I found that this PR reduced errors by around 75% in my case: https://github.com/tesseract-ocr/tesseract/pull/3476
On Monday, 28 February 2022 at 02:06:06 UTC+9 zdenop wrote: > my 2 cents: > > First of all create the public testing case/repository focused on this > problem e.g. different font families, font size, shot text (like > 0swZuoU.png), long text, etc. This could be used for finding problems/bugs, > evaluating possible solutions, maybe (re)training. So synthetic data > imitating real-world cases are fine. > I would suggest focusing on the most common fonts as used on different > platforms (e.g. on Windows Arial, Times New Roman, Courier New, Calibri, > Cambria, Consolas, Segoe UI on Linux probably DejaVu, Liberation, Ubuntu, > not sure about Mac&IOS ;-) > I would suggest using column or paragraph style for input image (e.g to > avoid problems with document layout analysis like tables, header, footer..) > > Zdenko > > > ne 27. 2. 2022 o 14:36 Chris McClelland <proph...@gmail.com> napísal(a): > >> So I did a similar analysis to Willus (see link posted by Zdenko), >> downscaling the images to try a range of heights for digits. Unfortunately >> my result is not as nice as Willus's (where he finds that the error rate >> drops to zero for capital-letter heights of 30-33 pixels). In my case I >> have 336 images each containing a column of ~30 #### numbers (dataset T) >> and 336 images each containing a column of ~30 #.# numbers (dataset D). >> >> The error rate for D seems to tend to zero for larger digit-heights (i.e >> more pixels) - the most common errors for smaller sizes seem to be missing >> the decimal point, e.g getting input "1.2" and producing output "12". To >> eliminate those errors, I need digits about 92 pixels high. >> >> The error rate for T is more complex. It has a broad trough in the >> digit-height range 20-48 pixels, with several points (20,32,38) with a >> perfect score, but no obvious range which produces a perfect score. >> >> Perhaps I could train it myself? Is 336*30*4 ~ 40,000 digits of training >> data enough to get meaningful results with OCR? >> >> Chris >> >> On Sunday, 27 February 2022 at 13:23:09 UTC zdenop wrote: >> >>> I do not know. The trick with upscaling is here from version 3.x. The >>> trick with downscaling works from version 4.x >>> Just looking at Willus Dotkom's chart[1] I would guess there is some >>> design decision... But without explanation from original/google >>> programmers, we can just guess or find a bug ;-) >>> >>> [1] >>> https://groups.google.com/group/tesseract-ocr/attach/51b840d4782db/tess4_error_rate.png?part=0.2&view=1 >>> >>> >>> Zdenko >>> >>> >>> ne 27. 2. 2022 o 11:27 Merlijn B.W. Wajer <mer...@archive.org> >>> napísal(a): >>> >>>> Hi, >>>> >>>> On 27/02/2022 08:55, Zdenko Podobny wrote: >>>> > tesseract fix_size.png - >>>> > >>>> > 0326 >>>> > 0939 >>>> > 1552 >>>> > 2206 >>>> > >>>> > >>>> > See doc for explaining: >>>> > >>>> https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#rescaling >>>> >>>> > < >>>> https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#rescaling >>>> > >>>> >>>> Thanks for the suggestion, I'm also running into this problem in some >>>> cases. Is it possible that this is also some kind of segmentation bug? >>>> I >>>> wonder what Tesseract finds here in this clear image that causes it to >>>> produce an extra character. >>>> >>>> Regards, >>>> Merlijn >>>> >>>> -- >>>> 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 tesseract-oc...@googlegroups.com. >>>> >>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/tesseract-ocr/2435ccff-11e1-0848-6d57-600a4262d963%40archive.org >>>> . >>>> >>> -- >> 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 tesseract-oc...@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/tesseract-ocr/33bd80fb-ece5-434c-a44a-84750b416c93n%40googlegroups.com >> >> <https://groups.google.com/d/msgid/tesseract-ocr/33bd80fb-ece5-434c-a44a-84750b416c93n%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 tesseract-ocr+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/tesseract-ocr/efe5e658-e12e-4f31-8795-c32b34264eb5n%40googlegroups.com.
