The depth-resolved complex reflectivity of a scattering sample is reconstructed by performing Fourier transform of the spectral interference fringe signals in SDOCT. The complex-valued OCT signals of the $n$’th repeated B-frame is denoted as $A\u02dc(z,x,n)$. A map of the amplitude signals $A(z,x,n)$ is used to generate the structural image. The differences of the amplitude $A(z,x,n)$^{18} and complex-valued $A\u02dc(z,x,n)$^{17} OCT signals between adjacent B-frames are computed for AD- and CD-Angio-OCT, respectively, as follows: Display Formula
$AngioOCTAD=aAD(z,x,n)=A(z,x,n+1)\u2212A(z,x,n),$(1)
Display Formula$AngioOCTCD=aCD(z,x,n)=|A\u02dc(z,x,n+1)\u2212A\u02dc(z,x,n)|,$(2)
where $aAD$ and $aCD$ represent the amplitude of AD-Angio-OCT and CD-Angio-OCT signals, respectively. Typically, the absolute value of $aAD$ is used in the final angiograms in AD-Angio-OCT. The adjacent B-frames are acquired at the same cross section with a certain time interval ($t$). Then thresholds are used to identify the dynamic areas. Due to the bulk motion, prior to the subtraction operation in Eq. (2), the global phase fluctuations are determined and compensated by a histogram-based phase selecting process.^{9}^{,}^{16}^{,}^{25}^{–}^{27}