I have the paper titled "CG-DIQA: No-reference Document Image Quality Assessment Based on Character Gradient". It is all about assessing the quality of the document image based on its blurriness. To compute the overall quality score
s of a document image, below are the summary of the steps done:
- An eligible image character patch
cis convolve with a horizontal filter
fxand a vertical filter
fy, which outputs an array of gradient magnitudes. The gradient magnitude of
(i,j)is denoted by
- Get the average gradient magnitude of a specific document image denoted by
Nis the total number of pixels present in all character patches of a specific document.
- Lastly, to the compute the overall quality score s of a document image, standard deviation of the character gradients will be determined.
Now my questions are :
What does it mean when standard deviation is small and big? Does it mean the document image is blurry when the standard deviation is small or vice versa?
How can I normalize the standard deviation outputs , to give it a value of
1when it is not blurry or less than
1when its blurry.