4
edits
OCR Tips: Difference between revisions
m
→Tesseract Tips
m (→Tesseract Tips) |
m (→Tesseract Tips) |
||
| Line 46: | Line 46: | ||
<br>What to look out for: | <br>What to look out for: | ||
Resolution: an x-height below 8-12 pixels will produce very poor OCR return <br> Using a black background for package labels (e.g. lichens, bryophyte) will create a black border that can significantly reduce OCR return<br> Form labels can interfere with OCR output<br> Faded labels or images with poor lighting can be problematic<br> Old font can be problematic. However, it is possible to train Tesseract for new fonts | Resolution: an x-height below 8-12 pixels will produce very poor OCR return <br> Using a black background for package labels (e.g. lichens, bryophyte) will create a black border that can significantly reduce OCR return<br> Form labels can interfere with OCR output<br> Faded labels or images with poor lighting can be problematic<br> Old font can be problematic. However, it is possible to train Tesseract for new fonts | ||
<br>Fixing errors: | <br>Fixing errors: | ||
Tesseract makes characteristic errors. Some of these such as "\/\/" or "\X/" substituted for for "W" can be | Tesseract makes characteristic errors. Some of these such as "\/\/" or "\X/" substituted for for "W" can be | ||
be globally replaced. Others such as "O" substituted for "0", "1" or "!" substituted for "l" or "Z" substituted for "2" or visa versa can be replaced in a context-dependent manner in dates, latitudes and longitudes, etc. For instance, "0ct. !Z, ZOlZ" can be located with a regular expression and changed to "Oct. 12, 2012" so that it can be entered into a database. | be globally replaced as it is highly unlikely that they would occur on their own on a label. Others such as "O" substituted for "0", "1" or "!" substituted for "l" or "Z" substituted for "2" or visa versa can be replaced in a context-dependent manner in dates, latitudes and longitudes, etc. For instance, "0ct. !Z, ZOlZ" can be located with a regular expression and changed to "Oct. 12, 2012" so that it can be entered into a database. | ||
<br>Misc notes: | <br>Misc notes: | ||
Will often recognize vertical text<br> Image input can be tif, jpeg, or gif | Will often recognize vertical text<br> Image input can be tif, jpeg, or gif | ||