How to automatically detect blurred document images

1. Is there a way to detect if an image is blurry?
2. What is blur detection?
3. How do you calculate blur?

Is there a way to detect if an image is blurry?

The easiest way to detect if an image is blurry or not is to look at the strength of the high frequency content. This can be done with a simple gradient of gaussian filter or a laplacian filter.

What is blur detection?

Blur detection is a pre-processing stage in image restoration. Using different blur detection techniques, the quality of an image can identify if blurry or not. This study aims to provide a comparative performance of the available state-of-the-art blur measure operators or blur detection techniques.

How do you calculate blur?

Image blur is calculated with the basic formula: b = dwScos0 . This equation uses exposure duration directly.