Patent Document ID: 9686449
Application ID: 15075079
Patent Status: 1

Claim One:
1. A method for determining blur in a video having at least one image, due to high quantization adopted during encoding of the image, the method comprising the steps of: preprocessing the image for filtering out the noise; extracting an edge image by extracting gradients of the preprocessed image; determining a grid periodicity and an offset in horizontal and vertical direction for the edge image; determining a blockiness metric based on the validation of a grid in the previous step; determining a ringing metric, based on, determining a gradient sign change for each pixel of the edge image; determining an edge direction change image by utilizing the gradient sign change for each pixel of the edge image; determining maximum absolute gradient magnitude for each row of the edge image based on the pixel values of each pixel in each row of the edge image; determining a Principal Edge (PE) image by determining a first set of absolute gradients for each row that are greater than a first predefined percentage of the maximum absolute gradient magnitude for that row; determining a Highly Significant Edge (HSE) Image by determining a second set of absolute gradients for each row that are greater than a threshold, the threshold being equal to the greater of either a programmable constant or a multiple of the first predefined percentage of the maximum absolute gradient magnitude; detecting ripples around a set of edge pixels of the determined Highly Significant Edge (HSE) image for determining a ringing pixel count and a ringing strength aggregate by, detecting change of gradient direction in a predefined neighbourhood of the each highly significant edge pixel by utilizing the edge direction change image, the change of gradient direction is detected in a horizontal direction and a vertical direction; detecting one or more right overshoots, corresponding one or more right troughs, and corresponding one or more right crests; detecting one or more left overshoots, corresponding one or more left troughs, and corresponding one or more left crests; determining the aggregate of ringing pixel count by incrementing the current value of the ringing pixel count when one of a first set of conditions or a second set of conditions are true, the first set of conditions and a second set of conditions are based on at least a right crest, a right trough, a left crest and a left trough; and determining the ringing strength aggregate by adding difference between one and a ratio of the difference between corresponding right trough and left trough and the difference between corresponding right crest and left crest; determining a principal edge thickness aggregate based on thickness of each edge present in PE image; determining a count of principal edge segments by determining total number of edge segments present in the Principal Edge (PE) image image; computing the ringing metric, based on the ringing pixel count, the ringing strength aggregate, the principal edge thickness aggregate and the count of principal edge segments; generating a gradient histogram by using the grid periodicity and the offset of the gradients that are off the grid; computing a mean and kurtosis of the gradient histogram; determining a perceptual blurriness metric based on the computed mean and kurtosis; and determining a composite blurring metric based on, the determined perceptual blurriness metric, the determined blockiness metric when the magnitude of the blockiness metric is greater than the predetermined threshold, or the determined perceptual blurriness metric and the determined ringing metric when the magnitude of the blockiness metric is less than the predetermined threshold.