Patent ID: 7561190

Claim:
A method for controlling artifacts in an image due to a presence of flicker in ambient light, comprising: determining a power frequency for the ambient light; determining a magnitude and phase of flicker fluctuation in the image due to the flicker comprising: capturing a first image at an exposure time T 1 =π/ω; capturing a second image at an exposure time T 2 =π/(2ω); determining a function Z(α) defined as Z ⁡ ( α ) = Y ⁡ ( α , π 2 ⁢ ω ) - 1 2 ⁢ Y ⁡ ( α , π ω ) , where Y ⁡ ( α , π 2 ⁢ ω ) ⁢ ⁢ and ⁢ ⁢ Y ⁡ ( C , π ω ) are corresponding pixel values in the second and first images respectively, α is the phase of the flicker fluctuation, and ω=2πf where f is the power frequency of the ambient light; and deriving the magnitude and phase of the flicker fluctuation based on the Z function; and adjusting the image for the flicker fluctuation based on the power frequency, magnitude, and phase.