Document Quality Estimation Using Spatial Frequency Response

The current Document Image Quality Assessment (DIQA) algorithms directly relate the Optical Character Recognition (OCR) accuracies with the quality of the document to build supervised learning frameworks. This direct correlation has two major limitations: (a) OCR may be affected by factors independent of the quality of the capture and (b) it cannot account for blur variations within an image. An alternate possibility is to quantify the quality of capture using human judgement, however, it is subjective and prone to error. In this work, we build upon the idea of Spatial Frequency Response (SFR) to reliably quantify the quality of a document image. We present through quantitative and qualitative experiments that the proposed metric leads to significant improvement in document quality prediction in contrast to using OCR as ground truth.