METHOD FOR TONE-MAPPING A VIDEO SEQUENCE

1 - 9 . (canceled)

10 . Method for tone-mapping a video sequence in which a local tone-mapping operator is applied on each pixel of each frame of the video sequence to be tone-mapped, characterized in that the spatial neighborhoods defined around the pixels to be tone-mapped and used by said local-tone-mapping operator are determined on a temporal-filtered version of the frame to be tone-mapped.

11 . Method according to claim 10 , wherein the method comprises

obtaining a motion vector for each pixel of the frame to be tone-mapped, and

motion compensating some frames of the video sequence using the estimated motion vectors and temporally filtering the motion-compensated frames to obtain the temporal-filtered version of the frame to be tone-mapped.

12 . Method according to the claim 11 , wherein the method further comprises

detecting non-coherent motion vectors and temporally filtering each pixel of the frame to be tone-mapped using an estimated motion vector only if this motion vector is coherent, a motion vector being detected as being non-coherent when an error (ε n (x,y), ε b,n (x,y), ε f,n (x,y)) between the frame to be tone-mapped and a motion-compensated frame corresponding to this motion vector is greater than a threshold.

13 . Method according to claim 12 , wherein a length N of a temporal filter is obtained, motion-compensated frames are obtained through motion-compensation of the current frame in regard to the frame to be tone-mapped thanks to the estimated motion vectors and the temporal-filtered version of the frame to be tone-mapped) then results from the temporal filtering of said motion-compensated frames using said temporal filter.

14 . Method according to claim 12 , wherein a dyadic wavelet decomposition is applied on the frame to be tone-mapped to build a pyramid where each level corresponds to a low frequency frame belonging to either a forward or backward part, each low frequency subband of each part being computed by using:

a motion prediction step in the course of which a frame H t+1 is obtained from the difference between a reference frame F t+1 and a backward or forward motion-compensated version of a current frame Ft; and

an update step in the course of which a low frequency frame L t belonging to either a forward or backward part is obtained by adding the frame F t with the inverted-motion-compensated version of the frame H t+1 ,

for each pixel of the frame to be tone-mapped, at least one low frequency frame of the backward part is selected and at least one low frequency frame of the forward part are selected and the pixel of the temporal-filtered version of the frame to be tone-mapped is a blending of the two pixels belonging to the two selected low frequency frames.

15 . Method according to the claim 15 , wherein starting from the lowest frequency subband of the backward and the forward parts of the decomposition, all the low frequency subbands of the decomposition are considered and a single low frequency subband is selected for each pixel of the frame to be tone-mapped when the corresponding motion vector is coherent.

16 . Device for tone-mapping a video sequence comprising a local tone-mapping operator, wherein it further comprises means for obtaining a temporal-filtered version of a frame of the video sequence to be tone-mapped and means for determining the spatial neighborhoods defined around the pixels to be tone-mapped and used by said local-tone-mapping operator.

17 . Device according to the claim 16 , wherein it further comprises means configured to implement one of the method according to claim 10 .