I need to extract words from small images like this:
I am using tesseract from the command line with spanish language option, like this:
tessera
Tesseract seems to really struggle when scanning low resolution characters.
Try to scan this image. I enhanced its resolution by 400 percent (I think 200 percent is possible for scanning, but lets try 400%), did a great amount of blurring and did threshold of ~140 value. Try scanning this one, the results should be much better and I hope this satisfy you. If you need to do that programmatically, write in comments what is unclear for you, I will provide you some additional information.