help me retouch the following English with passive voiceAssuming that $theta_j$ with an initial value of 0 is used to represent whether the $jth$ frame is reserved to reconstruct the background we s

If we assume that $\theta_{j}$, which is initially set to 0, is used to indicate whether the $jth$ frame is reserved for reconstructing the background, then $\theta_{j}$ is set to 1 if the $jth$ frame is selected.