US2007103484A1PendingUtilityA1
Video to animation conversion with file size constraint
Est. expiryNov 10, 2023(expired)· nominal 20-yr term from priority
H04N 19/124H04N 19/172H04N 19/182H04N 19/40H04N 7/122H04N 19/132H04N 19/186H04N 19/103H04N 19/17H04N 19/142
47
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Claims
Abstract
A method for converting video from a first format into a second format, the method including decoding into a series of frames video that is encoded in a first format, mapping the colors represented in the frames into a palette having fewer colors than the number of colors represented in the frames, removing noise from the frames, selectably removing at least one frame from the sequence, and re-encoding the sequence using the fewer colors into a second video format.
Claims
exact text as granted — not AI-modified1 . A method for converting video from a first format into a second format, the method comprising:
decoding into a series of frames video that is encoded in a first format; mapping the colors represented in said frames into a palette having fewer colors than the number of colors represented in said frames; removing noise from said frames; selectably removing at least one frame from said sequence; and re-encoding said sequence using said fewer colors into a second video format.
2 . A method according to claim 1 wherein said removing noise step comprises:
rasterwise scanning the pixels of palletized images of said frames with a sliding window; determining a pixel value occurring most often within said window; and setting any of said pixels within said window to said most often occurring pixel value.
3 . A method according to claim 2 wherein said setting step comprises setting one of said pixels within a first distance from the leading extent of said window and within a second distance from the trailing extent of said window to said most often occurring pixel value.
4 . A method according to claim 3 wherein said setting step comprises setting where said distances differ.
5 . A method according to claim 2 and further comprising weighting any of said pixel values occurring within said window in accordance with a positionally corresponding predefined weight, wherein said weighting step is performed prior to performing said determining step.
6 . A method according to claim 1 wherein said removing noise step comprises:
deriving a difference frame between two consecutive frames in a sequence of said frames, wherein each pixel position value in said difference frame is set equal to the absolute pixel value difference between its positionally corresponding pixels in both of said consecutive frames; deriving a region of interest mask by multiplying the pixel position values in said difference frame by a weight map and setting any of said pixel position values in said region of interest mask to a predefined value as a function of its weighted value with respect to a predefined threshold; defining a region of interest within the last of said two consecutive frames to include pixels that positionally correspond to pixel positions in said region of interest mask that have a predefined value; and setting any of said pixels in the last of said two consecutive frames that lie inside said region of interest as transparent pixels if said pixels are identical to their positionally corresponding pixels in the first of said two consecutive frames and if said pixels are not part of a larger sequence of contiguous pixels with identical values.
7 . A method according to claim 6 and further comprising excluding any of said pixels in the last of said two consecutive frames that lie outside said region of interest from being used to reconstruct said last frame.
8 . A method according to claim 6 and further comprising:
identifying a segment of pixels in said region of interest, beginning at a pixel location corresponding to a pixel location in said difference frame whose value is equal to 0; determining the number of contiguous pixels in said region of interest extending from said pixel location whose corresponding pixel locations in said difference frame all have a value equal to 0, thereby resulting in a transparency candidate run length; determining the number of contiguous pixels in said region of interest extending from said pixel location having identical color values, thereby resulting in an identical color run length; determining the length of said segment as the longer of said run lengths; and setting the values of the pixels in said segment to a transparent pixel value if said transparency candidate run is longest.
9 . A method according to claim 1 wherein said selectably removing step comprises:
determining the size of a video segment; and should said size exceed a predefined limit:
measuring the amount of information in a frame of said video segment; and
dropping the frame if said amount of information is below a predefined threshold.
10 . A method according to claim 9 wherein said measuring step comprises:
selecting said frame as part of two consecutive frames; and measuring the magnitude of change that occurs between said frame the other selected frame.
11 . A method according to claim 10 wherein said measuring magnitude of change step comprises measuring using the following formula:
SCENE
CHANGE
=
1
N
*
M
*
∑
N
1
∑
M
1
p
1
(
i
,
j
)
-
p
2
(
i
,
j
)
*
w
(
i
,
j
)
where N and M are the ROI dimensions, p k (i,j) is the value of pixel (i,j) in the kth frame and w(i,j) is a weight of a pixel;
12 . A method according to claim 10 wherein said measuring magnitude of change step comprises dividing the sum of absolute difference between pixels in a region of interest of said frame with corresponding pixels in the other selected frame by the number of pixels in said region of interest.
13 . A method according to claim 9 and further comprising performing said steps a plurality of times for a plurality of frames of said video segment until said size does not exceed said predefined limit.
14 . A method according to claim 13 and further comprising recalculating a region of interest and transparency pixels for a subsequent frame of said dropped frame.
15 . A method according to claim 9 and further comprising:
calculating a display duration for said frame to be dropped; retaining said frame in said video sequence if said display duration exceeds a predefined duration threshold.
16 . A system for converting video from a first format into a second format, the system comprising:
means for decoding into a series of frames video that is encoded in a first format; means for mapping the colors represented in said frames into a palette having fewer colors than the number of colors represented in said frames; means for removing noise from said frames; means for selectably removing at least one frame from said sequence; and means for re-encoding said sequence using said fewer colors into a second video format.
17 . A system according to claim 16 wherein said means for removing noise comprises:
means for rasterwise scanning the pixels of palletized images of said frames with a sliding window; means for determining a pixel value occurring most often within said window; and means for setting any of said pixels within said window to said most often occurring pixel value.
18 . A system according to claim 17 wherein said means for setting is operative to set one of said pixels within a first distance from the leading extent of said window and within a second distance from the trailing extent of said window to said most often occurring pixel value.
19 . A system according to claim 18 wherein said means for setting is operative to set where said distances differ.
20 . A system according to claim 17 and further comprising means for weighting any of said pixel values occurring within said window in accordance with a positionally corresponding predefined weight, wherein said means for weighting is operative to weight prior to performing said determining step.
21 . A system according to claim 16 wherein said means for removing noise comprises:
means for deriving a difference frame between two consecutive frames in a sequence of said frames, wherein each pixel position value in said difference frame is set equal to the absolute pixel value difference between its positionally corresponding pixels in both of said consecutive frames; means for deriving a region of interest mask by multiplying the pixel position values in said difference frame by a weight map and setting any of said pixel position values in said region of interest mask to a predefined value as a function of its weighted value with respect to a predefined threshold; means for defining a region of interest within the last of said two consecutive frames to include pixels that positionally correspond to pixel positions in said region of interest mask that have a predefined value; and means for setting any of said pixels in the last of said two consecutive frames that lie inside said region of interest as transparent pixels if said pixels are identical to their positionally corresponding pixels in the first of said two consecutive frames and if said pixels are not part of a larger sequence of contiguous pixels with identical values.
22 . A system according to claim 21 and further comprising means for excluding any of said pixels in the last of said two consecutive frames that lie outside said region of interest from being used to reconstruct said last frame.
23 . A system according to claim 21 and further comprising:
means for identifying a segment of pixels in said region of interest, beginning at a pixel location corresponding to a pixel location in said difference frame whose value is equal to 0; means for determining the number of contiguous pixels in said region of interest extending from said pixel location whose corresponding pixel locations in said difference frame all have a value equal to 0, thereby resulting in a transparency candidate run length; means for determining the number of contiguous pixels in said region of interest extending from said pixel location having identical color values, thereby resulting in an identical color run length; means for determining the length of said segment as the longer of said run lengths; and means for setting the values of the pixels in said segment to a transparent pixel value if said transparency candidate run is longest.
24 . A system according to claim 16 wherein said means for selectably removing comprises:
means for determining the size of a video segment; means for measuring the amount of information in a frame of said video segment where said size exceeds a predefined limit; and means for dropping the frame if said amount of information is below a predefined threshold.
25 . A system according to claim 24 wherein said means for measuring is operative to:
select said frame as part of two consecutive frames; and measure the magnitude of change that occurs between said frame the other selected frame.
26 . A system according to claim 25 wherein said means for measuring magnitude of change is operative to measure using the following formula:
SCENE
CHANGE
=
1
N
*
M
*
∑
N
1
∑
M
1
p
1
(
i
,
j
)
-
p
2
(
i
,
j
)
*
w
(
i
,
j
)
where N and M are the ROI dimensions, p k (i,j) is the value of pixel (i,j) in the kth frame and w(i,j) is a weight of a pixel;
27 . A system according to claim 25 wherein said means for measuring magnitude of change is operative to divide the sum of absolute difference between pixels in a region of interest of said frame with corresponding pixels in the other selected frame by the number of pixels in said region of interest.
28 . A system according to claim 24 wherein said means are operative for a plurality of frames of said video segment until said size does not exceed said predefined limit.
29 . A system according to claim 28 and further comprising means for recalculating a region of interest and transparency pixels for a subsequent frame of said dropped frame.
30 . A system according to claim 24 and further comprising:
means for calculating a display duration for said frame to be dropped; means for retaining said frame in said video sequence if said display duration exceeds a predefined duration threshold.Cited by (0)
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