Illustration of impact of different lines of sight in the same intrinsic spectrum. In the middle bottom panel, we show the intrinsic spectrum escaping the source (black) convolved with the mean IGM transmission at z = 3.0 (yellow). The colour line shows the convolution of the intrinsic spectrum and IGM transmission. The coloured circles show the zELDA reconstruction using the IGM-z model (discussed later). In the other five top panels, individual IGM transmission through different lines of sight are used at z = 3.0.