Character Recognition
reCAPTCHA: Human-Based Character Recognition via Web Security Measures
FREE-DOWNLOAD [PDF] L von Ahn, B Maurer, C McMillen, D Abraham…
CAPTCHAs (Completely Automated Public Turing test to tell Computers and Humans Apart)
are widespread security measures on the World Wide Web that prevent automated programs
from abusing online services. They do so by asking humans to perform a task that The pages are photographically scanned and the resulting bitmap images are transformed into
text files by optical character recognition (OCR) software. Although there has been work in the
image-processing community on modeling the natural degradation process of scanned