1. A computer-implemented method of assessing quality of computer-generated text in a document image, the method comprising: identifying text quality scores associated with a plurality of digital text characters generated from the document image, a text quality score for a target character describing a likelihood of the target character being at a location of the target character within the document image; identifying a plurality of subsets of characters having associated text quality scores that differ from text quality scores associated with neighboring characters in the document image by more than a threshold value; segmenting the document image into a plurality of segments associated with different text quality scores responsive to the identified plurality of subsets of characters; determining a representative text quality score for each segment of the document image; and storing the representative text quality scores in association with the segments.