Patent ID: 6999634

Claim:
A spatio-temporal joint filter for noise reduction comprising: a spatial joint filter including a first filter connected to an input determining a first weighted average of current support region signals of said input using first weighting factors, said current support region signals being included in a current frame, and a second filter connected to said input and an output of said first filter determining a second weighted sum of said input signal and said first weighted average using a second weighting factor that depends on an original signal variance and a noise variance; a temporal joint filter including a third filter connected to an output of said second filter determining a third weighted average of said second weighted sum and previous support region signals of said input signal using third weighting factors, said previous support region signals being included in a previous frame, and a fourth filter connected to an output of said second filter determining a fourth weighted sum of said second weighted sum and said third weighted average using a fourth weighting factor that depends on a spatio-temporal signal variance and said noise variance wherein said fourth weighted sum f o (i,j,t) is determined using the following equation: α ⁡ ( i , j , t ) = σ f 2 ⁡ ( i , j , t ) σ f 2 ⁡ ( i , j , t ) + σ n 2 where f s (i,j,t) is said second weighted sum, μ T (i,j,t) is said third weighted average, σ 2 ST (i,j,t) is said spatio-temporal signal variance, and σ 2 n is a noise variance; σ ST 2 ⁡ ( i , j , t ) = max ⁡ [ σ f 2 ⁡ ( i , j , t ) , σ d 2 ⁡ ( i , j , t ) - σ n 2 2 ] σ d 2 ⁡ ( i , j , t ) = 1 S ⁢ { ∑ ( i , j ) ∈ S ⁢ ( g ⁡ ( i , j , t ) - f o ⁡ ( i , j , t - 1 ) ) 2 } _ where σ 2 f (i,j,t) is a original signal variance, and f o (l,m,t−1) is a previous fourth weighted sum included in said support region of said previous frame; and a frame memory storing said fourth weighted sum and feedbacking said fourth weighted sum to said third filter for a next frame.