Change in filter magnitudes when nebular emission is added to the stellar continuum for low- and high-mass galaxies, shown in the upper panel. Each point marks the median, with error bars indicating the 16th–84th percentile range. Both galaxy populations appear redder, mainly due to strong optical emission lines in the rest frame optical range, with the effect being more pronounced in low-mass systems. The lower panel presents the flux contributions of the stellar continuum, nebular continuum, and nebular emission lines to the F444W magnitude for each galaxy. In galaxies with log M_★/M_⊙ ≲ 7.3, the emission-line contribution is comparable to that of the stellar continuum.