add option to output <span class=ocr_word> elements to hocr #314
Conversation
You mean |
|
Thanks, I've edited the comments. I'll look into how I change this in the source code so that the changes pertain in the pull request. |
|
Looks good, thanks. Will there be whitespace between the word spans? To do html2txt, for screenreaders etc.? |
ocropus-hocr
Outdated
| previous_char_x = char_x | ||
| PN("</span>") | ||
| except: | ||
| E("Data for ocr_word elements is not available. Did you select --llocs in ocropus-gpageseg?") |
| PN("</span>") | ||
| except: | ||
| E("Data for ocr_word elements is not available. Did you select --llocs in ocropus-gpageseg?") | ||
| PN(" class='ocr_line' title='%s'>"%info,text,"</span>") |
There was a problem hiding this comment.
Indentation looks off on GitHub.
|
Yes, there is whitespace between the elements. There is not whitespace after the final and the that closes the hocr_line. Apropos formatting, is there a beautifier command that I can run the code through to conform to this project? |
|
I think kraken also has something like this feature. |
👍
PEP8. We discussed beautifying the whole code base but decided against it at the time, because it change every second line and make blameing harder. |
|
Do you take into account the fact that each 'loc' is just one spot that can be in the start / middle / end of glyph? |
|
Amit -- Because of this issue, the assigned break between words is the midpoint of the space between them. (This is noted in the code comments.) This ensures, or tries to, that no part of a cc of a glyph is cut off. It does mean that the word bounding box has some extra space on either side and that each word bbox is adjacent to the next. I feel this is a good compromise, given the data available, since it can be used for retraining, cropping images of words and so forth. I'll provide a visualization later today. |
|
The breaks that occur inside words, such as on the first line, are OCR errors: that is, ocropus-rpred finds a space there, so this code dutifully enters a word. Similarly, the marginal numbers, 655 and 665 are incorrect because of upstream errors. (I find that these marginal numbers sometimes get lost or clipped by gpageseg unless I really jam the column parameters.) I'm processing a few thousand pages in the next couple of days, and I'll pass them through this process to ensure it doesn't throw errors and check the visualizations for good word breaks. |
|
This is the corresponding plaintext output, verifying my analysis of the errors above: |
|
For what it's worth, it's clear we could improve on this code to generate the 'true' bbox of the word by finding the smallest rectangle around all the ccs within the bbox provided by the routine offered in this pull request. If someone could recommend a library, preferably already imported by Ocropus, that does this or that would be best to modify to this purpose, I'd be happy to work on it for a future pull request. |
… as to if they use leading or trailing edge so this is the best we can do.)
This adds a'-w' switch to ocropus-hocr, which will cause it to generate elements containing each word's text and validly nested within the appropriate element. It depends on the .llocs files generated by ocropus-rpred. If these are not available, or the switch is not turned on, it uses the old behaviour.
It should be noted that text output from ocropus-hocr with and without the -w might differ. In particular, initial and final spaces are stripped from lines when the -w switch is on because this tends to generate poor bounding boxes.