Method for detecting and selecting good quality image frames from video
First Claim
Patent Images
1. A method of determining a quality value of a frame, the method comprising the steps of:
- dividing the frame into a plurality of tiles;
determining a motion magnitude for each said tile based upon (i) pixel values of the tile and (ii) pixel values of a corresponding tile of a preceding frame;
determining a focus magnitude attribute for each tile of the plurality of tiles having a motion magnitude attribute below a predetermined threshold, the focus magnitude attribute being based on pixel values of the tile; and
establishing the quality value of the frame by;
(1) testing the motion and focus magnitude attributes of the frame against predetermined criteria; and
(2) defining the quality value of the frame depending upon results of said testing.
1 Assignment
0 Petitions
Accused Products
Abstract
A method of determining a quality value for an image frame is disclosed. The method comprises dividing (in a step 202) the frame into a plurality of tiles (906) and determining attributes (in a step 206) of each said tile based upon pixel values of the tile, and pixel values of a corresponding tile of a preceding frame. The method then establishes (in steps 210, 212) the quality value of the frame by testing the tile attributes of the frame against pre-determined criteria. The method then defines (in a step 220) the quality value of the frame depending upon results of the testing.
-
Citations
36 Claims
-
1. A method of determining a quality value of a frame, the method comprising the steps of:
-
dividing the frame into a plurality of tiles; determining a motion magnitude for each said tile based upon (i) pixel values of the tile and (ii) pixel values of a corresponding tile of a preceding frame; determining a focus magnitude attribute for each tile of the plurality of tiles having a motion magnitude attribute below a predetermined threshold, the focus magnitude attribute being based on pixel values of the tile; and establishing the quality value of the frame by;
(1) testing the motion and focus magnitude attributes of the frame against predetermined criteria; and
(2) defining the quality value of the frame depending upon results of said testing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. An apparatus for determining a quality value of a frame, the apparatus comprising:
-
means for dividing the frame into a plurality of tiles; means for determining a motion magnitude attribute for each said tile based upon (i) pixel values of the tile and (ii) pixel values of a corresponding tile of a preceding frame; means for determining a focus magnitude attribute for each tile of the plurality of tiles having a motion magnitude attribute below a predetermined threshold, the focus magnitude attribute being based on pixel values of the tile; and means for establishing the quality value of the frame comprising;
(1) means for testing the motion and focus magnitude attributes of the frame against predetermined criteria; and
(2) means for defining the quality value of the frame depending upon results of the testing.
-
-
14. A computer readable storage medium having a computer program recorded therein for directing a processor to execute a method of determining a quality value of a frame, said computer program comprising:
-
code for dividing the frame into a plurality of tiles; code for determining a motion magnitude attribute for each said tile based upon (i) pixel values of the tile and (ii) pixel values of a corresponding tile of a preceding frame; code for determining a focus magnitude attribute for each tile of the plurality of tiles having a motion magnitude attribute below a predetermined threshold, the focus magnitude attribute being based on pixel values of the tile; and code for establishing the quality value of the frame comprising;
(1) code for testing the motion and focus attributes of the frame against predetermined criteria; and
(2) code for defining the quality value of the frame depending upon results of the testing.
-
-
15. A video frame selected from a sequence of video frames dependent upon a quality value of the frame, the frame being selected by a method of determining a quality value of a video frame, said method being applied to each frame in the sequence, said method comprising, in regard to a particular frame in the sequence, the steps of:
-
dividing the frame into a plurality of tiles; determining a motion magnitude attribute for each said tile based upon (i) pixel values of the tile and (ii) pixel values of a corresponding tile of a preceding frame; determining a focus magnitude attribute for each tile of the plurality of tiles having a motion magnitude attribute below a predetermined threshold, the focus magnitude attribute being based on pixel values of the tile; and establishing the quality value of the frame by;
(1) testing the motion and focus attributes of the frame against predetermined criteria; and
(2) defining the quality value of the frame depending upon results of said testing. - View Dependent Claims (34)
-
-
16. A method of estimating quality of an image in a video, the video comprising a plurality of images, each image comprising a plurality of pixels, said method comprising the steps of:
-
arranging, for a current image of the video, pixels of the current image into a plurality of tiles, each said tile containing a plurality of pixels; determining the number of the tiles of the current image having defined characteristics; and estimating quality of the current image based on the number of the tiles having the characteristics as a proportion of the number of tiles in the current image, wherein the characteristics are (a) a motion characteristic, determined for each tile, based upon (i) pixel values of the tile and (ii) pixel values of a corresponding tile, of a preceding image, and (b) a focus characteristic, determined for each tile having a motion characteristic below a predetermined threshold, the focus characteristic being based on pixel values of the tile, and wherein the motion characteristic establishes a motion magnitude in the tile, and the focus characteristic establishes a focus magnitude in the tile. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
-
-
17. A method of selecting an image from a video comprising a plurality of images, each image comprising a plurality of pixels, wherein said method comprises the steps of:
-
(a) performing, for each image of the plurality of images, the steps of;
(1) arranging pixels of the image into a plurality of tiles, each said tile containing a plurality of pixels;
(2) determining the number of the tiles of the image having defined characteristics; and
(3) estimating quality of the image based on the number of the tiles having the characteristics as a proportion of the number of tiles in the image; and(b) selecting an image from the video in accordance with the estimated quality, wherein the characteristics are (a) a motion characteristic, determined for each tile, based upon (i) pixel values of the tile and (ii) pixel values of a corresponding tile of a preceding image, and (b) a focus characteristic, determined for each tile having a motion characteristic below a predetermined threshold, the focus characteristic being based on pixel values of the tile, and wherein the motion characteristic establishes a motion magnitude in the tile, and the focus characteristic establishes a focus magnitude in the tile.
-
-
35. A method of determining a quality value of a frame, the method comprising the steps of:
-
dividing the frame into a plurality of tiles; determining attributes of each said tile based upon (i) pixel values of the tile and (ii) pixel values of a corresponding tile of a preceding frame, wherein the attributes comprise a motion definition state and a motion magnitude, the motion definition state being determined by classifying the tile as having a motion defined state if one of (i) an intensity range of pixels in the tile or in the corresponding tile of the preceding frame exceeds a pre-determined luminance threshold and (ii) a difference between mid-range pixel values for the tile and the corresponding tile of the preceding frame exceeds a pre-determined mid-range difference threshold, and determining the motion magnitude, if the tile has a motion defined state, based upon a difference in pixel value distributions between a pixel value histogram of the tile and a pixel value histogram of the corresponding tile in the previous frame; and establishing the quality value of the frame by;
(1) testing the tile attributes of the frame against pre-determined criteria; and
(2) defining the quality value of the frame depending upon results of said testing, wherein;the frame is one of a sequence of video frames; the method is applied to each frame in the sequence; and the best frame in the sequence is identified as that frame having the best quality value.
-
-
36. A method of determining a quality value of a frame, the method comprising the steps of:
-
dividing the frame into a plurality of tiles; determining attributes of each said tile based upon pixel values of the tile, wherein the attributes comprise a focus definition state and a focus magnitude, the focus definition state being determined by classifying the tile as having a focus undefined state if (i) an intensity range of pixels in the tile is less than a predetermined threshold, or (ii) a number of defined difference quotients in the tile is less than a threshold, and determining the focus magnitude based on the largest difference quotient values of pixel luminance of the tile; and establishing the quality value of the frame by;
(1) testing the tile attributes of the frame against pre-determined criteria; and
(2) defining the quality value of the frame depending upon results of said testing, wherein;the frame is one of a sequence of video frames; the method is applied to each frame in the sequence; and the best frame in the sequence is identified as that frame having the best quality value.
-
Specification