Never used an OCR library before so gave it a challenge with the latest xkcd cartoon.

curl https://ocr.a9t9.com/api/Parse/Image --data "apikey=helloworld&url=http://imgs.xkcd.com/comics/bells_theorem.png" { "ParsedResults": [ { "FileParseExitCode": 1, "ParsedText": "T-as IS CALLED I THEOREM. IT LAS FIRST\u2014 t: 1 wostcop n, FASTER- FIRM-LIGHT com)MCBT10N IS E6SlBLE! EL's rta\u201eNDERSTRtDlNGS ELLS THEX\u00dcI I-IPPPEN VIOLATE LOCALITY", "ErrorMessage": "", "ErrorDetails": "" } ], "OCRExitCode": 1, "IsErroredOnProcessing": false, "ErrorMessage": null, "ErrorDetails": null }