Hello John, could you provide an example image on which you want to apply Tesseract? I personally have not much experience with images of 7-segment displays, but I know that you're not the first who brought up this question here in the group. I think Tesseract will have some trouble with 7-Segment displays because the characters are indeed "segmented" :) . To isolate an area of brightness, you might try some sort of histogram analysis over one line of your image at a time. Then you could search your line results for similar brightness peaks (value and location of the peak) in subsequent lines.
8flm6 On 2 Jul., 12:58, John Brohan <[email protected]> wrote: > dear 8flm6 > Thanks for your helpful information. > The case I am interested in uses bright 7 segment display of a series of > numbers. The quality of the photographer is unpredictable. I would like to > throw away all the surrounding words and clutter on the screen and send just > these numbers to the OCR system. > I would greatly appreciate any pointers to isolating an area of brightness > in a picture. > Thanks > John > > > > > > > > > > On Fri, Jul 1, 2011 at 3:48 PM, 8flm6 <[email protected]> wrote: > > Take a look at TessBaseAPI::TesseractRect(). This is basically a > > convinience method which wraps up the calls for you. > > In the first step set the image you want to work on. All you need is a > > pointer to your image data ,the dimensions of your image (width, > > height), > > the size of one pixel in bytes (which is 3 for the imag you uploaded) > > and the number of bytes in one line of your image ( = > > size_of_one_pixel * width_of_the_image). > > In the second step you call SetRectangle() giving the coordinates of > > the upper left corner of your ROI and the height and the width > > of the ROI to the method ( you should check prior to that the ROI > > dimensions do not exceed the dimensions of the source image). > > The last step is to call GetUTF8Test() which returns your resultstring > > as char pointer. You might rethink converting your images to grayscale > > as well. > > I got a good result on your image after I grayscaled it in Gimp and > > saved it as BMP: > > >https://docs.google.com/leaf?id=0B2ifXewLRYsdMjAyNTAwZTctZDgyZi00NWM3... > > > On 30 Jun., 18:00, "[email protected]" <[email protected]> wrote: > > > This SetRectangle() method is intriguing. Could you give me an > > > example on how to implement it? 95% of the new meters are on the left > > > half of the picture. > > > > Thanks! > > > > On Jun 29, 1:53 pm, 8flm6 <[email protected]> wrote: > > > > > Hello, > > > > > The Tesseract API provides a SetRectangle() method, to limit the > > > > character recognition to a certain area. > > > > If all of your images look nearly the same (new electric meter on the > > > > lower left side and the old on the right), > > > > you could define a static region of interest which generously covers > > > > the number you'd like to read on every image. > > > > If every image looks different, you will likely need a more elaborate > > > > algorithm which finds the ROIs first, > > > > and then passes the Coordinates to Tesseract. Then in the end you > > > > could apply a regular expression to your reading > > > > results to filter the number you're searching for, something like '/ > > > > [0-9]{2} [0-9]{3} [0-9]{3}/' if the number has always the > > > > format like the one in the picture you uploaded. Hope you'll find a > > > > solution! > > > > > 8flm6 > > > > > On 29 Jun., 13:32, "[email protected]" <[email protected]> wrote: > > > > > > Update: on a batch of 60 meters, I was able to get 46 meters > > > > > recognized. > > > > > > First i ran a batch that runs tesseract on every .tif, and names the > > > > > output <picture name>.txt. > > > > > Then, I simply wrote a batch script to compare a text file of known > > > > > meter numbers against every tesseract output file using findstr. > > > > > The results show up as <picture name>.tif:<picture name>.txt. > > > > > > Is there any way to optimize the pictures to make the text easier to > > > > > read before processing? I tried converting to grayscale last night, > > > > > but it actually hurt the results. The meters that don't come across > > > > > all seem to have minimal glare problems. > > > > > > At any rate, in the trials, I have already saved myself a ton of > > time, > > > > > and for that I am happy. Where's the donate button? > > > > > On Jun 28, 1:30 pm, "[email protected]" <[email protected]> > > wrote: > > > > > > > Scenario: We have 7000+ electric meters being changed out, and > > while > > > > > > changing them out we are taking a picture of the new meter beside > > the > > > > > > old meter to capture the previous reading. We are looking for a > > way > > > > > > to extract the meter number from all 7000 pictures > > programmatically. > > > > > > I have gotten as far as creating a batch script to run tesseract > > for > > > > > > all files in a folder, and create output txt files for all of the > > > > > > images. Within these images I see a bunch of jarbled text, and > > > > > > eventually I find the meter number. My question, can I extract > > just > > > > > > that meter number out of the images programmatically? I have a > > list > > > > > > of all 7000 meter numbers, and considered maybe making a dictionary > > > > > > file of just these. Would that possibly work? Can tesseract be > > set > > > > > > to ignore anything that isn't a dictionary match? > > > > > > > Sample meter file:http://deangrell.com/CIMG0005.tif > > > > > > > The meter number we are trying to read is on the left,76 207 799. > > > > > > Everything pulls across, even the "SANAGAMO" on the bottom of the > > > > > > right meter. This software is truly impressive, I just need to > > find a > > > > > > way to focus it on the meter numbers. > > > > > > > Any help at all would be appreciated! > > > -- > > 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 > > -- > John Brohanhttp://www.woundfollowup.com tel 514 995 3749. > 5 minute moviehttp://tinyurl.com/22kfdv8 -- 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
