Comparison of the cloud sizes of sub-regions in the four molecular clouds as traced by DIB λ6614 and E(BP–RP). The upper panel presents the correlation between size estimates derived from DIB λ6614 and E(BP–RP), with error bars representing measurement uncertainties and colors indicating different molecular clouds. The gray dashed line marks the 1:1 relation. The lower panel shows the distribution of the differences between the two sets of size estimates.