1. An image scanning apparatus comprising: a scanning unit configured to scan a document and generate original image data representing an original image; and a controller configured to: convert the original image data into converted image data representing a first converted image, analyze the original image data and count a number of first characters recognized in the original image represented by the original image data, analyze the converted image data and count a number of second characters recognized in the converted image represented by the first converted image data, compare the number of first characters with the number of second characters and determine which one of the number of first characters and the number of second characters is greater than the other, and output the original image data when the controller determines that the number of first characters is greater than the number of second characters, and output the converted image data when the controller determines that the number of second characters is greater than the number of first characters.