  Document image quality assessment (DIQA) is an important and challenging
problem in real applications. In order to predict the quality scores of
document images, this paper proposes a novel no-reference DIQA method based on
character gradient, where the OCR accuracy is used as a ground-truth quality
metric. Character gradient is computed on character patches detected with the
maximally stable extremal regions (MSER) based method. Character patches are
essentially significant to character recognition and therefore suitable for use
in estimating document image quality. Experiments on a benchmark dataset show
that the proposed method outperforms the state-of-the-art methods in estimating
the quality score of document images.
