A couple of weeks ago I had the need to extract text from images. I did a little research and found Tesseract to be a very easy to use tool for this purpose.
The installation is simple. apt-get install tesseract-ocr or brew install tesseract on Linux or Mac respectively.
As an example, here is an image:
The result:
$ tesseract test-text.jpg - -l eng
Helle world /
My exclamation point was wrongly interpreted as a slash, but otherwise it worked quite well!