>>>>> >>>>>>>> It's not easy to recommend one or the other without all the facts - >>>>>>>> as you begin to mention new things like mobile and techs in the field, >>>>>>>> this >>>>>>>> changes things :) For instance I also used mobile - an Android tablet, >>>>>>>> with >>>>>>>> Open CV and Tesseract OCR - the combination worked in the field - the >>>>>>>> tech >>>>>>>> can position the camera face-on to the model number and take a close >>>>>>>> photo. >>>>>>>> You could even provide a mini App for your techs that has a basic >>>>>>>> cropping >>>>>>>> tool. The technique I used was to show the camera view in my app with a >>>>>>>> little white transparent box over the camera view that allowed the >>>>>>>> user to >>>>>>>> position the text to fit that white box. Then, when the photo was >>>>>>>> taken I >>>>>>>> simply cropped that white box coordinate rectangle and I had a perfect >>>>>>>> match. This was easy vs. feature matching :) >>>>>>>> >>>>>>>> On Wednesday, 7 January 2015 23:02:09 UTC, newbie wrote: >>>>>>>>> >>>>>>>>> Sorry for the barrage here. >>>>>>>>> The interesting thing is you mentioned feature matching with >>>>>>>>> openCV(I dont know anything at all about it). But the one thing is I >>>>>>>>> can >>>>>>>>> have a repository of these images with me and I need to match it to >>>>>>>>> one of >>>>>>>>> the user generated image. >>>>>>>>> >>>>>>>>> A little background might help. I can(or come up with) have a >>>>>>>>> repository of all the equipment images with me. A tech might head to >>>>>>>>> the >>>>>>>>> field, take a picture on his mobile device and I need to match >>>>>>>>> it(tech's >>>>>>>>> picture) against my repository and come up with the model number. >>>>>>>>> >>>>>>>>> Is this easier with ocr or feature matching with openCV ? >>>>>>>>> >>>>>>>>> Thanks >>>>>>>>> >>>>>>>>> On Wednesday, January 7, 2015 5:35:47 PM UTC-5, newbie wrote: >>>>>>>>>> >>>>>>>>>> Thanks Allistair , my lucky day as you have responded to both my >>>>>>>>>> queries. Let me try to address your questions below and then go >>>>>>>>>> ahead with >>>>>>>>>> a few of my own :-) >>>>>>>>>> >>>>>>>>>> *I also meant to ask whether your use case allows for cropping. >>>>>>>>>> If you know you will have a certain format of image, cropping an >>>>>>>>>> area and >>>>>>>>>> resampling should be easy.* >>>>>>>>>> Basically the image will be an user generated image, more like >>>>>>>>>> the first png file, but we could ask the user to zoom in to the model >>>>>>>>>> number, if that would help us indentify the model number.we could do >>>>>>>>>> anything with the image(cropping ,resampling etc). But the problem >>>>>>>>>> is the >>>>>>>>>> model number probably will not be located at the same place for all >>>>>>>>>> equipments. >>>>>>>>>> >>>>>>>>>> 2. Preprocessing - as it should be programatically done would I >>>>>>>>>> be using opencv in conjunction with tesseract? I did not see much in >>>>>>>>>> tesseract for image processing(I could be totally off). >>>>>>>>>> 3.*.I also use psm 6 for these types of image with various text >>>>>>>>>> locations.* >>>>>>>>>> what is this ? >>>>>>>>>> >>>>>>>>>> Another thing I probably can come up with is all the model #s or >>>>>>>>>> images of all potential equipments, so I have repository to match >>>>>>>>>> against. >>>>>>>>>> Would that help in any way ? >>>>>>>>>> >>>>>>>>>> Thanks again for taking the time to respond. Appreciate it. >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Wednesday, January 7, 2015 4:44:47 PM UTC-5, Allistair C wrote: >>>>>>>>>>> >>>>>>>>>>> I also meant to ask whether your use case allows for cropping. >>>>>>>>>>> If you know you will have a certain format of image, cropping an >>>>>>>>>>> area and >>>>>>>>>>> resampling should be easy. You could also do some preprocessing >>>>>>>>>>> that looks >>>>>>>>>>> for certain icons in your image to get some context as to where the >>>>>>>>>>> model >>>>>>>>>>> number is likely to be (see feature matching on Open CV). However, >>>>>>>>>>> I would >>>>>>>>>>> need to know more about your use case. >>>>>>>>>>> >>>>>>>>>>> That said, resampling your full image to 3000px wide yielded a >>>>>>>>>>> result with a full model number but the more you can crop the area >>>>>>>>>>> the >>>>>>>>>>> better the result: >>>>>>>>>>> >>>>>>>>>>> AT&T U verse ‘ § >>>>>>>>>>> LINK HD nzc , >>>>>>>>>>> rowzn Q I ‘ .» . ‘ nsuu 4 0|: > I >>>>>>>>>>> / sj J \ >>>>>>>>>>> VIP2500 °%' 7 A R R I s >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On 7 January 2015 at 21:39, Allistair <[email protected]> wrote: >>>>>>>>>>> >>>>>>>>>>>> A common technique is to pre-process your input image. >>>>>>>>>>>> >>>>>>>>>>>> Resizing produced good results.I also use psm 6 for these types >>>>>>>>>>>> of image with various text locations. >>>>>>>>>>>> >>>>>>>>>>>> In this case I first used your cropped image: >>>>>>>>>>>> >>>>>>>>>>>> tesseract ArrisVIP2500_cropped.png out -l eng -psm 6 config >>>>>>>>>>>> >>>>>>>>>>>> and got: >>>>>>>>>>>> >>>>>>>>>>>> AT&T U verse >>>>>>>>>>>> rowsn >>>>>>>>>>>> O F3. >>>>>>>>>>>> vrrzsoo ’e' >>>>>>>>>>>> >>>>>>>>>>>> Then I resampled your image to 2000px wide: >>>>>>>>>>>> >>>>>>>>>>>> tesseract ArrisVIP2500_cropped_2000.png out2000 -l eng -psm 6 >>>>>>>>>>>> config >>>>>>>>>>>> >>>>>>>>>>>> and got: >>>>>>>>>>>> >>>>>>>>>>>> AT&T U verse >>>>>>>>>>>> POWER © " ‘| >>>>>>>>>>>> / ‘j""'j"’.. >>>>>>>>>>>> VIP2500 '%’ >>>>>>>>>>>> >>>>>>>>>>>> Cheers >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> On 7 January 2015 at 19:26, newbie <[email protected]> >>>>>>>>>>>> wrote: >>>>>>>>>>>> >>>>>>>>>>>>> I am using tess4j, a java wrapper around tesseract and Here >>>>>>>>>>>>> are the images and results. The intent is to extract >>>>>>>>>>>>> VIP2500(model number) >>>>>>>>>>>>> from the image. An help is appreciated. >>>>>>>>>>>>> >>>>>>>>>>>>> Attached are the original png file ( >>>>>>>>>>>>> ArrisVIP2500.png),binarized file(ArrisVIP2500_bin.TIF) and then a >>>>>>>>>>>>> zoomed >>>>>>>>>>>>> and cropped file(ArrisVIP2500_cropped.png). >>>>>>>>>>>>> >>>>>>>>>>>>> *ArrisVIP2500.png* >>>>>>>>>>>>> >>>>>>>>>>>>> é ATE-T U-verse >>>>>>>>>>>>> >>>>>>>>>>>>> rowan 0 >>>>>>>>>>>>> / >>>>>>>>>>>>> >>>>>>>>>>>>> *ArrisVIP2500_bin.TIF* >>>>>>>>>>>>> >>>>>>>>>>>>> AT&T U-verse >>>>>>>>>>>>> >>>>>>>>>>>>> rowan <3 3 >>>>>>>>>>>>> / -- >>>>>>>>>>>>> >>>>>>>>>>>>> vxvzsoo ‘Q’ >>>>>>>>>>>>> >>>>>>>>>>>>> *ArrisVIP2500_cropped.png* >>>>>>>>>>>>> >>>>>>>>>>>>> ATE-T U-verse >>>>>>>>>>>>> >>>>>>>>>>>>> rowsn Q >>>>>>>>>>>>> >>>>>>>>>>>>> VIPZSOO ‘e’ This looks the closest to >>>>>>>>>>>>> VIP2500 , I need to get tess4j to reconginze digits, that said, >>>>>>>>>>>>> this might >>>>>>>>>>>>> not be a realistic scenario, as someone/something >>>>>>>>>>>>> >>>>>>>>>>>>> Needs to zoom and >>>>>>>>>>>>> crop the image before hand(preprocessing). >>>>>>>>>>>>> >>>>>>>>>>>>> -- >>>>>>>>>>>>> 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 post to this group, send email to >>>>>>>>>>>>> [email protected]. >>>>>>>>>>>>> Visit this group at http://groups.google.com/group >>>>>>>>>>>>> /tesseract-ocr. >>>>>>>>>>>>> To view this discussion on the web visit >>>>>>>>>>>>> https://groups.google.com/d/msgid/tesseract-ocr/009ffbc7-90c >>>>>>>>>>>>> c-417a-90c8-b4ac9b5bb203%40googlegroups.com >>>>>>>>>>>>> <https://groups.google.com/d/msgid/tesseract-ocr/009ffbc7-90cc-417a-90c8-b4ac9b5bb203%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>>>>>>>>> . >>>>>>>>>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> 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